1993 FORD MONDEO relay

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
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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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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
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Chapter 12 Body electrical system
Air bag clock spring - removal and refitting . . . . . . . . . . . . . . . . . . . 30
Air bag control module - removal and refitting . . . . . . . . . . . . . . . . . 29
Air bag unit (driver’s side) - removal and refitting . . . . . . . . . . . . . . . 28
Anti-theft alarm system - general information . . . . . . . . . . . . . . . . . . 20
Auxiliary warning system - general information and
component renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Battery - check, maintenance and charging . . . . . . . . See Chapter 1
Battery - removal and refitting . . . . . . . . . . . . . . . . . . . See Chapter 5
Bulbs (exterior lights) - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Bulbs (interior lights) - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Clock - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Compact disc player - removal and refitting . . . . . . . . . . . . . . . . . . . 25
Cruise control system - general information . . . . . . . . . . . . . . . . . . . 21
Electrical fault finding - general information . . . . . . . . . . . . . . . . . . . 2
Electrical system check . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Exterior light units - removal and refitting . . . . . . . . . . . . . . . . . . . . . 7
Fuses, relays and timer module - testing and renewal . . . . . . . . . . . 3
General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Headlight beam alignment - checking and adjustment . . . . . . . . . . 8
Headlight levelling motor - removal and refitting . . . . . . . . . . . . . . . 9Horn - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Instrument panel - removal and refitting . . . . . . . . . . . . . . . . . . . . . . 10
Instrument panel components - removal and refitting . . . . . . . . . . . 11
Radio aerial - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Radio/cassette player - coding, removal and refitting . . . . . . . . . . . 23
Radio/cassette player power amplifier - removal and refitting . . . . . 24
Speakers - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Speedometer drive cable - removal and refitting . . . . . . . . . . . . . . . 12
Stop-light switch - removal and refitting . . . . . . . . . . . See Chapter 9
Switches - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Tailgate wiper motor assembly - removal and refitting . . . . . . . . . . . 17
TCS inhibition switch - removal and refitting . . . . . . . . See Chapter 9
Trip computer module - removal and refitting . . . . . . . . . . . . . . . . . 18
Windscreen/tailgate washer system and wiper blade
check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Windscreen/tailgate washer system components - removal
and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Windscreen wiper motor and linkage - removal and refitting . . . . . . 16
Wiper arms - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Fuses (auxiliary fusebox in engine compartment)
Note:Fuse ratings and circuits are liable to change from year to year. Consult the handbook supplied with the vehicle, or consult a Ford dealer,
for specific information.
Fuse No Rating Colour Circuit(s) protected
1 80 Black . . . . . . . . . . . . . . . . . . . . . . . . . . Power supply to main fusebox
2 60 Yellow . . . . . . . . . . . . . . . . . . . . . . . . . Radiator electric cooling fans
3 60 Yellow . . . . . . . . . . . . . . . . . . . . . . . . . Diesel engine glow plugs and/or ABS braking system
4 20 Yellow . . . . . . . . . . . . . . . . . . . . . . . . . Ignition system, or ignition and daytime running lights
5 30 Light green . . . . . . . . . . . . . . . . . . . . . . Heated windscreen (left-hand side)
6 30 Light green . . . . . . . . . . . . . . . . . . . . . . Heated windscreen (right-hand side)
7 30 Light green . . . . . . . . . . . . . . . . . . . . . . ABS braking system
8 30 Light green . . . . . . . . . . . . . . . . . . . . . . Air conditioning compressor/heated seats or air conditioning
compressor/daytime running lights
9 20 Light blue . . . . . . . . . . . . . . . . . . . . . . . ECU (petrol), Cold start solenoid (Diesel)
10 20 Light blue . . . . . . . . . . . . . . . . . . . . . . . Ignition switch
11 3 Violet . . . . . . . . . . . . . . . . . . . . . . . . . . ECU memory
12 15 Light blue . . . . . . . . . . . . . . . . . . . . . . . Horn and hazard flasher warning system
13 15 Light blue . . . . . . . . . . . . . . . . . . . . . . . Oxygen sensor
14 15 Light blue . . . . . . . . . . . . . . . . . . . . . . . Fuel pump
15 10 Red . . . . . . . . . . . . . . . . . . . . . . . . . . . Dipped beam headlight (right-hand side)
16 10 Red . . . . . . . . . . . . . . . . . . . . . . . . . . . Dipped beam headlight (left-hand side)
17 10 Red . . . . . . . . . . . . . . . . . . . . . . . . . . . Main beam headlight (right-hand side)
18 10 Red . . . . . . . . . . . . . . . . . . . . . . . . . . . Main beam headlight (left-hand side)
12•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
12
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Fuses (main fusebox in passenger compartment)
Note:Fuse ratings and circuits are liable to change from year to year. Consult the handbook supplied with the vehicle, or consult a Ford dealer,
for specific information.
