check engine light FORD MONDEO 1993 Service Service Manual

into the inlet ports, just above the inlet valves,
by four fuel injectors. The system also
includes features such as the flushing of fresh
(ie, cold) fuel around each injector on start-up,
thus improving hot starts.
The amount of fuel supplied by the injectors
is precisely controlled by an Electronic
Control Unit (ECU). The ECU uses the signals
derived from the engine speed/crankshaft
position sensor and the camshaft position
sensor, to trigger each injector separately in
cylinder firing order (sequential injection), with
benefits in terms of better fuel economy and
lower exhaust emissions.
Air induction system
The air system consists of an air filter
housing, an air mass meter, an intake
resonator and plenum chamber, and a throttle
housing. The air mass meter is an information-
gathering device for the ECU; it uses a “hot-
wire” system to send the ECU a constantly-
varying (analogue) voltage signal
corresponding to the volume of air passing
into the engine. Another sensor in the air mass
meter measures intake air temperature. The
ECU uses these signals to calculate the mass
of air entering the engine.
The throttle valve inside the throttle housing
is controlled by the driver, through the
accelerator pedal. As the valve opens, the
amount of air that can pass through the
system increases. The throttle potentiometer
opens further, the air mass meter’s signal
alters, and the ECU opens each injector for a
longer duration, to increase the amount of fuel
delivered to the inlet ports.
Electronic control system
The ECU controls the fuel injection system,
as well as the other sub-systems which make
up the entire engine management system. It
receives signals from a number of information
sensors, which monitor such variables as
intake air mass and temperature, coolant
temperature, engine speed and position,
acceleration/deceleration, and exhaust gas
oxygen content. These signals help the ECU
determine the injection duration necessary for
the optimum air/fuel ratio. These sensors and
associated ECU-controlled relays are located
throughout the engine compartment. For
further information regarding the ECU and its
control of the engine management system,
see Chapter 6.
Idle speed and mixture
adjustment - general
Both the idle speed and mixture are under
the control of the ECU, and cannot be
adjusted. Not only can they not be adjusted,
they cannot even be checked, except with the
use of special diagnostic equipment (see
Chapter 6) - this makes it a task for a Ford
dealer service department. Do notattempt to
“adjust” these settings in any way without
such equipment.
If the idle speed and mixture are thought tobe incorrect, take the vehicle to a Ford dealer
for the complete system to be tested.
On models equipped with a heated
windscreen, an idle-increase solenoid valve is
fitted, which raises the idle speed to
compensate for the increased load on the
engine when the heated windscreen is
switched on. When the valve is open, air from
the plenum chamber bypasses the throttle
housing and idle speed control valve, passing
directly into the inlet manifold through the
union on its left-hand end. The system is
active only for the four minutes that the
heated windscreen circuit is live, and is
supplementary to the main (ECU-controlled)
idle speed regulation.
Warning: Petrol is extremely
flammable, so extra precautions
must be taken when working on
any part of the fuel system. Do
not smoke, or allow open flames or bare
light bulbs, near the work area. Don’t work
in a garage if a natural gas-type appliance
with a pilot light is present. While
performing any work on the fuel system,
wear safety glasses, and have a dry
chemical (Class B) fire extinguisher on
hand. If you spill any fuel on your skin,
rinse it off immediately with soap and
water.
Note: This is an initial check of the fuel delivery
and air induction sub-systems of the engine
management system, to be carried out in
conjunction with the operational check of the
fuel pump (see Section 8), and as part of the
preliminary checks of the complete engine
management system (see Section 3 of
Chapter 6).
1Check the earth wire connections for
tightness. Check all wiring and electrical
connectors that are related to the system.
Loose electrical connectors and poor earths
can cause many problems that resemble
more serious malfunctions.
2Check to see that the battery is fully-
charged. The ECU and sensors depend on an
accurate supply voltage to properly meter the
fuel.
3Check the air filter element - a dirty or
partially-blocked filter will severely impede
performance and economy (see Chapter 1).
4If a blown fuse is found, renew it and see if
it blows again. If it does, search for a short-
circuited wire in the harness related to the
system (see Chapter 6).
5Check the air intake duct from the intake to
the inlet manifold for leaks, which will result in
an excessively-lean mixture. Also check the
condition of the vacuum hoses connected to
the inlet manifold.
6Remove the plenum chamber from the
throttle housing. Check the throttle valve for
dirt, carbon or other residue build-up. If it’sdirty, seek the advice of a Ford dealer - since
the electronic control system is designed to
compensate for factors such as the build-up
of dirt in the throttle housing, it may well be
best to leave it dirty, unless the deposits are
extensive. Note: A warning label on the
housing states specifically that the housing
bore and the throttle valve have a special
coating, and must not be cleaned using
carburettor cleaner, as this may damage it.
7With the engine running, place a
screwdriver or a stethoscope against each
injector, one at a time. Listen through the
screwdriver handle or stethoscope for a
clicking sound, indicating operation.
8If an injector isn’t operating (or sounds
different from the others), turn off the engine,
and unplug the electrical connector from the
injector. Check the resistance across the
terminals of the injector, and compare your
reading with the resistance value listed in this
Chapter’s Specifications. If the resistance
isn’t as specified, renew the injector.
9A rough idle, diminished performance
and/or increased fuel consumption could also
be caused by clogged or fouled fuel injectors.
Fuel additives that can sometimes clean
fouled injectors are available at car accessory
shops.
10The remainder of the system checks
should be left to a dealer service department
or other qualified repair specialist, as there is
a chance that the ECU may be damaged if
tests are not performed properly.
Warning: The fuel system
pressure must be released before
any part of the system is
disturbed - see Section 2. Petrol
is extremely flammable, so take extra
precautions when you work on any part of
the fuel system. Don’t smoke, or allow
open flames or bare light bulbs, near the
work area. Don’t work in a garage where a
natural gas-type appliance (such as a
water heater or clothes dryer) with a pilot
light is present. If you spill any fuel on your
skin, rinse it off immediately with soap and
water. When you perform any kind of work
on the fuel system, wear safety glasses,
and have a Class B type fire extinguisher
on hand.
Throttle housing
Check
1Remove the plenum chamber (see Sec-
tion 4), and verify that the throttle linkage
operates smoothly.
2If the housing bore and valve are dirty
enough for you to think that this might be the
cause of a fault, seek the advice of a Ford
dealer. Do notclean the housing (see the
notes in the checking procedure given in
Section 15).
16 Fuel system components-
check and renewal
15 Fuel injection system/engine
management system - check
Fuel and exhaust systems 4•9
4
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rings, and intend to re-use the same injectors,
remove the old nose seal and O-rings, and
discard them.
22Further testing of the injector(s) is beyond
the scope of the home mechanic. If you are in
doubt as to the status of any injector(s), it can
be tested at a dealer service department.
23Refitting is the reverse of the removal
procedure, noting the following points:
(a) Lubricate each nose seal and O-ring with
clean engine oil on installation.
(b) Locate each injector carefully in the fuel
rail recess, ensuring that the locating tab
on the injector head fits into the slot
provided in the rail. Tighten the bolts to
the specified torque.
