FORD MONDEO 1993 Service Repair Manual

and remove the clevis pin securing the servo
unit pushrod to the pedal cross-link arm.
7On left-hand drive models, unscrew the nut
securing the pedal trunnion to the servo unit
pushrod inside the passenger compartment.
The nut is located near the top of the pedal,
and is accessible through an access hole. For
improved access, remove the lower facia
panel first.
8Withdraw the servo unit from the bulkhead,
and remove it from the engine compartment.
On left-hand drive models, take care not to
damage the bulkhead rubber grommet as the
pushrod passes through it.
9Note that the servo unit cannot be
dismantled for repair or overhaul and, if faulty,
must be renewed.
Refitting
10Refitting is a reversal of the removal
procedure. Refer to Section 11 for details of
refitting the master cylinder.
Removal
1Depress the brake pedal four or five times,
to dissipate any remaining vacuum from the
servo unit.
2Disconnect the vacuum hose adaptor at the
servo unit, by pulling it free from the rubber
grommet (see illustration). If it is reluctant to
move, prise it free, using a screwdriver with its
blade inserted under the flange.
3Detach the vacuum hose from the inlet
manifold connection, pressing in the collar to
disengage the tabs, then withdrawing the
collar slowly.
4If the hose or the fixings are damaged or in
poor condition, they must be renewed.
Testing
5Examine the non-return valve for damage
and signs of deterioration, and renew it if
necessary. The valve may be tested by
blowing through its connecting hoses in both
directions. It should only be possible to blow
from the servo end towards the inlet manifold.
Refitting
6Refitting is a reversal of the removal
procedure. If fitting a new non-return valve,
ensure that it is fitted the correct way round.
Removal
1On non-ABS models, the two pressure-
control relief valves (sometimes referred to as
pressure-conscious reducing valves) are
located on the master cylinder outlets to the
rear brake line circuits.
2Unscrew and remove the fluid reservoir filler
cap, and draw off the fluid - see Section 11.
3Position some rags beneath the master
cylinder, to catch any spilled fluid.
4Clean around the valve to be removed.
Hold the PCR valve stationary with one
spanner, and unscrew the hydraulic pipe
union nut with another spanner. Pull out the
pipe, and bend it slightly away from the valve.
5Unscrew the PCR valve from the master
cylinder.
6Note that the primary and secondary PCR
valves have different thread diameters, to
prevent incorrect fitment. The primary valve
has a 12 mm diameter thread, and the
secondary valve has a 10 mm diameter thread
(see illustration).
Refitting
7Refitting is a reversal of the removal
procedure. On completion, bleed the
hydraulic system as described in Section 15.
Removal
1On ABS models, the pressure-control relief
valves are located on the ABS hydraulic unit
(see illustration).
2Disconnect the battery negative (earth) lead
(Chapter 5, Section 1).
3Remove the air cleaner assembly as
described in Chapter 4.
4Remove the engine air inlet duct and air
plenum chamber.
5Disconnect the low fluid level warning
multi-plug from the brake fluid reservoir.
6Unscrew and remove the brake fluid
reservoir filler cap, and completely seal the
top of the reservoir using cling film or
adhesive tape. This will reduce loss of fluid
when the PCR valve is removed.
7Unscrew the master cylinder mounting
nuts, and carefully withdraw the cylinder from
the servo unit, leaving the brake pipes still
connected to it. Move the master cylinder
over to the left-hand side of the enginecompartment, to rest against the left-hand
suspension turret. (Throughout this manual,
left- and right-hand are as seen from the
driver’s seat.)
8Unscrew the servo unit mounting nuts, and
move the unit to one side.
9Position some rags beneath the ABS unit,
to catch spilled fluid.
10Clean around the valve to be removed.
Hold the PCR valve stationary with one
spanner, and unscrew the hydraulic pipe
union nut with another spanner. Pull out the
pipe, and bend it slightly away from the valve.
11Unscrew the PCR valve from the ABS
unit.
Refitting
12Refitting is a reversal of the removal
procedure. On completion, bleed the
hydraulic system as described in Section 15.
