FORD MONDEO 1993 Service Repair Manual

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
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6•8 Emissions control systems
Code Meaning Action
000 Ready for test -
010 Command/separator code Depress accelerator pedal fully, then release
020 Command code Depress brake pedal fully, then release
10 Cylinder No 1 low During cylinder balance test
20 Cylinder No 2 low During cylinder balance test
30 Cylinder No 3 low During cylinder balance test
40 Cylinder No 4 low During cylinder balance test
90 Cylinder balance test successful -
111 No faults found -
112 to 114 Intake air temperature sensor Check component (Section 4 of this Chapter)116 to 118 Coolant temperature sensor - normal If fault still exists on reaching normal operating temperature, check
operating temperature not reached component (Chapter 3)
121 to 125 Throttle potentiometer Check component (Section 4 of this Chapter)129 Incorrect response from air mass
meter while conducting test Repeat test
136, 137 Oxygen sensor Check component (Section 4 of this Chapter)
139 Oxygen sensor Check component (Section 4 of this Chapter)
144 Oxygen sensor Check component (Section 4 of this Chapter)
157 to 159 Air mass meter Check component (Section 4 of this Chapter)
167 Incorrect response from throttle
potentiometer while conducting test Repeat test
171 Oxygen sensor Check component (Section 4 of this Chapter)
172 Oxygen sensor - mixture too weak Check component (Section 4 of this Chapter)
173 Oxygen sensor - mixture too rich Check component (Section 4 of this Chapter)
174, 175 Oxygen sensor Check component (Section 4 of this Chapter)
176 Oxygen sensor - mixture too weak Check component (Section 4 of this Chapter)
177 Oxygen sensor - mixture too rich Check component (Section 4 of this Chapter)
178 Oxygen sensor Check component (Section 4 of this Chapter)
179 Fuel system - mixture too weak Check EGR valve (Section 6 of this Chapter)
181 Fuel system - mixture too rich Check EGR valve (Section 6 of this Chapter)
182 Idle mixture too weak Check idle speed control valve (Chapter 4)
183 Idle mixture too rich If mixture OK, check fuel system (see below)
184, 185 Air mass meter Check component (Section 4 of this Chapter)
186 Injector opening time (pulse width) too long Carry out system test (see below)
187 Injector opening time (pulse width) too short Carry out system test (see below)
188 Oxygen sensor - mixture too weak Check component (Section 4 of this Chapter)
189 Oxygen sensor - mixture too rich Check component (Section 4 of this Chapter)191 Idle mixture too weak Check EGR valve (Section 6 of this Chapter) and idle speed control valve
(Chapter 4)
192 Idle mixture too rich Check EGR valve (Section 6 of this Chapter) and idle speed control valve
(Chapter 4)
194, 195 Oxygen sensor Check component (Section 4 of this Chapter)
211 No ignition signal to ECU Carry out system test (see below)
212 Tachometer circuit Carry out system test (see below)
213 No ignition signal from ECU Carry out system test (see below)
214 Camshaft position sensor Check component (Section 4 of this Chapter)
215 to 217 Ignition coil Carry out system test (see below)
218, 222 Tachometer circuit Carry out system test (see below)
226 ECU/ignition module pulse Carry out system test (see below)
227 Crankshaft speed/position sensor Check component (Chapter 5)
228 Ignition module/ignition coil winding 1 Carry out system test (see below)
229 Ignition module/ignition coil winding 2 Carry out system test (see below)
231 Ignition module/ignition coil winding 3 Carry out system test (see below)
232 Ignition coil primary windings Carry out system test (see below)
233 Ignition module Carry out system test (see below)
234 to 237 Ignition coil primary windings Carry out system test (see below)
238 Ignition module/ignition coil primary windings Carry out system test (see below)
239 No ignition signal to ECU on cranking Carry out system test (see below)
241 Incorrect response from ECU and/or
ignition module while conducting test Repeat test
243 Ignition coil failure Carry out system test (see below)
311 to 316 Pulse-air system Carry out system test (see below)326 EGR system exhaust gas pressure
differential sensor Check component (Section 6 of this Chapter)
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Code Meaning Action327 EGR system exhaust gas pressure
differential sensor or solenoid valve Check components (Section 6 of this Chapter)
328 EGR system solenoid valve Check component (Section 6 of this Chapter)