(c) Fit a new seal to each fuel rail nose, and
ensure the seals are not displaced as the
rail is refitted. Ensure that the fuel rail is
settled fully in the manifold before
tightening the three bolts evenly and to
the torque wrench setting specified.
(d) Fasten the fuel feed and return quick-
release couplings as described in Sec-
tion 3.
(e) Ensure that the breather hose, vacuum
hose and wiring are routed correctly, and
secured on reconnection by any clips or
ties provided.
(f) On completion, switch the ignition on and
off five times, to activate the fuel pump and
pressurise the system, without cranking
the engine. Check for signs of fuel leaks
around all disturbed unions and joints
before attempting to start the engine.
Fuel pressure regulator
Check
24Refer to the fuel pump/fuel pressure
check procedure (see Section 8).
Renewal
25Relieve the residual pressure in the fuel
system (see Section 2), and equalise tank
pressure by removing the fuel filler cap.
Warning: This procedure will
merely relieve the increased
pressure necessary for the engine
to run - remember that fuel will
still be present in the system components,
and take precautions accordingly before
disconnecting any of them.26Disconnect the battery negative (earth)
lead - see Chapter 5, Section 1.
27Remove the plenum chamber (see
Section 4).
28Disconnect the vacuum hose from the
regulator.
29Unscrew the two regulator retaining bolts,
place a wad of clean rag to soak up any spilt
fuel, and withdraw the regulator (see
illustration).
30Refitting is the reverse of the removal
procedure, noting the following points:
(a) Renew the regulator sealing O-ring
whenever the regulator is disturbed.
Lubricate the new O-ring with clean
engine oil on installation.
(b) Locate the regulator carefully in the fuel
rail recess, and tighten the bolts to the
specified torque wrench setting.
(c) On completion, switch the ignition on and
off five times, to activate the fuel pump and
pressurise the system, without cranking
the engine. Check for signs of fuel leaks
around all disturbed unions and joints
before attempting to start the engine.
Idle speed control valve
Check
31Disconnect the battery negative (earth)
lead - see Chapter 5, Section 1.
32Raise the front of the vehicle, and support
it securely on axle stands.
Warning: Do not place any part of
your body under a vehicle when
it’s supported only by a jack!
33Unplug the valve’s electrical connector
(see illustration).
34Connect a 12-volt battery across the
valve’s terminals - positive (+) to terminal 37
(the green/yellow wire) and negative (-) to
terminal 21 (the black/yellow).
Caution: It is essential that the
correct polarity is observed, or
the diode incorporated in the
valve may be damaged.
35A distinct click should be heard each time
contact is made and broken. If not, measure
the resistance between the terminals. If the
resistance is as specified, the valve is okay
(but there may be a problem with the wiring or
the ECU). If the resistance is not as specified,
renew the valve (see below).36Plug in the valve’s electrical connector.
Renewal
37Disconnect the battery negative (earth)
lead - see Chapter 5, Section 1.
38Raise the front of the vehicle, and support
it securely on axle stands.
Warning: Do not place any part of
your body under a vehicle when
it’s supported only by a jack!
39Unplug the valve’s electrical connector.
40Unscrew the two retaining bolts, and
withdraw the valve from the inlet manifold
(see illustration).
41Since the valve’s individual components
are not available separately, and the complete
assembly must be renewed if it is thought to
be faulty, there is nothing to be lost by
attempting to flush out the passages, using
carburettor cleaner or similar solvent. This
won’t take much time or effort, and may well
cure the fault.
42Refitting is the reverse of the removal
procedure, noting the following points:
(a) Clean the mating surfaces carefully, and
always fit a new gasket whenever the
valve is disturbed.
(b) Tighten the bolts evenly and to the
specified torque wrench setting.
(c) Once the wiring and battery are
reconnected, start the engine and allow it
to idle. When it has reached normal
operating temperature, check that the idle
speed is stable, and that no induction (air)
leaks are evident. Switch on all electrical
loads (headlights, heated rear window,
etc), and check that the idle speed is still
correct.
Fuel and exhaust systems 4•11
4
16.43 Location of idle-increase solenoid
valve (A) and diode (B)
16.29 Disconnect vacuum hose, and
unscrew bolts (arrowed) to withdraw fuel
pressure regulator16.33 Access to idle speed control valve is
from underneath vehicle - unplug electrical
connector (arrowed) to check valve16.40 Unscrew bolts (arrowed) to remove
idle speed control valve
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General information
The engine electrical systems include all
ignition, charging and starting components.
Because of their engine-related functions,
these components are discussed separately
from body electrical devices such as the
lights, the instruments, etc (which are
included in Chapter 12).
Precautions
Always observe the following precautions
when working on the electrical system:
(a) Be extremely careful when servicing
engine electrical components. They are
easily damaged if checked, connected or
handled improperly.
(b) Never leave the ignition switched on for
long periods of time when the engine is
not running.
(c) Don’t disconnect the battery leads while
the engine is running.
(d) Maintain correct polarity when connecting
a battery lead from another vehicle during
jump starting - see the “Booster battery
(jump) starting” section at the front of this
manual.
(e) Always disconnect the negative lead first,
and reconnect it last, or the battery may
be shorted by the tool being used to
loosen the lead clamps (see illustration).
It’s also a good idea to review the safety-
related information regarding the engine
electrical systems located in the “Safety first!”
section at the front of this manual, before
beginning any operation included in this Chapter.
Battery disconnection
Several systems fitted to the vehicle require
battery power to be available at all times, either
to ensure their continued operation (such as
the clock) or to maintain control unit memories
(such as that in the engine management
system’s ECU) which would be wiped if the
battery were to be disconnected. Whenever thebattery is to be disconnected therefore, first
note the following, to ensure that there are no
unforeseen consequences of this action:
(a) First, on any vehicle with central locking, it
is a wise precaution to remove the key
from the ignition, and to keep it with you,
so that it does not get locked in if the
central locking should engage accidentally
when the battery is reconnected!
(b) The engine management system’s ECU will
lose the information stored in its memory -
referred to by Ford as the “KAM” (Keep-
Alive Memory) - when the battery is
disconnected. This includes idling and
operating values, and any fault codes
detected - in the case of the fault codes, if it
is thought likely that the system has
developed a fault for which the
corresponding code has been logged, the
vehicle must be taken to a Ford dealer for
the codes to be read, using the special
diagnostic equipment necessary for this (see
Chapter 6). Whenever the battery is
disconnected, the information relating to idle
speed control and other operating values will
have to be re-programmed into the unit’s
memory. The ECU does this by itself, but
until then, there may be surging, hesitation,
erratic idle and a generally inferior level of
performance. To allow the ECU to relearn
these values, start the engine and run it as
close to idle speed as possible until it
reaches its normal operating temperature,
then run it for approximately two minutes at
1200 rpm. Next, drive the vehicle as far as
necessary - approximately 5 miles of varied
driving conditions is usually sufficient - to
complete the relearning process.
(c) If the battery is disconnected while the
alarm system is armed or activated, the
alarm will remain in the same state when
the battery is reconnected. The same
applies to the engine immobiliser system
(where fitted).
(d) If a trip computer is in use, any
information stored in memory will be lost.
