1993 FORD MONDEO battery

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
procarmanuals.com

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
procarmanuals.com

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
procarmanuals.com

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
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
procarmanuals.com

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

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
6
procarmanuals.com