Fuse Rating Colour Circuit(s) protected
19 7.5 Brown . . . . . . . . . . . . . . . . . . . . . . . . . Heated door mirrors
20 10 Black . . . . . . . . . . . . . . . . . . . . . . . . . . Front/rear wiper motor (circuit breaker)
21 30 Light green . . . . . . . . . . . . . . . . . . . . . . Front electric windows (only)
21 40 Orange . . . . . . . . . . . . . . . . . . . . . . . . . Front and rear electric windows
22 7.5 Brown . . . . . . . . . . . . . . . . . . . . . . . . . ABS module
23 15 Light blue . . . . . . . . . . . . . . . . . . . . . . . Reversing lights
24 15 Light blue . . . . . . . . . . . . . . . . . . . . . . . Stop-lights
25 20 Yellow . . . . . . . . . . . . . . . . . . . . . . . . . Central locking system/double-locking/anti-theft alarm
26 20 Yellow . . . . . . . . . . . . . . . . . . . . . . . . . Foglights
27 15 Light blue . . . . . . . . . . . . . . . . . . . . . . . Cigar lighter
28 30 Light green . . . . . . . . . . . . . . . . . . . . . . Headlight washer system
29 30 Light green . . . . . . . . . . . . . . . . . . . . . . Heated rear window
30 7.5 Brown . . . . . . . . . . . . . . . . . . . . . . . . . Interior lighting and auxiliary warning system
31 7.5 Brown . . . . . . . . . . . . . . . . . . . . . . . . . Instrument panel illumination
32 7.5 Brown . . . . . . . . . . . . . . . . . . . . . . . . . Radio
33 7.5 Brown . . . . . . . . . . . . . . . . . . . . . . . . . Front and rear sidelights (left-hand side)
34 7.5 Brown . . . . . . . . . . . . . . . . . . . . . . . . . Interior lighting and digital clock
35 7.5 Brown . . . . . . . . . . . . . . . . . . . . . . . . . Front and rear sidelights (right-hand side)
36 30 Light green . . . . . . . . . . . . . . . . . . . . . . Air bag
37 30 Light green . . . . . . . . . . . . . . . . . . . . . . Heater blower
38 7.5 Brown . . . . . . . . . . . . . . . . . . . . . . . . . Adaptive damping
Relays (auxiliary fusebox in engine compartment)
Relay Colour Circuit(s) protected
R1 Green . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Daytime running lights (left-hand-drive, but not all countries) or dim-
dip lights (UK)
R2 Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Radiator electric cooling fan (high speed)
R3 Blue (petrol) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Air conditioning cut-out
R3 Brown (Diesel) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Air conditioning in conjunction with Diesel engine
R4 Yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Windscreen heater time delay
R5 Dark green (petrol) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Radiator electric cooling fan (low speed)
R5 Black (Diesel) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Radiator electric cooling fan (low speed)
R6 Yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Starter solenoid
R7 Brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Horns
R8 Brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel pump
R9 White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dipped beam headlights
R10 White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Main beam headlights
R11 Brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ECU power supply (petrol), cold start (Diesel)
Relays (main fusebox in passenger compartment)
Relay Colour Circuit(s) protected
R12 White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Interior, courtesy and footwell lights
R13 Yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heated rear window
R14 Yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heater blower
R15 Green . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Windscreen wiper motor
R16 Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ignition
Auxiliary relays (not in the fuseboxes)
Relay Colour Circuit(s) protected Location
R17 Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diesel glow plug Battery tray
R18 Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . “One-touch down” Driver’s door
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . driver’s window relay
R19 Blue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Speed control cut-off Central fuse box bracket the
below instrument panel
R20 Blue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Headlight washer system Bulb module bracket
R21 Orange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rear screen wiper interval Bulb module bracket
R22 White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Foglights (left-hand-drive only) Interface module bracket
R23 Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Direction indicators Steering column
R24 White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anti-theft alarm (left-hand side) Door lock module bracket
R25 White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anti-theft alarm (right-hand side) Door lock module bracket
R26 Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heated seats Door lock module bracket
12•2 Body electrical system
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compartment, but on Estate models, it is on
the right-hand side.