(e) If a Ford “Keycode” audio unit is fitted,
and the unit and/or the battery is
disconnected, the unit will not function
again on reconnection until the correct
security code is entered. Details of thisprocedure, which varies according to the
unit and model year, are given in the
“Ford Audio Systems Operating Guide”
supplied with the vehicle when new, with
the code itself being given in a “Radio
Passport” and/or a “Keycode Label” at
the same time. Ensure you have the
correct code before you disconnect the
battery. For obvious security reasons, the
procedure is not given in this manual. If
you do not have the code or details of the
correct procedure, but can supply proof
of ownership and a legitimate reason for
wanting this information, the vehicle’s
selling dealer may be able to help.
Devices known as “memory-savers” (or
“code-savers”) can be used to avoid some of
the above problems. Precise details vary
according to the device used. Typically, it is
plugged into the cigarette lighter, and is
connected by its own wires to a spare battery;
the vehicle’s own battery is then disconnected
from the electrical system, leaving the
“memory-saver” to pass sufficient current to
maintain audio unit security codes and ECU
memory values, and also to run permanently-
live circuits such as the clock, all the while
isolating the battery in the event of a short-
circuit occurring while work is carried out.
Warning: Some of these devices
allow a considerable amount of
current to pass, which can mean
that many of the vehicle’s systems are still
operational when the main battery is
disconnected. If a “memory-saver” is used,
ensure that the circuit concerned is
actually “dead” before carrying out any
work on it!
Note:See also the relevant Sections of
Chapter 1.
1Disconnect the battery leads, negative
(earth) lead first - see Section 1.
2Remove the battery hold-down clamp (see
illustrations).
3Lift out the battery. Be careful - it’s heavy.
4While the battery is out, inspect the tray for
corrosion (see Chapter 1).
2 Battery- removal and refitting
1 General information,
precautions and battery
disconnection
5•2 Engine electrical systems
1.2 Always disconnect battery - negative
(earth) lead first - to prevent the possibility
of short-circuits2.2A Unscrew hold-down nuts (one of two
arrowed) . . .2.2B . . . and withdraw hold-down clamp
to release battery
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5If you are renewing the battery, make sure
that you get one that’s identical, with the
same dimensions, amperage rating, cold
cranking rating, etc. Dispose of the old battery
in a responsible fashion. Most local authorities
have facilities for the collection and disposal
of such items - batteries contain sulphuric
acid and lead, and should not be simply
thrown out with the household rubbish!
6Refitting is the reverse of the removal
procedure.
Note:See also the relevant Sections of
Chapter 1.
1Periodically inspect the entire length of
each battery lead for damage, cracked or
burned insulation, and corrosion. Poor battery
lead connections can cause starting problems
and decreased engine performance.
2Check the lead-to-terminal connections at
the ends of the leads for cracks, loose wire
strands and corrosion. The presence of white,
fluffy deposits under the insulation at the lead
terminal connection is a sign that the lead is
corroded and should be renewed. Check the
terminals for distortion, missing clamp bolts,
and corrosion.
3When removing the leads, always
disconnect the negative lead first, and
reconnect it last (see Section 1). Even if only
the positive lead is being renewed, be sure to
disconnect the negative lead from the battery
first (see Chapter 1 for further information
regarding battery lead removal).
4Disconnect the old leads from the battery,
then trace each of them to their opposite
ends, and detach them from the starter
solenoid and earth terminals. Note the routing
of each lead, to ensure correct installation.
5If you are renewing either or both of the old
leads, take them with you when buying new
leads. It is vitally important that you replace
the leads with identical parts. Leads have
characteristics that make them easy to
identify: positive leads are usually red, larger
in cross-section, and have a larger-diameter
battery post clamp; earth leads are usually
black, smaller in cross-section and have a
slightly smaller-diameter clamp for the
negative post.
6Clean the threads of the solenoid or earth
connection with a wire brush to remove rust
and corrosion.
7Attach the lead to the solenoid or earth
connection, and tighten the mounting nut/bolt
securely.
8Before connecting a new lead to thebattery, make sure that it reaches the battery
post without having to be stretched.
9Connect the positive lead first, followed by
the negative lead.
General
The ignition system includes the ignition
switch, the battery, the crankshaft speed/
position sensor, the coil, the primary (low
tension/LT) and secondary (high tension/HT)
wiring circuits, and the spark plugs. On models
with automatic transmission, a separate
ignition module is also fitted, its functions
being incorporated in the ECU on models with
manual transmission. The ignition system is
controlled by the engine management
system’s Electronic Control Unit (ECU). Using
data provided by information sensors which
monitor various engine functions (such as
engine speed and piston position, intake air
mass and temperature, engine coolant
temperature, etc.), the ECU ensures a
perfectly-timed spark under all conditions (see
Chapter 6). Note:The ignition timing is under
the full control of the ECU, and cannot be
adjusted - see Section 8 for further details.
Precautions
When working on the ignition system, take
the following precautions:
(a) Do not keep the ignition switch on for more
than 10 seconds if the engine will not start.
(b) If a separate tachometer is ever required
for servicing work, consult a dealer
service department before buying a
tachometer for use with this vehicle -
some tachometers may be incompatible
with this ignition system - and always
connect it in accordance with the
equipment manufacturer’s instructions.
(c) Never connect the ignition coil terminals
to earth. This could result in damage to
the coil and/or the ECU or ignition module
(whichever is fitted).
(d) Do not disconnect the battery when the
engine is running.
(e) Make sure that the ignition module (where
fitted) is properly earthed.
(f) Refer to the warning at the beginning of
the next Section concerning HT voltage.
Warning: Because of the high
voltage generated by the ignition
system, extreme care should be
taken whenever an operation is performed
involving ignition components. This not
only includes the ignition module/ECU, coil
and spark plug (HT) leads, but related
components such as electrical connectors,
tachometer and other test equipment also.Note: This is an initial check of the “ignition
part” of the main engine management system,
to be carried out as part of the preliminary
checks of the complete engine management
system (see Chapter 6).
1If the engine turns over but won’t start,
disconnect the (HT) lead from any spark plug,
and attach it to a calibrated tester (available at
most automotive accessory shops). Connect
the clip on the tester to a good earth - a bolt
or metal bracket on the engine. If you’re
unable to obtain a calibrated ignition tester,
have the check carried out by a Ford dealer
service department or similar. Any other form
of testing (such as jumping a spark from the
end of an HT lead to earth) is not
recommended, because of the risk of
personal injury, or of damage to the
ECU/ignition module (see notes above and in
Section 4).
2Crank the engine and watch the end of the
tester to see if bright blue, well-defined sparks
occur.
3If sparks occur, sufficient voltage is
reaching the plug to fire it. Repeat the check
at the remaining plugs, to ensure that all leads
are sound and that the coil is serviceable.
However, the plugs themselves may be fouled
or faulty, so remove and check them as
described in Chapter 1.
4If no sparks or intermittent sparks occur,
the spark plug lead(s) may be defective -
check them as described in Chapter 1.
5If there’s still no spark, check the coil’s
electrical connector, to make sure it’s clean
and tight. Check for full battery voltage to the
coil at the connector’s centre terminal. The
coil is earthed through the ECU - do not
attempt to check this. Check the coil itself
(see Section 6). Make any necessary repairs,
then repeat the check again.