332 EGR valve not opening Check component (Section 6 of this Chapter)
334 EGR system solenoid valve Check component (Section 6 of this Chapter)335 EGR system exhaust gas pressure
differential sensor Check component (Section 6 of this Chapter)
336 Exhaust gas pressure too high Check system (Section 6 of this Chapter)337 EGR system exhaust gas pressure
differential sensor or solenoid valve Check components (Section 6 of this Chapter)
338, 339 Coolant temperature sensor Carry out system test (see below)
341 Service connector earthed Unplug connector and repeat test - reconnect on completion
411 Engine speed too low during test Check for air leaks, then repeat test
412 Engine speed too high during test Check for air leaks, then repeat test
413 to 416 Idle speed control valve Check component (Chapter 4, Section 16)
452 Vehicle speed sensor Check component (Section 4 of this Chapter)
511, 512 ECU memory Check whether battery was disconnected, then check fuse 11 - if fault still
exists, renew ECU (Section 6 of this Chapter)
513 ECU reference voltage Carry out system test (see below)
519, 521 Power steering pressure switch not Check component is fitted and connected, then repeat test - if fault still
operated during test exists, carry out system test (see below)
522, 523 Selector lever position sensor Check component (Chapter 7, Part B)
536 Brake on/off switch not activated
during test Repeat test
538 Operator error during test Repeat test
539 Air conditioning switched on during test Switch off and repeat test
542, 543 Fuel pump circuit Carry out system test (see below)
551 Idle speed control valve circuit Carry out system test (see below)
552 Pulse-air system circuit Carry out system test (see below)
556 Fuel pump circuit Check fuel pump relay - if fault still exists, carry out system test (see below)
558 EGR system solenoid valve circuit Carry out system test (see below)
563 Radiator (high-speed) electric
cooling fan relay and/or circuit Carry out system test (see below)564 Radiator electric cooling fan relay
and/or circuit Carry out system test (see below)
565 Charcoal canister-purge solenoid valve Check component (Section 5 of this Chapter)573 Radiator electric cooling fan relay
and/or circuit Carry out system test (see below)
574 Radiator (high-speed) electric
cooling fan relay and/or circuit Carry out system test (see below)575 Fuel pump and/or fuel cut-off
switch circuits Carry out system test (see below)
576, 577 Accelerator pedal not depressed fully during
test procedure - automatic transmission
kickdown not activated Repeat test
621 Automatic transmission shift solenoid 1 circuit Refer to Chapter 7, Part B
622 Automatic transmission shift solenoid 2 circuit Refer to Chapter 7, Part B
624 Automatic transmission electronic
pressure control solenoid Refer to Chapter 7, Part B
625 Automatic transmission electronic
pressure control solenoid circuit Refer to Chapter 7, Part B
629 Automatic transmission torque
converter clutch solenoid Refer to Chapter 7, Part B
634 Selector lever position sensor circuit Check component (Chapter 7, Part B)
635, 637 Automatic transmission fluid temperature sensor Refer to Chapter 7, Part B
639 Automatic transmission speed sensor Refer to Chapter 7, Part B
645 Automatic transmission 1st speed Refer to Chapter 7, Part B
646 Automatic transmission 2nd speed Refer to Chapter 7, Part B
647 Automatic transmission 3rd speed Refer to Chapter 7, Part B
648 Automatic transmission 4th speed Refer to Chapter 7, Part B
653 Automatic transmission overdrive
cancel button and “Economy/Sport”
mode switch not operated during test Repeat test
998 Warning code Check fault(s) indicated by subsequent code(s)
Emissions control systems 6•9
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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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passes the sensor tip, a signal is generated,
which is used by the ECU to determine engine
speed.
4The ridge between the 35th and 36th holes
(corresponding to 90° BTDC) is missing - this
step in the incoming signals is used by the
ECU to determine crankshaft (ie, piston)
position.
Camshaft position sensor
5This is bolted to the rear left-hand end of
the cylinder head, to register with a lobe on
the inlet camshaft. It functions in the same
way as the crankshaft speed/position sensor,
producing a series of pulses (corresponding
to No 1 cylinder at 46° ATDC); this gives the
ECU a reference point, to enable it to
determine the firing order, and operate the
injectors in the appropriate sequence.