19 Pressure-control relief valve
(ABS models) -
removal and refitting
18 Pressure-control relief valve
(non-ABS models) -
removal and refitting
17 Vacuum servo unit vacuum
hose and non-return valve -
removal, testing and refitting
Braking system 9•13
9
17.2 Removing the plastic adaptor from
the servo unit
18.6 Pressure-control relief valve
locations
1 Primary PCR valve (12 mm)
2 Secondary PCR valve (10 mm)
19.1 Pressure-control relief valve locations
on the ABS hydraulic unit
1 PCR valve, rear right brake circuit
2 Outlet, front left brake circuit
3 Inlet, from brake master cylinder secondary
circuit
4 PCR valve, rear left brake circuit
5 Outlet, front right brake circuit
6 Inlet, from brake master cylinder primary
circuit
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Note:If any part of the ABS hydraulic unit is
defective, it must be renewed as an assembly.
Apart from the relay box (Section 22),
individual spare parts are not available.
Removal
1Remove both pressure-control relief valves
as described in Section 19.
2Identify the location of the remaining brake
hydraulic pipes on the ABS hydraulic unit,
then unscrew the union nuts and pull out the
pipes. Carefully bend the pipes away from the
hydraulic unit, to allow the unit to be removed.
3Disconnect the multi-plugs from the
hydraulic unit. To disconnect the main 22-pin
multi-plug, push the locktab, then swivel the
multi-plug outwards and unhook it.
Right-hand drive models
4Have an assistant hold the brake pedal
depressed, then extract the spring clip and
remove the clevis pin securing the servo unit
pushrod to the pedal cross-link arm.
5Remove the vacuum servo unit from the
engine compartment.
Left-hand drive models
6Unscrew the nut securing the pedal
trunnion to the servo unit pushrod inside the
passenger compartment. The nut is located
near the top of the pedal, and is accessible
through an access hole. For improved access,
remove the lower facia panel first.
7Remove the vacuum servo unit, together
with the pushrod, from the engine
compartment. Take care not to damage the
rubber grommet in the bulkhead.
All models
8Unscrew the pump mounting nut.
9Raise the left-hand side of the ABS
hydraulic unit, then swivel the unit out of the
right-hand mounting. Take care not to lose the
bracket studs and insulator ring.
Refitting
10Locate the insulator ring on the pump
end, and fit the stud cap to the insulator ring.
11Lower the ABS hydraulic unit into
position, right-hand end first.
12Fit the right-hand bracket studs onto the
insulators.
13Lower the left-hand end of the ABS
hydraulic unit onto the bracket, then fit and
tighten the pump mounting nut.
Left-hand drive models
14Locate the vacuum servo unit and
pushrod on the bulkhead bracket, taking care
not to damage the rubber grommet.
15Insert the pushrod in the pedal trunnion,
and tighten the nut.
16Refit the lower facia panel if it was
removed.
Right-hand drive models
17Locate the vacuum servo unit and
pushrod on the bulkhead bracket.
18Refit the clevis pin and spring clip
securing the servo unit pushrod to the pedal
cross-link arm.
All models
19Reconnect the multi-plugs to the
hydraulic unit.
20Reconnect the brake pipes to the
hydraulic unit, and tighten the union nuts.
21Refit both pressure-control relief valves,
with reference to Section 20.
Testing
1Checking of the sensors is done before
removal, connecting a voltmeter to the
disconnected sensor multi-plug. Using an
analogue (moving coil) meter is not practical,
since the meter does not respond quickly
enough. A digital meter having an AC facility
may be used to check that the sensor is
operating correctly. To do this, raise the
relevant wheel then disconnect the wiring to
the ABS sensor and connect the meter to it.
Spin the wheel and check that the output
voltage is between 1.5 and 2.0 volts,
depending on how fast the wheel is spun.
Alternatively, an oscilloscope may be used to
check the output of the sensor - an alternating
current will be traced on the screen, of
magnitude depending on the speed of the
rotating wheel.