6The remainder of the system checks should
be left to a dealer service department or other
qualified repair facility, as there is a chance
that the ECU may be damaged if tests are not
performed properly.
Warning: Because of the high
voltage generated by the ignition
system, extreme care should be
taken whenever an operation is performed
involving ignition components. This not
only includes the ignition module/ECU, coil
and spark plug (HT) leads, but related
components such as electrical connectors,
tachometer and other test equipment also.
Check
1Having checked that full battery voltage is
available at the centre terminal of the coil’s
electrical connector (see Section 5),
disconnect the battery negative (earth) lead -
see Section 1.
2Unplug the coil’s electrical connector, if not
already disconnected.
6 Ignition coil -
removal and refitting
5 Ignition system - testing
4 Ignition system - general
information and precautions
3 Battery leads -
check and renewal
Engine electrical systems 5•3
5
Apply a light coat of battery
terminal corrosion inhibitor,
or petroleum jelly, to the
threads, to prevent future
corrosion.
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3Using an ohmmeter, measure the
resistance of the coil’s primary windings,
connecting the meter between the coil’s
terminal pins as follows. Measure first from
one outer pin to the centre pin, then from the
other outer pin to the centre. Compare your
readings with the coil primary resistance listed
in the Specifications Section at the beginning
of this Chapter.
4Disconnect the spark plug (HT) leads - note
their connections or label them carefully, as
described in Chapter 1. Use the meter to
check that there is continuity (ie, a resistance
corresponding to that of the coil secondary
winding) between each pair of (HT) lead
terminals; Nos 1 and 4 terminals are
connected by their secondary winding, as are
Nos 2 and 3. Now switch to the highest
resistance scale, and check that there is no
continuity between either pair of terminals and
the other - ie, there should be infinite
resistance between terminals 1 and 2, or 4
and 3 - and between any terminal and earth.
5If either of the above tests yield resistance
values outside the specified amount, or
results other than those described, renew the
coil. Any further testing should be left to a
dealer service department or other qualified
repair facility.
Removal and refitting
6Disconnect the battery negative (earth) lead
- see Section 1.
7Remove the air mass meter and resonator -
refer to Chapter 4.
8Unplug the electrical connector from each
side of the coil, then disconnect the spark
plug (HT) leads - note their connections or
label them carefully, as described in Chapter
1.
9Undo the two screws securing the EGR
pipe to the coil bracket, then remove the coil
mounting (Torx-type) screws. Withdraw the
coil assembly from the cylinder head (see
illustration).
10The suppressor can be unbolted from the
mounting bracket, if required; note that the
coil and bracket are only available as a single
unit.
11Refitting is the reverse of the removalprocedure. Ensure that the spark plug (HT)
leads are correctly reconnected, and tighten
the coil screws securely.
Note:See Chapter 6 for component location
illustrations.
1Disconnect the battery negative (earth) lead
- see Section 1.
2If better access is required, remove the
resonator (see Chapter 4).
3Unplug the electrical connector from the
module (see illustration).
4Remove the retaining screws, and detach
the module from the bulkhead mounting
bracket.
5Refitting is the reverse of the removal
procedure.
As noted in Section 4, the ignition timing is
controlled entirely by the ECU (acting with the
ignition module, on models with automatic
transmission), and cannot be adjusted. The
value quoted in the Specifications Section of
this Chapter is for reference only, and mayvary significantly if “checked” by simply
connecting a timing light to the system and
running the engine at idle speed.
Not only can the ignition timing not be
adjusted, it cannot be checked either, except
with the use of special diagnostic equipment
(see Chapter 6) - this makes it a task for a
Ford dealer service department.
Owners who are taking their vehicles
abroad should note that the ignition system is
set for the engine to use petrol of 95 RON
octane rating by fitting a “plug-in bridge” to
the service connector on the engine
compartment bulkhead (see illustration).
Removing the “plug-in bridge” retards the
ignition timing - by an unspecified value - to
allow the engine to run on 91 RON fuel. This
grade of fuel is the “Regular” or “Normal”
widely used abroad, but not at present
available in the UK. If you are taking the
vehicle abroad, seek the advice of a Ford
dealer (or of one of the motoring
organisations). This will ensure that you are
familiar with the grades of fuel you are likely to
find (and the sometimes confusing names for
those grades), and that the vehicle is set
correctly at all times for the fuel used. Note:
The octane ratings mentioned above are both,
of course, for unleadedpetrol. Do not use
leaded petrol at any time in a vehicle equipped
with a catalytic converter.
Checking
1See Section 4 of Chapter 6.
Removal and refitting
2Disconnect the battery negative (earth) lead
- see Section 1.
3Raise the front of the vehicle, and support it
securely on axle stands.
Warning: Do not place any part of
your body under a vehicle when
it’s supported only by a jack!
4Unplug the sensor’s electrical connector
(see illustration).
9 Crankshaft speed/position
sensor-
checking, removal and refitting
8 Ignition timing - checking
7 Ignition module (automatic
transmission models only) -
removal and refitting
5•4 Engine electrical systems
6.9 Unplug coil electrical connector (A),
suppressor connector (B), and spark
plug/HT leads (C), remove screws (D), then
undo Torx-type screws (E) to release
ignition coil assembly7.3 Separate ignition module is fitted to
automatic transmission models only - note
electrical connector (A) and retaining
screws (B)
8.3 Service connector (A) mounted on
engine compartment bulkhead is fitted with
“plug-in bridge” (B) to set engine to use
(unleaded) petrol of 95 RON octane rating9.4 Location of crankshaft speed/position
sensor - connector arrowed - in front of
cylinder block/crankcase
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5Undo the sensor’s retaining screw and
withdraw the sensor. The sensor’s bracket
cannot be unbolted from the cylinder
block/crankcase unless the transmission and
flywheel/driveplate have been removed (see
Chapter 2).
6Refitting is the reverse of the removal
procedure.
General information
The charging system includes the
alternator, an internal voltage regulator, a no-
charge (or “ignition”) warning light, the
battery, and the wiring between all the
components. The charging system supplies
electrical power for the ignition system, the
lights, the radio, etc. The alternator is driven
by the auxiliary drivebelt at the front (right-
hand end) of the engine.
The purpose of the voltage regulator is to
limit the alternator’s voltage to a preset value.
This prevents power surges, circuit overloads,
etc., during peak voltage output.
The charging system doesn’t ordinarily
require periodic maintenance. However, the
drivebelt, battery and wires and connections
should be inspected at the intervals outlined
in Chapter 1.
The dashboard warning light should come
on when the ignition key is turned to positions
“II” or “III”, then should go off immediately the
engine starts. If it remains on, or if it comes on
while the engine is running, there is a
malfunction in the charging system (see
Section 11). If the light does not come on
when the ignition key is turned, and the bulb is
sound (see Chapter 12), there is a fault in the
alternator.
Precautions
Be very careful when making electrical
circuit connections to a vehicle equipped with
an alternator, and note the following:
(a) When reconnecting wires to the alternator
from the battery, be sure to note the
polarity.
(b) Before using arc-welding equipment to
repair any part of the vehicle, disconnect
the wires from the alternator and the
battery terminals.
(c) Never start the engine with a battery
charger connected.