Coolant temperature sensor
6This component, which is screwed into the
top of the thermostat housing, is an NTC
(Negative Temperature Coefficient) thermistor
- that is, a semi-conductor whose electrical
resistance decreases as its temperature
increases. It provides the ECU with a
constantly-varying (analogue) voltage signal,
corresponding to the temperature of the
engine coolant. This is used to refine the
calculations made by the ECU, when
determining the correct amount of fuel
required to achieve the ideal air/fuel mixture
ratio.
Intake air temperature sensor
7This component, which is screwed into the
underside of the air intake resonator, is also an
NTC thermistor - see the previous paragraph -
providing the ECU with a signal corresponding
to the temperature of air passing into the
engine. This is used to refine the calculations
made by the ECU, when determining the
correct amount of fuel required to achieve the
ideal air/fuel mixture ratio.
Throttle potentiometer
8This is mounted on the end of the throttle
valve spindle, to provide the ECU with a
constantly-varying (analogue) voltage signal
corresponding to the throttle opening. This
allows the ECU to register the driver’s input
when determining the amount of fuel required
by the engine.
Vehicle speed sensor
9This component is a Hall-effect generator,
mounted on the transmission’s speedometer
drive. It supplies the ECU with a series of
pulses corresponding to the vehicle’s road
speed, enabling the ECU to control features
such as the fuel shut-off on the overrun, and
to provide information for the trip computer,
adaptive damping and cruise control systems
(where fitted).
Power steering pressure switch
10This is a pressure-operated switch,
screwed into the power steering system’shigh-pressure pipe. Its contacts are normally
closed, opening when the system reaches the
specified pressure - on receiving this signal,
the ECU increases the idle speed, to
compensate for the additional load on the
engine.
Exhaust gas pressure differential
sensor
11This component measures the difference
in pressure of the exhaust gases across a
venturi (restriction) in the Exhaust Gas
Recirculation (EGR) system’s pipe, and sends
the ECU a voltage signal corresponding to the
pressure difference.
Oxygen sensor
12The oxygen sensor in the exhaust system
provides the ECU with constant feedback -
“closed-loop” control - which enables it to
adjust the mixture to provide the best possible
conditions for the catalytic converter to
operate.
13The sensor has a built-in heating element
which is controlled by the ECU, in order to
bring the sensor’s tip to an efficient operating
temperature as rapidly as possible. The
sensor’s tip is sensitive to oxygen, and sends
the ECU a varying voltage depending on the
amount of oxygen in the exhaust gases. If the
intake air/fuel mixture is too rich, the exhaust
gases are low in oxygen, so the sensor sends
a low-voltage signal, the voltage rising as the
mixture weakens and the amount of oxygen in
the exhaust gases rises. Peak conversion
efficiency of all major pollutants occurs if the
intake air/fuel mixture is maintained at the
chemically-correct ratio for the complete
combustion of petrol, of 14.7 parts (by weight)
of air to 1 part of fuel (the “stoichiometric”
ratio). The sensor output voltage alters sharply
around this point, the ECU using the signal
change as a reference point, and correcting
the air/fuel mixture by altering the fuel injector
pulse width.
Air conditioning system
14Two pressure-operated switches and the
compressor clutch solenoid are connected to
the ECU, to enable it to determine how the
system is operating. The ECU can increase
idle speed or switch off the system, as
necessary, so that normal vehicle operation
and driveability are not impaired. See Chapter
3 for further details, but note that diagnosis
and repair should be left to a dealer service
department or air conditioning specialist.
Automatic transmission
15In addition to the driver’s controls, the
transmission has a speed sensor, a fluid
temperature sensor (built into the solenoid
valve unit), and a selector lever position
sensor. All of these are connected to the ECU,
to enable it to control the transmission
through the solenoid valve unit. See Part B of
Chapter 7 for further details.
Testing
ECU (Electronic Control Unit)
16 Do notattempt to “test” the ECU with any
kind of equipment. If it is thought to be faulty,
take the vehicle to a Ford dealer for the entire
electronic control system to be checked using
the proper diagnostic equipment. Only if all
other possibilities have been eliminated should
the ECU be considered at fault, and replaced.
Air mass meter
17Testing of this component is beyond the
scope of the DIY mechanic, and should be left
to a Ford dealer.
Crankshaft speed/position sensor
18Unplug the electrical connector from the
sensor.
19Using an ohmmeter, measure the
resistance between the sensor terminals.
Compare this reading to the one listed in the
Specifications Section at the beginning of this
Chapter. If the indicated resistance is not
within the specified range, renew the sensor.