2If the sensor output is low or zero, renew
the sensor.
Removal
Front wheel sensor
3Apply the handbrake, jack up the front of
the vehicle and support it on axle stands.
Remove the relevant wheel.
4Unscrew the sensor mounting bolt located
on the steering knuckle, and withdraw the
sensor (see illustrations).
5Remove the sensor wiring loom from thesupport brackets on the front suspension
strut and wheel arch.
6Prise out the stud clips, and remove the
Torx screws and screw clips holding the wheel
arch liner in position. Withdraw the liner.
7Disconnect the multi-plug, and withdraw
the sensor and wiring loom.
Rear wheel sensor
8Chock the front wheels, and engage 1st
gear (or “P”). Jack up the rear of the vehicle
and support it on axle stands. Remove the
relevant wheel.
9Unscrew the sensor mounting bolt, located
on the brake backplate (drum brakes) or rear
suspension knuckle (disc brakes), and
withdraw the sensor.
10On disc brake models, prise out the stud
clips, and remove the Torx screws and screw
clips holding the wheel arch liner in position.
Withdraw the liner.
11Disconnect the sensor wiring loom from
the supports on the rear suspension strut (or
knuckle) and wheel arch.
12Working inside the vehicle, lift the rear
seat cushion, then disconnect the multi-plug
for the sensor wiring loom (see illustration).
13Withdraw the sensor and wiring loom
through the rubber grommet in the rear floor.
Refitting
Front and rear wheel sensors
14Refitting is a reversal of the removal
procedure.
Removal
1Disconnect the battery negative (earth) lead
(Chapter 5, Section 1).
2Detach the vacuum hose from the inlet
manifold connection, pressing in the collar to
disengage the tabs, then withdrawing the
collar slowly.
3To improve access, free the heater hose
from its retaining clips, and position it clear of
the relay box.
4Disconect the wiring connector(s) from the
relay box and, where necessary, the speed
sender unit.
22 ABS relay box -
removal and refitting
21 ABS wheel sensor -
testing, removal and refitting
20 ABS hydraulic unit -
removal and refitting
9•14 Braking system
21.4 Unscrew the mounting bolt and
remove the ABS sensor21.12 Rear ABS sensor wiring multi-plug
located beneath the rear seat
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5Slacken and remove the four Torx retaining
screws, and withdraw the relay box from the
hydraulic unit (see illustration).
Refitting
6Refitting is a reversal of the removal
procedure. Do not overtighten the relay box
retaining screws, as the plastic is easily
cracked
Removal
1Disconnect the battery negative (earth) lead
(Chapter 5, Section 1).
2Using a small screwdriver and a suitable
pad (to protect the facia), prise out the TCS
inhibitor switch from the facia.3Disconnect the multi-plug from the switch,
and withdraw the switch.
Refitting
4Refitting is a reversal of the removal
procedure.
Removal
1The TCS throttle actuator is located in the
front right-hand corner of the engine
compartment. First disconnect the battery
negative (earth) lead (Chapter 5, Section 1).
2Disconnect the wiring multi-plug at the TCS
actuator (see illustration).
3Prise off the motor cover (see illustration).4Turn the upper throttle control segment, to
provide some play in the accelerator cable
leading to the throttle housing, then
disconnect the cable by unhooking the end
stop. Release the cable from the motor
housing support (see illustrations).
5Turn the lower accelerator control segment,
to provide play in the accelerator cable from
the accelerator pedal, then disconnect the
cable by unhooking the end stop. Release the
cable from the motor housing support (see
illustration).
6Unscrew the mounting bolts, and lift out the
TCS throttle actuator (see illustration).
Refitting
7Refitting is a reversal of the removal
procedure. Adjust the accelerator cables as
described in Chapter 4.
Removal
1Disconnect the battery negative (earth) lead
(Chapter 5, Section 1).
2Remove the lower facia panel, with
reference to Chapter 11.
3Disconnect the wiring multi-plug from the
switch.