(d) Always disconnect both battery leads
before using a battery charger.
(e) The alternator is driven by an engine
drivebelt which could cause serious injury
if your hand, hair or clothes become
entangled in it with the engine running.
(f) Because the alternator is connected
directly to the battery, it could arc or
cause a fire if overloaded or shorted-out.
(g) Wrap a plastic bag over the alternator,
and secure it with rubber bands, beforesteam-cleaning or pressure-washing the
engine.
(h) Never disconnect the alternator terminals
while the engine is running.
1If a malfunction occurs in the charging
circuit, don’t automatically assume that the
alternator is causing the problem. First check
the following items:
(a) Check the tension and condition of the
auxiliary drivebelt - renew it if it is worn or
deteriorated (see Chapter 1).
(b) Ensure the alternator mounting bolts and
nuts are tight.
(c) Inspect the alternator wiring harness and
the electrical connections at the
alternator; they must be in good
condition, and tight.
(d) Check the large main fuses in the engine
compartment (see Chapter 12). If any is
blown, determine the cause, repair the
circuit and renew the fuse (the vehicle
won’t start and/or the accessories won’t
work if the fuse is blown).
(e) Start the engine and check the alternator
for abnormal noises - for example, a
shrieking or squealing sound may indicate
a badly-worn bearing or brush.
(f) Make sure that the battery is fully-charged
- one bad cell in a battery can cause
overcharging by the alternator.
(g) Disconnect the battery leads (negative
first, then positive). Inspect the battery
posts and the lead clamps for corrosion.
Clean them thoroughly if necessary (see
Section 3 and Chapter 1). Reconnect the
lead to the negative terminal.
(h) With the ignition and all accessories
switched off, insert a test light between
the battery negative post and the
disconnected negative lead clamp:
(1) If the test light does not come on, re-
attach the clamp and proceed to the next
step.
(2) If the test light comes on, there is a short
in the electrical system of the vehicle. The
short must be repaired before the
charging system can be checked.
(3) To find the short, disconnect the
alternator wiring harness:
(a) If the light goes out, the alternator is
at fault.
(b) If the light stays on, remove each fuse
until it goes out - this will tell you
which component is short-circuited.
2Using a voltmeter, check the battery
voltage with the engine off. It should be
approximately 12 volts.
3Start the engine and check the battery
voltage again. Increase engine speed until the
voltmeter reading remains steady; it should
now be approximately 13.5 to 14.6 volts.
4Switch on as many electrical accessories
(eg the headlights, heated rear window andheater blower) as possible, and check that the
alternator maintains the regulated voltage at
around 13 to 14 volts. The voltage may drop
and then come back up; it may also be
necessary to increase engine speed slightly,
even if the charging system is working
properly.
5If the voltage reading is greater than the
specified charging voltage, renew the voltage
regulator (see Section 13).
6If the voltmeter reading is less than that
specified, the fault may be due to worn
brushes, weak brush springs, a faulty voltage
regulator, a faulty diode, a severed phase
winding, or worn or damaged slip rings. The
brushes and slip rings may be checked (see
Section 13), but if the fault persists, the
alternator should be renewed or taken to an
auto-electrician for testing and repair.
1Disconnect the battery negative (earth) lead
- see Section 1.
2Remove the plenum chamber (see Chap-
ter 4).
3Unscrew the nuts to disconnect the wiring
from the alternator (see illustration). If
additional working clearance is required, undo
the right-hand of the three screws securing
the wiring “rail” to the rear of the inlet
manifold.
4Jack up and support the front right-hand
corner of the vehicle. Remove the auxiliary
drivebelt and the engine oil filter - place a wad
of rag to soak up the spilled oil (see Chap-
ter 1). Rather than refit a used filter, you are
advised to drain the engine oil, and then to fit
a new filter and refill the engine with clean oil
on reassembly. Where an engine oil cooler is
fitted, it may prove necessary to remove this
as well, to provide the clearance necessary to
remove the alternator (see Chapter 2, Part A).
5Unscrew the two bolts securing the power
steering system pipes to the right-hand side
of the front suspension subframe. With the
front wheels in the straight-ahead position,
disconnect the right-hand track rod end from
the steering knuckle (see Chapter 10).
6Remove the mounting bolts and nuts (one
12 Alternator-
removal and refitting
11 Charging system- testing
10 Charging system - general
information and precautions
Engine electrical systems 5•5
5
12.3 Disconnecting alternator wiring
procarmanuals.com

constantly monitors the oxygen content of the
exhaust gas. If the percentage of oxygen in
the exhaust gas is incorrect, an electrical
signal is sent to the ECU. The ECU processes
this information, and then sends a command
to the fuel injection system, telling it to change
the air/fuel mixture; the end result is an air/fuel
mixture ratio which is constantly maintained
at a predetermined ratio, regardless of driving
conditions. This happens in a fraction of a
second, and goes on almost all the time while
the engine is running - the exceptions are that
the ECU cuts out the system and runs the
engine on values pre-programmed
(“mapped”) into its memory both while the
oxygen sensor is reaching its normal
operating temperature after the engine has
been started from cold, and when the throttle
is fully open for full acceleration.
In the event of a sensor malfunction, a
back-up circuit will take over, to provide
driveability until the problem is identified and
fixed.
Precautions
(a) Always disconnect the power by
uncoupling the battery terminals - see
Section 1 of Chapter 5 - before removing
any of the electronic control system’s
electrical connectors.
(b) When installing a battery, be particularly
careful to avoid reversing the positive and
negative battery leads.
(c) Do not subject any components of the
system (especially the ECU) to severe
impact during removal or installation.
(d) Do not be careless during fault diagnosis.
Even slight terminal contact can invalidate
a testing procedure, and damage one of
the numerous transistor circuits.
(e) Never attempt to work on the ECU, to test
it (with any kind of test equipment), or to
open its cover.
(f) If you are inspecting electronic control
system components during rainy weather,
make sure that water does not enter any
part. When washing the engine
compartment, do not spray these parts or
their electrical connectors with water.
General
The various components of the fuel, ignition
and emissions control systems (not forgetting
the same ECU’s control of sub-systems such
as the radiator cooling fan, air conditioning
and automatic transmission, where
appropriate) are so closely interlinked that
diagnosis of a fault in any one component is
virtually impossible using traditional methods.
Working on simpler systems in the past, the
experienced mechanic may well have been
able to use personal skill and knowledge
immediately to pinpoint the cause of a fault, or
quickly to isolate the fault, by elimination;however, with an engine management system
integrated to this degree, this is not likely to
be possible in most instances, because of the
number of symptoms that could arise from
even a minor fault.
So that the causes of faults can be quickly
and accurately traced and rectified, the ECU
is provided with a built-in self-diagnosis
facility, which detects malfunctions in the
system’s components. When a fault occurs,
three things happen: the ECU identifies the
fault, stores a corresponding code in its
memory, and (in most cases) runs the system
using back-up values pre-programmed
(“mapped”) into its memory; some form of
driveability is thus maintained, to enable the
vehicle to be driven to a garage for attention.
Any faults that may have occurred are
indicated in the form of three-digit codes
when the system is connected (via the built-in
diagnosis or self-test connectors, as
appropriate) to special diagnostic equipment -
this points the user in the direction of the
faulty circuit, so that further tests can pinpoint
the exact location of the fault.