20Plug in the sensor’s electrical connector
on completion.
Camshaft position sensor
21The procedure is as described in
paragraphs 18 to 20 above.
Coolant temperature sensor
22Refer to Chapter 3.
Intake air temperature sensor
23Unplug the electrical connector from the
sensor.
24Using an ohmmeter, measure the
resistance between the sensor terminals.
Depending on the temperature of the sensor
tip, the resistance measured will vary, but it
should be within the broad limits given in the
Specifications Section of this Chapter. If the
sensor’s temperature is varied - by placing it
in a freezer for a while, or by warming it gently
- its resistance should alter accordingly.
25If the results obtained show the sensor to
be faulty, renew it.
Throttle potentiometer
26Remove the plenum chamber (see
Chapter 4) and unplug the potentiometer’s
electrical connector.
27Using an ohmmeter, measure the
resistance between the unit’s terminals - first
between the centre terminal and one of the
outer two, then from the centre to the
remaining outer terminal. The resistance
should be within the limits given in the
Specifications Section of this Chapter, and
should alter smoothlyas the throttle valve is
moved from the fully-closed (idle speed)
position to fully open and back again.
28If the resistance measured is significantly
different from the specified value, if there are
any breaks in continuity, or if the reading
fluctuates erratically as the throttle is
operated, the potentiometer is faulty, and
must be renewed.
Emissions control systems 6•11
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Vehicle speed sensor
29Testing of this component is beyond the
scope of the DIY mechanic, and should be left
to a Ford dealer.
Power steering pressure switch
30Unplug the electrical connector from the
sensor.
31Using an ohmmeter, measure the
resistance between the switch terminals. With
the engine switched off, or idling with the
roadwheels in the straight-ahead position,
little or no resistance should be measured.
With the engine running and the steering on
full-lock, the pressure increase in the system
should open the switch contacts, so that
infinite resistance is now measured.
32If the results obtained show the switch to
be faulty, renew it.
Exhaust gas pressure differential
sensor
33Testing of this component is beyond the
scope of the DIY mechanic, and should be left
to a Ford dealer.
Oxygen sensor
34Testing of this component can be done
only by attaching special diagnostic
equipment to the sensor wiring, and checking
that the voltage varies from low to high values
when the engine is running; do notattempt to
“test” any part of the system with anything
other than the correct test equipment. This is
beyond the scope of the DIY mechanic, and
should be left to a Ford dealer.
Removal and refitting
General
35Before disconnecting any of these
components, always disconnect the power by
uncoupling the battery terminals, negative
(earth) lead first - see Section 1 of Chapter 5.
ECU (Electronic Control Unit)
Note:The ECU is fragile. Take care not to
drop it or subject it to any other kind of
impact, and do not subject it to extremes of
temperature, or allow it to get wet.
36Carefully prise the power steering fluid
reservoir upwards out of its clip on the
suspension mounting. Unscrew the ECU
connector’s retaining bolt, and unplug the
connector (see illustrations).
37Working in the passenger compartment,
unscrew the retaining bolt and withdraw the
mounting bracket (see illustration).
38Lifting the ECU to release it from the
bulkhead carrier bracket, withdraw the unit
(see illustration).
39Refitting is the reverse of the removal
procedure. Whenever the ECU (or battery) is
disconnected, the information relating to idle
speed control and other operating values will
be lost from its memory until the unit has re-
programmed itself; until then, there may be
surging, hesitation, erratic idle and a
generally-inferior level of performance. To
allow the ECU to re-learn these values, start
the engine and run it as close to idle speed as
possible until it reaches its normal operatingtemperature, 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 re-learning process.
Air mass meter
40Releasing its wire clip, unplug the meter’s
electrical connector (see illustration).
41Release the clips and lift the air cleaner
cover, then release the two smaller clips and
detach the meter from the cover (see
illustration).
42Slacken the clamp securing the meter to
the resonator hose, and withdraw the meter.
43Refitting is the reverse of the removal
procedure. Ensure that the meter and air
cleaner cover are seated correctly and securely
fastened, so that there are no air leaks.
Crankshaft speed/position sensor
44Refer to Chapter 5.
Camshaft position sensor
45Remove the air mass meter and resonator
(refer to Chapter 4) to gain access to the
sensor (see illustration). Release the fuel
feed and return hoses from their clip.