4Rotate the switch anti-clockwise by a
quarter-turn, and withdraw it from the pedal
bracket (see illustration).
25 Stop-light switch -
removal and refitting
24 TCS throttle actuator -
removal and refitting
23 TCS inhibitor switch -
removal and refitting
Braking system 9•15
9
24.4B Releasing the cable from the motor
housing support24.4A Disconnecting the accelerator cable
(arrowed) from the upper throttle control
segment
24.5 Disconnecting the accelerator cable
(arrowed) from the lower throttle control
segment24.6 Removing the TCS actuator
22.5 Removing the ABS relay box24.2 Disconnecting the multi-plug
(arrowed) at the TCS actuator24.3 Removing the TCS motor cover
25.4 Removing the stop-light switch
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Refitting and adjustment
5With the switch removed, reset it by fully
extending its plunger.
6Depress the brake pedal until the distance
between the pedal and mounting bracket is as
shown (see illustration).
7Hold the pedal in this position, and refit the
stop-light switch to the mounting bracket .
8With the switch securely clipped in position,
release the brake pedal, and gently pull it fully
back to the at-rest position. This will
automatically set the adjustment of the stop-
light switch.
9reconnect the wiring connector and the
battery, and check the operation of the switch
prior to refitting the lower facia panel (Chapter 11).
Removal
1Raise the front and rear of the vehicle, and
support it on axle stands. Fully release the
handbrake lever.
2Remove the centre console as described in
Chapter 11.
3Working beneath the vehicle, release the
exhaust system from the rubber mountings.
Lower the exhaust system as far as possible,
supporting it on blocks or more axle stands.
4Detach the exhaust heat shield from the
underbody.
5Unhook the secondary (rear) handbrake
cables from the equaliser bar.
6Working inside the vehicle, unscrew and
remove the two mounting bolts securing the
handbrake lever to the floor (see illustration).7Turn the handbrake lever upsidedown, then
disconnect the primary cable end from the
segment.
8Withdraw the handbrake from inside the
vehicle.
Refitting
9Refitting is a reversal of the removal
procedure, making sure that the primary cable
is correctly located in the segment. Check the
operation of the handbrake before returning
the vehicle to normal service.
Removal
Primary (front)
1Remove the handbrake lever as described
in Section 26.
2Prise the grommet from the underbody,
and withdraw the cable from beneath the
vehicle.
Secondary (rear)
3Chock the front wheels, and engage 1st
gear (or “P”). Jack up the rear of the vehicle
and support it on axle stands. Fully release
the handbrake lever.
4Remove the relevant rear wheel.5Working beneath the vehicle, release the
exhaust system from the rubber mountings.
Lower the exhaust system as far as possible,
supporting it on blocks or more axle stands.
6Unbolt the exhaust heat shield from the
underbody.
7Unhook the relevant cable from the
equaliser bar.
8On drum brake models, remove the rear
brake shoes on the relevant side as described
in Section 6, then remove the outer cable from
the backplate by compressing the three
retaining lugs (use a suitable ring spanner)
and pushing the cable through (see
illustration).
9On disc brake models, unhook the end of
the cable from the handbrake operating arm
on the rear caliper.
10Release the lugs securing the outer cable
to the underbody brackets, then release the
cable from the clips, and withdraw it from
under the vehicle (see illustrations).
Refitting
All cables
11Refitting is a reversal of the removal
procedure, but make sure that the cable end
fittings are correctly located. Check the
operation of the handbrake before returning
the vehicle to normal service.