Given below is the procedure that would be
followed by a Ford technician to trace a fault
from scratch. Should your vehicle’s engine
management system develop a fault, read
through the procedure and decide how much
you can attempt, depending on your skill and
experience and the equipment available to
you, or whether it would be simpler to have
the vehicle attended to by your local Ford
dealer. If you are concerned about the
apparent complexity of the system, however,
remember the comments made in the fourth
paragraph of Section 1 of this Chapter; the
preliminary checks require nothing but care,
patience and a few minor items of equipment,
and may well eliminate the majority of faults.
(a) Preliminary checks
(b) Fault code read-out *
(c) Check ignition timing and base idle
speed. Recheck fault codes to establish
whether fault has been cured or not *
(d) Carry out basic check of ignition system
components. Recheck fault codes to
establish whether fault has been cured or
not *
(e) Carry out basic check of fuel system
components. Recheck fault codes to
establish whether fault has been cured or
not *
(f) If fault is still not located, carry out system
test *
Note:Operations marked with an asterisk
require special test equipment.
Preliminary checks
Note:When carrying out these checks to
trace a fault, remember that if the fault has
appeared only a short time after any part of
the vehicle has been serviced or overhauled,
the first place to check is where that work was
carried out, however unrelated it may appear,
to ensure that no carelessly-refitted
components are causing the problem.If you are tracing the cause of a “partial”
engine fault, such as lack of performance, in
addition to the checks outlined below, check
the compression pressures (see Part A of
Chapter 2) and bear in mind the possibility
that one of the hydraulic tappets might be
faulty, producing an incorrect valve clearance.
Check also that the fuel filter has been
renewed at the recommended intervals.
If the system appears completely dead,
remember the possibility that the
alarm/inhibitor system may be responsible.
1The first check for anyone without special
test equipment is to switch on the ignition,
and to listen for the fuel pump (the sound of
an electric motor running, audible from
beneath the rear seats); assuming there is
sufficient fuel in the tank, the pump should
start and run for approximately one or two
seconds, then stop, each time the ignition is
switched on. If the pump runs continuously all
the time the ignition is switched on, the
electronic control system is running in the
back-up (or “limp-home”) mode referred to by
Ford as “Limited Operation Strategy” (LOS).
This almost certainly indicates a fault in the
ECU itself, and the vehicle should therefore be
taken to a Ford dealer for a full test of the
complete system using the correct diagnostic
equipment; do not waste time trying to test
the system without such facilities.
2If the fuel pump is working correctly (or not
at all), a considerable amount of fault
diagnosis is still possible without special test
equipment. Start the checking procedure as
follows.
3Open the bonnet and check the condition
of the battery connections - remake the
connections or renew the leads if a fault is
found (Chapter 5). Use the same techniques
to ensure that all earth points in the engine
compartment provide good electrical contact
through clean, metal-to-metal joints, and that
all are securely fastened. (In addition to the
earth connection at the engine lifting eye and
that from the transmission to the
body/battery, there is one earth connection
behind each headlight assembly, and one
below the power steering fluid reservoir.)
4Referring to the information given in
Chapter 12 and in the wiring diagrams at the
back of this manual, check that all fuses
protecting the circuits related to the engine
management system are in good condition.
Fit new fuses if required; while you are there,
check that all relays are securely plugged into
their sockets.
5Next work methodically around the engine
compartment, checking all visible wiring, and
the connections between sections of the
wiring loom. What you are looking for at this
stage is wiring that is obviously damaged by
chafing against sharp edges, or against
moving suspension/transmission components
and/or the auxiliary drivebelt, by being
trapped or crushed between carelessly-
refitted components, or melted by being
forced into contact with hot engine castings,
3 Diagnosis system -
general information
6•4 Emissions control systems
procarmanuals.com

back again, as an assistant depresses the
accelerator pedal. If the valve shows any sign
of stiffness, sticking or otherwise-inhibited
movement (and the accelerator cable is
known from the previous check to be in good
condition), spray the throttle linkage with
penetrating lubricant, allow time for it to work,
and repeat the check; if no improvement is
obtained, the complete throttle housing must
be renewed (Chapter 4).
15Unclip the air cleaner cover, and check
that the air filter element and the crankcase
ventilation system filter are not clogged or
soaked. (A clogged air filter will obstruct the
intake air flow, causing a noticeable effect on
engine performance; a clogged crankcase
ventilation system filter will inhibit crankcase
“breathing”). Renew or clean the filter(s) as
appropriate; refer to the relevant Sections of
Chapter 1 for further information, if required.
Before refitting the air cleaner cover, check
that the air intake (located under the front left-
hand wing, opening behind the direction
indicator/headlight assembly) is clear. It
should be possible to blow through the intake,
or to probe it (carefully) as far as the rear of
the direction indicator light.
16Start the engine and allow it to idle.
Note:Working in the engine compartment
while the engine is running requires great care
if the risk of personal injury is to be avoided;
among the dangers are burns from contact
with hot components, or contact with moving
components such as the radiator cooling fan
or the auxiliary drivebelt. Refer to “Safety
first!” at the front of this manual before
starting, and ensure that your hands, and long
hair or loose clothing, are kept well clear of hot
or moving components at all times.
17Working from the air intake junction at the
inner wing panel, via the air cleaner assembly
and air mass meter, to the resonator, plenum
chamber, throttle housing and inlet manifold
(and including the various vacuum hoses and
pipes connected to these), check for air leaks.
Usually, these will be revealed by sucking or
hissing noises, but minor leaks may be traced
by spraying a solution of soapy water on to
the suspect joint; if a leak exists, it will be
shown by the change in engine note and the
accompanying air bubbles (or sucking-in of
the liquid, depending on the pressure
difference at that point). If a leak is found at
any point, tighten the fastening clamp and/or
renew the faulty components, as applicable.
18Similarly, work from the cylinder head, via
the manifold (and not forgetting the related
EGR and pulse-air system components) to the
tailpipe, to check that the exhaust system is
free from leaks. The simplest way of doing
this, if the vehicle can be raised and
supported safely and with complete security
while the check is made, is to temporarily
block the tailpipe while listening for the sound
of escaping exhaust gases; any leak should
be evident. If a leak is found at any point,
tighten the fastening clamp bolts and/or nuts,
renew the gasket, and/or renew the faultysection of the system, as necessary, to seal
the leak.
19It is possible to make a further check of
the electrical connections by wiggling each
electrical connector of the system in turn as
the engine is idling; a faulty connector will be
immediately evident from the engine’s
response as contact is broken and remade. A
faulty connector should be renewed to ensure
the future reliability of the system; note that
this may mean the renewal of that entire
section of the loom - see your local Ford
dealer for details.
20Switch off the engine. If the fault is not yet
identified, the next step is to check the
ignition voltages, using an engine analyser
with an oscilloscope - without such
equipment, the only tests possible are to
remove and check each spark plug in turn, to
check the spark plug (HT) lead connections
and resistances, and to check the
connections and resistances of the ignition
coil. Refer to the relevant Sections of
Chapters 1 and 5.