46Releasing its wire clip, unplug the
sensor’s electrical connector. Remove the
retaining screw, and withdraw the sensor from
the cylinder head; be prepared for slight oil
loss.
47Refitting is the reverse of the removal
procedure, noting the following points:
6•12 Emissions control systems
4.36A Unclip and lift power steering fluid
reservoir - take care not to spill fluid . . .4.36B . . . unscrew bolt (arrowed) to
release ECU’s electrical connector4.37 Unscrew retaining bolt and withdraw
ECU’s mounting bracket . . .
4.40 Unplugging the air mass meter’s
electrical connector . . .4.38 . . . then lift ECU to disengage it, and
withdraw it4.41 . . . release clips to separate meter
from air cleaner cover
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(a) Apply petroleum jelly or clean engine oil
to the sensor’s sealing O-ring.
(b) Locate the sensor fully in the cylinder
head, and wipe off any surplus lubricant
before securing it.
(c) Tighten the screw to the specified torque
wrench setting.
Coolant temperature sensor
48Refer to Chapter 3, Section 6.
Intake air temperature sensor
49Remove the air mass meter and resonator
(refer to Chapter 4) to gain access to the
sensor (see illustration).
50Releasing its clip, unplug the sensor’s
electrical connector, then unscrew the sensor
from the resonator.
51Refitting is the reverse of the removal
procedure. Tighten the sensor to the specified
torque wrench setting; if it is overtightened, its
tapered thread may crack the resonator.
Throttle potentiometer
52Remove the plenum chamber (see
Chapter 4). Releasing its wire clip, unplug the
large electrical connector (next to the fuel
pressure regulator).
53Releasing its wire clip, unplug the
potentiometer’s electrical connector. Remove
the retaining screws, and withdraw the unit
from the throttle housing (see illustration). Do
notforce the sensor’s centre to rotate past itsnormal operating sweep; the unit will be
seriously damaged.
54Refitting is the reverse of the removal
procedure, noting the following points:
(a) Ensure that the potentiometer is correctly
orientated, by locating its centre on the D-
shaped throttle shaft (throttle closed), and
aligning the potentiometer body so that
the bolts pass easily into the throttle
housing.
(b) Tighten the screws evenly and securely
(but do not overtighten them, or the
potentiometer body will be cracked).
Vehicle speed sensor
55The sensor is mounted at the base of the
speedometer drive cable, and is removed with
the speedometer drive pinion (see
illustration). Refer to the relevant Section of
Chapter 7, Part A or B, as applicable.
Power steering pressure switch
56Releasing its clip, unplug the switch’s
electrical connector, then unscrew the switch
(see illustration). Place a wad of rag
underneath, to catch any spilt fluid. If a
sealing washer is fitted, renew it if it is worn or
damaged.
57Refitting is the reverse of the removal
procedure; tighten the switch securely, then
top-up the fluid reservoir (see Chapter 1) to
replace any fluid lost from the system, and
bleed out any trapped air (see Chapter 10,
Section 33).
Exhaust gas pressure differential
sensor
Note:See also Section 6, illustration 6.21.
58If better access is required, remove the
resonator (see Chapter 4).
59Releasing its wire clip, unplug the
sensor’s electrical connector. Remove the
two retaining screws, withdraw the unit from
the bulkhead mounting bracket, then
disconnect the two vacuum hoses. Note that
the hoses are of different sizes, to ensure that
they cannot be mixed up on reconnection.
60Check the condition of both hoses, and
renew them if necessary (see Chapter 1).
61Refitting is the reverse of the removal
procedure. Ensure that the hoses are securely
connected to the correct unions.
Oxygen sensor
Note:The sensor is delicate, and will not work
if it is dropped or knocked, if its power supply
is disrupted, or if any cleaning materials are
used on it.
62Release the sensor’s electrical connector
from its bracket on the engine/transmission
front mounting, and unplug it to disconnect
the sensor (see illustration).
63Raising and supporting the front of the
vehicle if required to remove the sensor from
underneath, unscrew the sensor from the
exhaust system front downpipe; collect the
sealing washer (where fitted).
64On refitting, clean the sealing washer
Emissions control systems 6•13
6
4.56 Power steering pressure switch is
screwed into pipe at right-hand rear end of
engine4.62 Oxygen sensor is screwed into
exhaust system front downpipe . . .