27 Handbrake cables -
removal and refitting
26 Handbrake lever -
removal and refitting
9•16 Braking system
25.6 To ensure correct adjustment,
position the brake pedal as shown prior to
refitting the switch to its mounting bracket
26.6 Handbrake lever mounting bolts27.8 Using a ring spanner to compress the
retaining lugs securing the outer cable to
the backplate
27.10A Release the lugs using a ring
spanner . . .27.10B . . . and remove the outer cable
from the underbody brackets
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Chapter 6 Emissions control systems
Catalytic converter - general information, checking
and component renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Diagnosis system - general information . . . . . . . . . . . . . . . . . . . . . . 3
Electronic control system - description and precautions . . . . . . . . . 2
Engine compartment wiring check . . . . . . . . . . . . . . . See Chapter 1
EVAPorative emissions control (EVAP) system - general
information, checking and component renewal . . . . . . . . . . . . . . 5
Exhaust Gas Recirculation (EGR) system - general
information, checking and component renewal . . . . . . . . . . . . . . 6
Exhaust system check . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Information sensors - general information, testing,
removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Positive Crankcase Ventilation (PCV) system - general
information, checking and component renewal . . . . . . . . . . . . . . 8
Positive Crankcase Ventilation (PCV) system check
and filter cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Pulse-air system - general information, checking
and component renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Underbonnet hose check . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Crankshaft speed/position sensor
Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 to 450 ohms
Camshaft position sensor
Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 to 900 ohms
Intake air temperature sensor
Resistance:
At -40°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 860 to 900 k ohms
At 20°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 to 40 k ohms
At 100°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 to 2.5 k ohms
At 120°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 to 1.3 k ohms
Throttle potentiometer
Resistance - see text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 to 6000 ohms
Power steering pressure switch
Operating pressure - green switch body:
Contacts open - infinite resistance . . . . . . . . . . . . . . . . . . . . . . . . . . 31.5 ± 3.5 bars
Contacts close - 0 to 2.5 ohms resistance . . . . . . . . . . . . . . . . . . . . Between 13.5 and 24.0 bars
Charcoal canister-purge solenoid valve
Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 to 120 ohms
Pulse-air solenoid valve
Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 to 120 ohms
Torque wrench settingsNm lbf ft
Camshaft position sensor screw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 to 23 13 to 17
Intake air temperature sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 17
Oxygen sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 44
Exhaust Gas Recirculation (EGR) system components:
Valve-to-inlet manifold bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6
Pipe-to-ignition coil screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7
Pulse-air system components:
Filter housing mounting bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 35
Piping-to-exhaust manifold sleeve nuts . . . . . . . . . . . . . . . . . . . . . . . 32 24
6•1
Easy,suitable for
novice with little
experienceFairly easy,suitable
for beginner with
some experienceFairly difficult,suitable
for competent DIY
mechanicDifficult,suitable for
experienced DIY
mechanicVery difficult,
suitable for expert DIY
or professional
Degrees of difficulty
Specifications Contents
6
procarmanuals.com

To minimise pollution of the atmosphere
from incompletely-burned and evaporating
gases, and to maintain good driveability and
fuel economy, a number of emission control
systems are used on these vehicles. They
include the following:
(a) The engine management system
(comprising both fuel and ignition sub-
systems) itself.
(b) Positive Crankcase Ventilation (PCV)
system.
(c) Evaporative Emissions Control (EVAP)
system.
(d) Exhaust Gas Recirculation (EGR) system.
(e) Catalytic converter.
The Sections of this Chapter include
general descriptions, checking procedures
within the scope of the home mechanic, and
component renewal procedures (when
possible) for each of the systems listed above.
Before assuming an emissions control system
is malfunctioning, check the fuel and ignition
systems carefully (see Chapters 4 and 5). The
diagnosis of some emission control devices
requires specialised tools, equipment and
training. If checking and servicing become too
difficult, or if a procedure is beyond the scope ofyour skills, consult your dealer service
department or other specialist.
This doesn’t mean, however, that emission
control systems are particularly difficult to
maintain and repair. You can quickly and
easily perform many checks, and do most of
the regular maintenance, at home with
common tune-up and hand tools. Note:The
most frequent cause of emissions problems is
simply a loose or broken electrical connector
or vacuum hose, so always check the
electrical connectors and vacuum hoses first.
Pay close attention to any special
precautions outlined in this Chapter. It should
be noted that the illustrations of the various
systems may not exactly match the system
installed on your vehicle, due to changes
made by the manufacturer during production
or from year-to-year.