21The final step in these preliminary checks
would be to use an exhaust gas analyser to
measure the CO level at the exhaust tailpipe.This check cannot be made without special
test equipment - see your local Ford dealer for
details.
Fault code read-out
22As noted in the general comments at the
beginning of this Section, the preliminary
checks outlined above should eliminate the
majority of faults from the engine
management system. If the fault is not yet
identified, the next step is to connect a fault
code reader to the ECU, so that its self-
diagnosis facility can be used to identify the
faulty part of the system; further tests can
then be made to identify the exact cause of
the fault.
23In their basic form, fault code readers are
simply hand-held electronic devices, which
take data stored within an ECU’s memory and
display it when required as two- or three-digit
fault codes. The more sophisticated versions
now available can also control sensors and
actuators, to provide more effective testing;
some can store information, so that a road
test can be carried out, and any faults
encountered during the test can be displayed
afterwards.
6•6 Emissions control systems
3.26 Location and terminal identification of engine management system self-test,
diagnosis and service connectors
1 Power steering fluid reservoir
2 Diagnosis connector - for Ford diagnostic equipment FDS 2000
3 Self-test connector - for fault code read-out - pin 17 is output terminal, pin 48 is input
terminal, pin 40/60 is earth
4 Service connector - for octane adjustment
5 Plug-in bridge - to suit 95 RON fuel
procarmanuals.com

24Ford specify the use of their STAR (Self-
Test Automatic Readout) tester; most Ford
dealers should have such equipment, and the
staff trained to use it effectively. The only
alternatives are as follows:
(a) To obtain one of those proprietary readers
which can interpret EEC-IV three-digit
codes - at present, such readers are too
expensive for the DIY enthusiast, but are
becoming more popular with smaller
specialist garages.
(b) To use an analogue voltmeter, whereby
the stored codes are displayed as sweeps
of the voltmeter needle. This option limits
the operator to a read-out of any codes
stored - ie, there is no control of sensors
and/or actuators - but can still be useful in
pinpointing the faulty part of the engine
management system. The display is
interpreted as follows. Each code
(whether fault code or
command/separator) is marked by a
three-to-four second pause - code “538”
would therefore be shown as long (3 to
4 seconds) pause, five fast sweeps of the
needle, slight (1 second) pause, three fast
sweeps, slight pause, eight fast sweeps,
long pause.
(c) Owners without access to such
equipment must take the vehicle to a Ford
dealer, or to an expert who has similar
equipment and the skill to use it.
25Because of the variations in the design of
fault code readers, it is not possible to give
exact details of the sequence of tests; the
manufacturer’s instructions must be followed,
in conjunction with the codes given below.
The following ten paragraphs outline the
procedure to be followed using a version of
the Ford STAR tester, to illustrate the general
principles, as well as notes to guide the owner
using only a voltmeter.
26The vehicle must be prepared by applying
the handbrake, switching off the air
conditioning (where fitted) and any other
electrical loads (lights, heated rear window,
etc), then selecting neutral (manual
transmission) or the “P” position (automatic
transmission). Where the engine is required to
be running, it must be fully warmed-up to
normal operating temperature before the test
is started. Using any adaptors required,
connect the fault code reader to the system
via the (triangular, three-pin) self-test
connector on the right-hand end of the engine
compartment bulkhead (see illustration). If a
voltmeter is being used, connect its positive
lead to the battery positive terminal, and its
negative lead to the self-test connector’s
output terminal, pin 17. Have a pen and paper
ready to write down the codes displayed.
27Set the tester in operation. For the Ford
STAR tester, a display check will be carried
out and the test mode requirements must be
entered. If a voltmeter is being used, connect
a spare length of wire to earth the self-test
connector’s input terminal, pin 48. Be very
careful to ensure that you earth the correctterminal - the one with the white/green wire.
The first part of the test starts, with the
ignition switched on, but with the engine off.
On pressing the “Mem/test” button, the tester
displays “TEST” and the ready code “000”,
followed by a command code “010” - the
accelerator pedal must be fully depressed
within 10 seconds of the command code
appearing, or fault codes “576” or “577” will
appear when they are called up later. If a
voltmeter is being used, code “000” will not
appear (except perhaps as a flicker of the
needle) and “010” will appear as a single
sweep - to ensure correct interpretation of the
display, watch carefully for the interval
between the end of one code and the
beginning of the next, otherwise you will
become confused and misinterpret the read-
out.
28The tester will then display the codes for
any faults in the system at the time of the test.
Each code is repeated once; if no faults are
present, code “111” will be displayed. If a
voltmeter is being used, the pause between
repetitions will vary according to the
equipment in use and the number of faults in
the system, but was found to be
approximately 3 to 4 seconds - it may be
necessary to start again, and to repeat the
read-out until you are familiar with what you
are seeing.
29Next the tester will display code “010”
(now acting as a separator), followed by the
codes for any faults stored in the ECU’s
memory; if no faults were stored, code “111”
will be displayed.
30When prompted by the tester, the
operator must next depress the accelerator
pedal fully; the tester then checks several
actuators. Further test modes include a
“wiggle test” facility, whereby the operator
can check the various connectors as
described in paragraph 19 above (in this case,
any fault will be logged and the appropriate
code will be displayed), a facility for recalling
codes displayed, and a means for clearing the
ECU’s memory at the end of the test
procedure when any faults have been
rectified.
31The next step when using the Ford STAR
tester is to conduct a test with the engine
running. With the tester set in operation (see
paragraph 26 above) the engine is started and
allowed to idle. On pressing the “Mem/test”
button, the tester displays “TEST”, followed
by one of two codes, as follows.
32If warning code “998” appears, followed
by the appropriate fault code, switch off and
check as indicated the coolant temperature
sensor, the intake air temperature sensor, the
air mass meter, the throttle potentiometer
and/or their related circuits, then restart the
test procedure.
33If command code “020” appears, carry
out the following procedure within ten
seconds:
(a) Depress the brake pedal fully.
(b) Turn the steering to full-lock (either way)and centre it again, to produce a signal
from the power steering pressure switch -
if no signal is sent, fault code “521” will
be displayed.
(c) If automatic transmission is fitted, switch
the overdrive cancel button on and off,
then do the same for the
“Economy/Sport” mode switch.
(d) Wait for separator code “010” to be
displayed, then within 10 seconds,
depress the accelerator pedal fully,
increasing engine speed rapidly above
3000 rpm - release the pedal.
34Any faults found in the system will be
logged and displayed. Each code is repeated
once; if no faults are present, code “111” will
be displayed.
35When the codes have been displayed for
all faults logged, the ECU enters its “Service
Adjustment Programme”, as follows:
(a) The programme lasts for 2 minutes.
(b) The idle speed control valve is
deactivated, and the idle speed is set to
its pre-programmed (unregulated) value. If
the appropriate equipment is connected,
the base idle speed can be checked
(note, however, that it is not adjustable).
(c) The ignition timing can be checked if a
timing light is connected (note, however,
that it is not adjustable).
(d) Pressing the accelerator pedal fully at any
time during this period will execute a
cylinder balance test. Each injector in turn
is switched off, and the corresponding
decrease in engine speed is logged -
code “090” will be displayed if the test is
successful.