4.49 Intake air temperature sensor
(arrowed) is screwed into underside of air
intake resonator4.53 Throttle potentiometer is secured by
two screws (arrowed)
4.55 Vehicle speed sensor “A”, with its
electrical connector “B”
4.45 Camshaft position sensor is located
at left-hand rear end of cylinder head
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(where fitted) and renew it if it is damaged or
worn. Apply a smear of anti-seize compound
to the sensor’s threads, to prevent them from
welding themselves to the downpipe in
service. Refit the sensor, tightening it to its
specified torque wrench setting; a slotted
socket will be required to do this (see
illustration). Reconnect the wiring and refit
the connector plug.
General description
1This system is fitted to minimise the escape
of unburned hydrocarbons into the
atmosphere. The fuel tank filler cap is sealed,
and a charcoal canister is mounted
underneath the tank, to collect and store
petrol vapours generated in the tank when the
vehicle is parked. When the engine is running,
the vapours are cleared from the canister
(under the control of the ECU via the canister-
purge solenoid valve) into the inlet tract, to be
burned by the engine during normal
combustion - see illustration 2.1A.
2To ensure that the engine runs correctly
when it is cold and/or idling, and to protect
the catalytic converter from the effects of an
over-rich mixture, the canister-purge solenoid
valve is not opened by the ECU until the
engine is fully warmed-up and running under
part-load; the solenoid valve is then switched
on and off, to allow the stored vapour to pass
into the inlet.
Checking
3Poor idle, stalling and poor driveability can
be caused by an inoperative canister-purge
solenoid valve, a damaged canister, split or
cracked hoses, or hoses connected to the
wrong fittings. Check the fuel filler cap for a
damaged or deformed gasket.
4Fuel loss or fuel odour can be caused by
liquid fuel leaking from fuel lines, a cracked or
damaged canister, an inoperative canister-purge solenoid valve, and disconnected,
misrouted, kinked or damaged vapour or
control hoses.
5Inspect each hose attached to the canister
for kinks, leaks and cracks along its entire
length. Repair or renew as necessary.
6Inspect the canister. If it is cracked or
damaged, renew it. Look for fuel leaking from
the bottom of the canister. If fuel is leaking,
renew the canister, and check the hoses and
hose routing.
7If the canister-purge solenoid valve is
thought to be faulty, unplug its electrical
connector and disconnect its vacuum hoses.
Connect a battery directly across the valve
terminals. Check that air can flow through the
valve passages when the solenoid is thus
energised, and that nothing can pass when the
solenoid is not energised. Alternatively,
connect an ohmmeter to measure the
resistance across the solenoid terminals, and
compare this reading to the one listed in the
Specifications Section at the beginning of this
Chapter. Renew the solenoid valve if it is faulty.
8Further testing should be left to a dealer
service department.
Component renewal
Charcoal canister-purge solenoid
valve
9If better access is required, remove the
plenum chamber (see Chapter 4). Disconnect
the battery negative (earth) lead - see Sec-
tion 1 of Chapter 5.10Unplug the valve’s electrical connector
(see illustration). Unclip the valve from the
bulkhead, then disconnect its vacuum hoses
and withdraw it.
11Refitting is the reverse of the removal
procedure.
Charcoal canister - Saloon and
Hatchback models
Note:Read through this procedure carefully
before starting work, and ensure that the
equipment is available that is required to carry
it out safely and with minimum risk of damage,
and to align the crossmember with sufficient
accuracy on reassembly.
12Remove the fuel tank (see Chapter 4).
13Ensure that the rear of the vehicle’s body
is supported securely on axle stands, then
support the rear suspension crossmember
with a jack. Remove the roadwheels and
unscrew the rear suspension strut top
mounting bolts (two per side - see Chapter
10).
14Use white paint or similar (do not use a
sharp-pointed scriber, which might break the
underbody protective coating and cause
rusting) to mark the exact relationship of the
crossmember to the underbody. Unscrew the
four mounting bolts (see illustration). Lower
the crossmember approximately 3 inches (75
mm) on the jack, and support it securely.
Warning: DO NOT place any part
of your body under the vehicle
when it is supported only by a
jack!
5 EVAPorative emissions control
(EVAP) system -
general information, checking
and component renewal
6•14 Emissions control systems
4.64 . . . slotted socket will be required to
tighten sensor with a torque wrench5.10 Charcoal canister-purge solenoid
valve (arrowed) is clipped to bulkhead
behind engine5.14 Support rear suspension
crossmember on jack, and remove
mounting bolts (arrowed) . . .