Vehicles sold in some areas will carry a
Vehicle Emissions Control Information (VECI)
label, and a vacuum hose diagram located in
the engine compartment. These contain
important specifications and setting
procedures for the various emissions control
systems, with the vacuum hose diagram
identifying emissions control components.
When servicing the engine or emissions
systems, the VECI label in your particular
vehicle should always be checked for up-to-
date information.Description
The EEC-IV (Ford’s fourth-generation
Electronic Engine Control system) engine
management system controls fuel injection by
means of a microcomputer known as the ECU
(Electronic Control Unit) (see illustrations).
The ECU receives signals from various
sensors, which monitor changing engine
operating conditions such as intake air mass
(ie, intake air volume and temperature),
coolant temperature, engine speed,
acceleration/deceleration, exhaust oxygen
content, etc. These signals are used by the
ECU to determine the correct injection
duration.
The system is analogous to the central
nervous system in the human body - the
sensors (nerve endings) constantly relay
signals to the ECU (brain), which processes
the data and, if necessary, sends out a
command to change the operating
parameters of the engine (body) by means of
the actuators (muscles).
Here’s a specific example of how one
portion of this system operates. An oxygen
sensor, located in the exhaust downpipe,
2 Electronic control system -
description and precautions1 General information
6•2 Emissions control systems
procarmanuals.com

Emissions control systems 6•3
6
2.1B Location of principal fuel injection, ignition and
emissions control system components 2.1A Engine management system, showing fuel injection,
ignition and emissions control sub-systems
1 ECU (Electronic Control Unit)
2 Fuel pump/fuel gauge sender
unit
3 Fuel pump relay
4 Fuel filter
5 Idle speed control valve
6 Air mass meter
7 Air cleaner assembly
8 Fuel pressure regulator
9 Fuel rail
10 Throttle potentiometer
11 Intake air temperature sensor
12 Fuel injector
13 Camshaft position sensor
14 Charcoal canister
15 Charcoal canister-purge
solenoid valve
16 Ignition coil
17 Battery
18 Ignition module - only
separate (from ECU) on
vehicles with automatic
transmission
19 Coolant temperature sensor
20 Oxygen sensor
21 Crankshaft speed/position
sensor
22 Power supply relay
23 Power steering pressure
switch24 Air conditioning compressor
clutch solenoid
25 Service connector - for octane
adjustment
26 Self-test connector - for Ford
STAR tester diagnostic
equipment
27 Diagnosis connector - for Ford
diagnostic equipment FDS
2000
28 Ignition switch
29 Fuel cut-off switch
30 Exhaust Gas Recirculation
(EGR) solenoid valve
31 Exhaust Gas Recirculation
(EGR) valve
32 Exhaust Gas Recirculation
(EGR) exhaust gas pressure
differential sensor
33 Exhaust Gas Recirculation
(EGR) pressure differential
measuring point
34 To inlet manifold
35 Pulse-air filter housing
36 Pulse-air solenoid valve
37 Air conditioning/radiator
electric cooling fan control
38 Automatic transmission
control system - where
applicable1 ECU (Electronic Control Unit)
2 Self-test, diagnosis and service connectors
(left to right)
3 Bulkhead component mounting bracket - manual
transmission - showing from left to right, (EGR) solenoid
valve, pulse-air solenoid valve and (EGR) exhaust gas
pressure differential sensor
4 Bulkhead component mounting bracket - automatic
transmission - showing from left to right, (EGR) solenoid
valve, pulse-air solenoid valve and (EGR) exhaust gas
pressure differential sensor, with separate ignition module
above
5 Throttle housing, including potentiometer
6 Idle speed control valve
7 Intake air temperature sensor
8 Air mass meter
9 Exhaust Gas Recirculation (EGR) valve
10 Coolant temperature sensor
11 Crankshaft speed/position sensor
12 Pulse-air filter housing
13 Oxygen sensor
14 Ignition coil and spark plug (HT) leads
15 Camshaft position sensor
16 Fuel injector(s)
17 Power steering pressure switch
18 Air cleaner assembly
19 Air intake tube and resonators - under left-hand front wing
20 Resonator
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
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coolant or EGR pipes, etc. In almost all cases,
damage of this sort is caused in the first
instance by incorrect routing on reassembly
after previous work has been carried out (see
the note at the beginning of this sub-Section).