(e) At the end of the 2 minutes, the
completion of the programme is shown
by the engine speed briefly rising, then
returning to normal idling speed as
the idle speed control valve is
reactivated.
36As with the engine-off test, further test
modes include a “wiggle test” facility,
whereby the operator can check the various
connectors as described in paragraph 19
above (in this case, any fault will be logged
and the appropriate code will be displayed), a
facility for recalling codes displayed, and a
means for clearing the ECU’s memory at the
end of the test procedure when any faults
have been rectified. If equipment other than
the Ford STAR tester is used, the ECU’s
memory can be cleared by disconnecting the
battery - if this is not done, the code will
reappear with any other codes in the event of
subsequent trouble, but remember that other
systems with memory (such as the clock and
audio equipment) will also be affected. Should
it become necessary to disconnect the
battery during work on any other part of the
vehicle, first check to see if any fault codes
have been logged.
37Given overleaf are the possible codes,
their meanings, and where relevant, the action
to be taken as a result of a code being
displayed.
Emissions control systems 6•7
6
procarmanuals.com

Ignition timing and base idle
speed check
Note:The following procedure is a check only,
essentially of the ECU. Both the ignition timing
and the base idle speed are controlled by the
ECU. The ignition timing is not adjustable at
all; the base idle speed is set in production,
and should not be altered.
38If the fault code read-out (with any checks
resulting from it) has not eliminated the fault,
the next step is to check the ECU’s control of
the ignition timing and the base idle speed.
This task requires the use of a Ford STAR
tester (a proprietary fault code reader can be
used only if it is capable of inducing the ECU
to enter its “Service Adjustment Programme”),
coupled with an accurate tachometer and a
good-quality timing light. Without this
equipment, the task is not possible; the
vehicle must be taken to a Ford dealer for
attention.
39To make the check, apply the handbrake,
switch off the air conditioning (where fitted)
and any other electrical loads (lights, heated
rear window, etc), then select neutral (manual
transmission) or the “P” position (automatic
transmission). Start the engine, and warm it
up to normal operating temperature. The
radiator electric cooling fan must be running
continuously while the check is made; this
should be activated by the ECU, when
prompted by the tester. Switch off the engine,
and connect the test equipment as directed
by the manufacturer - refer to paragraph 26
above for details of STAR tester connection.
40Raise and support the front of the vehicle
securely, and remove the auxiliary drivebelt
cover (see Chapter 1). Emphasise the two
pairs of notches in the inner and outer rims of
the crankshaft pulley, using white paint. Note
that an ignition timing reference mark is not
provided on the pulley - in the normal
direction of crankshaft rotation (clockwise,
seen from the right-hand side of the vehicle)
the first pair of notches are irrelevant to the
vehicles covered in this manual, while the
second pair indicate Top Dead Centre (TDC)
when aligned with the rear edge of the raised
mark on the sump; when checking the ignition
timing, therefore, the (rear edge of the) sumpmark should appear just before the TDC
notches (see Part A of Chapter 2, Section 4,
for further information if required).
41Start the engine and allow it to idle. Work
through the engine-running test procedure
until the ECU enters its “Service Adjustment
Programme” - see paragraph 35 above.
42Use the timing light to check that the
timing marks appear approximately as
outlined above at idle speed. Do not spend
too much time on this check; if the timing
appears to be incorrect, the system may have
a fault, and a full system test must be carried
out (see below) to establish its cause.
43Using the tachometer, check that the
base idle speed is as given in the
Specifications Section of Chapter 4.
44If the recorded speed differs significantly
from the specified value, check for air leaks,
as described in the preliminary checks
(paragraphs 15 to 18 above), or any other
faults which might cause the discrepancy.
45The base idle speed is set in production
by means of an air bypass screw (located in
the front right-hand corner of the throttle
housing) which controls the amount of air that
is allowed to pass through a bypass passage,
past the throttle valve when it is fully closed in
the idle position; the screw is then sealed with
a white tamperproof plug (see illustration). In
service, the idle speed is controlled by the
ECU, which has the ability to compensate for
engine wear, build-up of dirt in the throttle
housing, and other factors which might
require changes in idle speed. The air bypass
screw setting should not, therefore, be
altered. If any alterations are made, a blue
tamperproof plug must be fitted, and the
engine should be allowed to idle for at least
five minutes on completion, so that the ECU
can re-learn its idle values.
46When both checks have been made and
the “Service Adjustment Programme” is
completed, follow the tester instructions to
return to the fault code read-out, and
establish whether the fault has been cured or
not.
Basic check of ignition system
47If the checks so far have not eliminated
the fault, the next step is to carry out a basic
check of the ignition system components,
using an engine analyser with an oscilloscope
- without such equipment, the only tests
possible are to remove and check each spark
plug in turn, to check the spark plug (HT) lead
connections and resistances, and to check
the connections and resistances of the
ignition coil. Refer to the relevant Sections of
Chapters 1 and 5.
Basic check of fuel system
48If the checks so far have not eliminated
the fault, the next step is to carry out a basic
check of the fuel system components.
49Assuming that the preliminary checks
have established that the fuel pump is
operating correctly, that the fuel filter isunlikely to be blocked, and also that there are
no leaks in the system, the next step is to
check the fuel pressure (see Chapter 4). If this
is correct, check the injectors (see Chapter 4)
and the Positive Crankcase Ventilation system
(see Chapter 1).
System test
50The final element of the Ford testing
procedure is to carry out a system test, using
a break-out box - this is a device that is
connected between the ECU and its electrical
connector, so that the individual circuits
indicated by the fault code read-out can be
tested while connected to the system, if
necessary with the engine running. In the case
of many of the system’s components, this
enables their output voltages to be measured
- a more accurate means of testing.
51In addition to the break-out box and the
adaptors required to connect it, several items
of specialist equipment are needed to
complete these tests. This puts them quite
beyond the scope of many smaller dealers, let
alone the DIY owner; the vehicle should be
taken to a Ford dealer for attention.
Note:This Section is concerned principally
with the sensors which give the ECU the
information it needs to control the various
engine management sub-systems - for further
details of those systems and their other
components, refer to the relevant Chapter of
this manual.
General
ECU (Electronic Control Unit)
1This component is the heart of the entire
engine management system, controlling the
fuel injection, ignition and emissions control
systems. It also controls sub-systems such as
the radiator cooling fan, air conditioning and
automatic transmission, where appropriate.
Refer to Section 2 of this Chapter for an
illustration of how it works.
Air mass meter
2This uses a “hot-wire” system, sending the
ECU a constantly-varying (analogue) voltage
signal corresponding to the mass of air
passing into the engine. Since air mass varies
with temperature (cold air being denser than
warm), measuring air mass provides the ECU
with a very accurate means of determining the
correct amount of fuel required to achieve the
ideal air/fuel mixture ratio.
Crankshaft speed/position sensor
3This is an inductive pulse generator bolted
(in a separate bracket) to the cylinder
block/crankcase, to scan the ridges between
36 holes machined in the inboard (right-hand)
face of the flywheel/driveplate. As each ridge
4 Information sensors -
general information, testing,
removal and refitting
6•10 Emissions control systems
3.45 Throttle housing air bypass screw is
sealed on production with a white
tamperproof plug (arrowed)
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