5.15 . . . lower crossmember by 3 inches,
and unscrew charcoal canister assembly
rear retaining bolts (arrowed) . . .5.16 . . . unplug hoses (arrowed) from
canister assembly . . .
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15Unscrew the two rearmost canister
assembly retaining bolts (see illustration).
16Unplug the two hoses from the canister
assembly, noting which way round they are
fitted (see illustration).
17Unscrew the canister assembly’s front
retaining bolt (see illustration). Withdraw the
canister assembly.
18Release the clip, and drive out the pin to
separate the canister from its bracket (see
illustration).
19On reassembly, refit the canister to its
bracket and refit the assembly to the vehicle,
tightening the retaining bolts securely, and
ensuring that the two hoses are securely
reconnected to their original unions.
20Offer up the crossmember and refit the
crossmember bolts, tightening them only
lightly at this stage.
21The crossmember must now be aligned
on the underbody. Ford specify the use of
service tool 15-097, which is a pair of tapered
guides, with attachments to hold them in the
crossmember as it is refitted (see
illustration). However, since the working
diameter of these tools is 20.4 mm, and since
the corresponding aligning holes in the
crossmember and underbody are 21 mm and
22 mm in diameter, there is a significant in-
built tolerance possible in the crossmember’s
alignment, even if the correct tools are used. If
these tools are not available, align the
crossmember by eye, centring thecrossmember aligning holes on those of the
underbody, and using the marks made on
removal for assistance. Alternatively, use a
tapered drift such as a clutch-aligning tool, or
a deep socket spanner of suitable size.
22Once the crossmember is aligned as
precisely as possible, tighten its bolts to the
specified torque (see Chapter 10
Specifications) without disturbing its position
(see illustration). Recheck the alignment
once all the bolts are securely tightened.
23The remainder of the refitting procedure is
the reverse of removal.
24Remember that, since the rear suspension
crossmember has been disturbed, the wheel
alignment and steering angles must be
checked fully and carefully as soon as
possible, with any necessary adjustments
being made. This operation is best carried out
by an experienced mechanic using proper
checking equipment; the vehicle should
therefore be taken to a Ford dealer or similar
for attention.
Charcoal canister - Estate models
25Disconnect the battery negative (earth)
lead - see Section 1 of Chapter 5.
26Raise the rear of the vehicle, and support
it securely on axle stands.
Warning: DO NOT place any part
of your body under the vehicle
when it is supported only by a
jack!27Disconnect the two hoses from the
canister assembly, noting which way round
they are fitted.
28Unscrew the canister assembly retaining
bolt and withdraw the assembly, unclipping it
from the front mounting.
29Remove the plastic cover, and drive out
the pin to separate the canister from its
bracket (see illustration).
30On refitting, secure the canister to its
bracket, and refit the assembly to the vehicle.
Tighten the retaining bolt securely, and ensure
that the two hoses are securely reconnected
to their original unions.
General information
1To reduce oxides of nitrogen (NOx)
emissions, some of the exhaust gases are
recirculated through the EGR valve to the inlet
manifold. This has the effect of lowering
combustion temperatures.
2The system consists of the EGR valve, the
EGR exhaust gas pressure differential sensor,
the EGR solenoid valve, the ECU, and various
sensors - see illustration 2.1A. The ECU is
programmed to produce the ideal EGR valve
lift for each operating condition.
Checking
EGR valve
3Start the engine and allow it to idle.
4Detach the vacuum hose from the EGR
valve, and attach a hand vacuum pump in its
place.
5Apply vacuum to the EGR valve. Vacuum
should remain steady, and the engine should
run poorly.
(a) If the vacuum doesn’t remain steady and
the engine doesn’t run poorly, renew the
EGR valve and recheck it.
(b) If the vacuum remains steady but the
engine doesn’t run poorly, remove the
6 Exhaust Gas Recirculation
(EGR) system-
general information, checking
and component renewal
Emissions control systems 6•15
6
5.22 . . . ensure aligned crossmember
does not move - Ford tools used here -
while mounting bolts are tightened5.29 Charcoal canister assembly - Estate
models - showing plastic cover (arrowed)
and pin securing canister to mounting
bracket
5.17 . . . and remove front retaining bolt
(arrowed) to release canister assembly -
Saloon and Hatchback models5.18 Release clip and drive out pin to
separate canister from mounting bracket5.21 Refitting rear suspension crossmember
with Ford service tools (arrowed) in place to
align it with underbody . . .
procarmanuals.com

EGR valve, and check the valve and the
inlet manifold for blockage. Clean or
renew parts as necessary, and recheck.