6Obviously wires can break or short together
inside the insulation so that no visible
evidence betrays the fault, but this usually
only occurs where the wiring loom has been
incorrectly routed so that it is stretched taut or
kinked sharply; either of these conditions
should be obvious on even a casual
inspection. If this is thought to have happened
and the fault proves elusive, the suspect
section of wiring should be checked very
carefully during the more detailed checks
which follow.
7Depending on the extent of the problem,
damaged wiring may be repaired by rejoining
the break or splicing-in a new length of wire,
using solder to ensure a good connection,
and remaking the insulation with adhesive
insulating tape or heat-shrink tubing, as
desired. If the damage is extensive, given the
implications for the vehicle’s future reliability,
the best long-term answer may well be to
renew that entire section of the loom, however
expensive this may appear.
8When the actual damage has been
repaired, ensure that the wiring loom is
rerouted correctly, so that it is clear of other
components, is not stretched or kinked, and is
secured out of harm’s way using the plastic
clips, guides and ties provided.
9Check all electrical connectors, ensuring
that they are clean, securely fastened, and
that each is locked by its plastic tabs or wire
clip, as appropriate. If any connector shows
external signs of corrosion (accumulations of
white or green deposits, or streaks of “rust”),
or if any is thought to be dirty, it must be
unplugged and cleaned using electrical
contact cleaner. If the connector pins are
severely corroded, the connector must be
renewed; note that this may mean the renewalof that entire section of the loom - see your
local Ford dealer for details.
10If the cleaner completely removes the
corrosion to leave the connector in a
satisfactory condition, it would be wise to
pack the connector with a suitable material
which will exclude dirt and moisture, and
prevent the corrosion from occurring again; a
Ford dealer may be able to recommend a
suitable product. Note:The system’s
connectors use gold-plated pins, which must
notbe mixed with the older tin-plated types
(readily identifiable from the different colour) if
a component is renewed, nor must the lithium
grease previously used to protect tin-plated
pins be used on gold-plated connectors.
11Following the accompanying schematic
diagram, and working methodically around
the engine compartment, check carefully that
all vacuum hoses and pipes are securely
fastened and correctly routed, with no signsof cracks, splits or deterioration to cause air
leaks, or of hoses that are trapped, kinked, or
bent sharply enough to restrict air flow (see
illustrations). Check with particular care at all
connections and sharp bends, and renew any
damaged or deformed lengths of hose.
12Working from the fuel tank, via the filter, to
the fuel rail (and including the feed and return),
check the fuel lines, and renew any that are
found to be leaking, trapped or kinked.
13Check that the accelerator cable is
correctly secured and adjusted; renew the
cable if there is any doubt about its condition,
or if it appears to be stiff or jerky in operation.
Refer to the relevant Sections of Chapter 4 for
further information, if required.
14If there is any doubt about the operation
of the throttle, remove the plenum chamber
from the throttle housing, and check that the
throttle valve moves smoothly and easily from
the fully-closed to the fully-open position and
Emissions control systems 6•5
6
3.11A Vacuum hose routing schematic diagram
A Exhaust Gas Recirculation (EGR) solenoid valve
B Pulse-air solenoid valve
C Exhaust Gas Recirculation (EGR) exhaust gas pressure
differential sensor
D Exhaust Gas Recirculation (EGR) valve
E Charcoal canister-purge solenoid valve
F Restrictor
G Idle-increase solenoid valve - where fitted
H Connection to plenum chamber
J Connection to inlet manifold
K Fuel pressure regulator
L Connection to Positive Crankcase Ventilation (PCV) valve
M Pulse-air filter housing
N Connection to heating/air conditioning system controls
P Charcoal canister
3.11B Installation of vacuum hoses in engine compartment
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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
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