EGR system
6Any further checking of the system requires
special tools and test equipment. Take the
vehicle to a dealer service department for
checking.
Component renewal
Note:These components will be very hot
when the engine is running. Always allow the
engine to cool down fully before starting work,
to prevent the possibility of burns.
EGR valve
7Disconnect the battery negative (earth) lead
- see Section 1 of Chapter 5.
8Remove the air mass meter and resonator -
refer to Chapter 4.
9Detach the vacuum hose, unscrew the
sleeve nut securing the EGR pipe to the valve,
remove the two valve mounting bolts, and
withdraw the valve from the inlet manifold
(see illustrations). Ensure that the end of the
pipe is not damaged or distorted as the valve
is withdrawn, and note the valve’s gasket; this
must be renewed whenever the valve is
disturbed.
10Note that the metal pipe from the valve to
the manifold itself should not be disturbed - it
is not available separately from the manifold.However, check whenever the manifold is
removed that the pipe’s end fitting is securely
fastened (see illustration).
11Check the valve for sticking and heavy
carbon deposits. If such is found, clean the
valve or renew it.
12Refitting is the reverse of the removal
procedure. Apply a smear of anti-seize
compound to the sleeve nut threads, fit a new
gasket, and tighten the valve bolts to the
specified torque wrench setting.
EGR pipe
13Disconnect the battery negative (earth)
lead - see Section 1 of Chapter 5.
14Remove the air mass meter and resonator
- refer to Chapter 4.
15Unbolt the exhaust manifold heat shield
and remove both parts, or move them aside
as required to reach the end of the EGR pipe.
Unscrew the sleeve nut securing the pipe to
the exhaust manifold (see illustration).
16Undo the two screws securing the pipe to
the ignition coil bracket, then disconnect the
two vacuum hoses - note that these are of
different sizes, to ensure that they cannot be
mixed up on reconnection. Unscrew the
sleeve nut securing the EGR pipe to the valve
(see illustration). Withdraw the pipe.
17Check the condition of both hoses, and
renew them if necessary (see Chapter 1). Note
that if the exhaust gases have been backfiring
excessively - eg, due to a blocked exhaust
system - both hoses must be renewed, andtheir connections on the pipe must be cleaned
thoroughly.
18Refitting is the reverse of the removal
procedure; ensure that the hoses are securely
connected to the correct unions. Apply a
smear of anti-seize compound to the sleeve
nut threads, tighten the nuts securely, and
tighten the two screws to their specified
torque wrench setting.
EGR exhaust gas pressure differential
sensor
19Refer to Section 4 of this Chapter.
EGR solenoid valve
Note:This component can be identified by its
larger top and its two fastening screws. Do not
confuse it with the adjacent pulse-air solenoid
valve, especially when reconnecting vacuum
hoses.
20Disconnect the battery negative (earth)
lead - see Section 1 of Chapter 5.
21Remove the air mass meter and resonator
- refer to Chapter 4. If better access is
required, remove the plenum chamber also
(see illustration).
22Releasing its wire clip, unplug the
electrical connector from the valve. Remove
the two retaining screws, and withdraw the
valve from the bulkhead mounting bracket,
then label and disconnect the two vacuum
hoses.
23Refitting is the reverse of the removal
procedure; ensure that the hoses are correctly
reconnected.
6•16 Emissions control systems
6.9A Disconnecting vacuum hose from
Exhaust Gas Recirculation (EGR) valve . . .6.9B . . . unscrew EGR pipe sleeve nut and
remove bolts (arrowed) to release valve
from inlet manifold6.10 Check end fitting of EGR pipe into
inlet manifold whenever manifold is
removed, but do not disturb
6.15 Unbolt exhaust manifold heat shield,
and unscrew sleeve nut (arrowed) securing
EGR pipe to exhaust manifold . . .6.16 . . . undo screws “A” and sleeve
nut “B”, then disconnect hoses “C” - note
different sizes - to release EGR pipe6.21 EGR solenoid valve “A” and EGR
exhaust gas pressure differential sensor
“B”, located on bulkhead mounting bracket
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