Some models are fitted with a headlight
levelling system, which is controlled by a knob
on the facia. On position “0”, the headlights
are in their base position, and on position “5”,
the headlights are in their maximum inclined
angle.
It should be noted that, when portions of
the electrical system are serviced, the cable
should be disconnected from the battery
negative terminal, to prevent electrical shorts
and fires.
Caution: When disconnecting the
battery for work described in the
following Sections, refer to
Chapter 5, Section 1.
Note:Refer to the precautions given in
“Safety first!” and in Section 1 of this Chapter
before starting work. The following tests relate
to testing of the main electrical circuits, and
should not be used to test delicate electronic
circuits (such as engine management systems,
anti-lock braking systems, etc), particularly
where an electronic control module is used.
Also refer to the precautions given in Chapter
5, Section 1.
General
1A typical electrical circuit consists of an
electrical component, any switches, relays,
motors, fuses, fusible links or circuit breakers
related to that component, and the wiring and
connectors which link the component to both
the battery and the chassis. To help to
pinpoint a problem in an electrical circuit,
wiring diagrams are included at the end of this
manual.
2Before attempting to diagnose an electrical
fault, first study the appropriate wiring
diagram, to obtain a complete understanding
of the components included in the particular
circuit concerned. The possible sources of a
fault can be narrowed down by noting if other
components related to the circuit are
operating properly. If several components or
circuits fail at one time, the problem is likely to
be related to a shared fuse or earth
connection.
3Electrical problems usually stem from
simple causes, such as loose or corroded
connections, a faulty earth connection, a
blown fuse, a melted fusible link, or a faulty
relay (refer to Section 3 for details of testing
relays). Visually inspect the condition of all
fuses, wires and connections in a problem
circuit before testing the components. Use
the wiring diagrams to determine which
terminal connections will need to be checked
in order to pinpoint the trouble-spot.
4The basic tools required for electrical fault-
finding include a circuit tester or voltmeter (a
12-volt bulb with a set of test leads can alsobe used for certain tests); an ohmmeter (to
measure resistance and check for continuity);
a battery and set of test leads; and a jumper
wire, preferably with a circuit breaker or fuse
incorporated, which can be used to bypass
suspect wires or electrical components.
Before attempting to locate a problem with
test instruments, use the wiring diagram to
determine where to make the connections.
5To find the source of an intermittent wiring
fault (usually due to a poor or dirty
connection, or damaged wiring insulation), a
“wiggle” test can be performed on the wiring.
This involves wiggling the wiring by hand to
see if the fault occurs as the wiring is moved.
It should be possible to narrow down the
source of the fault to a particular section of
wiring. This method of testing can be used in
conjunction with any of the tests described in
the following sub-Sections.
6Apart from problems due to poor
connections, two basic types of fault can
occur in an electrical circuit - open-circuit, or
short-circuit.
7Open-circuit faults are caused by a break
somewhere in the circuit, which prevents
current from flowing. An open-circuit fault will
prevent a component from working.
8Short-circuit faults are caused by a “short”
somewhere in the circuit, which allows the
current flowing in the circuit to “escape” along
an alternative route, usually to earth. Short-
circuit faults are normally caused by a
breakdown in wiring insulation, which allows a
feed wire to touch either another wire, or an
earthed component such as the bodyshell. A
short-circuit fault will normally cause the
relevant circuit fuse to blow.
Finding an open-circuit
9To check for an open-circuit, connect one
lead of a circuit tester or the negative lead of a
voltmeter either to the battery negative
terminal or to a known good earth.
10Connect the other lead to a connector in
the circuit being tested, preferably nearest to
the battery or fuse. At this point, battery
voltage should be present, unless the lead
from the battery or the fuse itself is faulty
(bearing in mind that some circuits are live
only when the ignition switch is moved to a
particular position).
11Switch on the circuit, then connect the
tester lead to the connector nearest the circuit
switch on the component side.
12If voltage is present (indicated either by
the tester bulb lighting or a voltmeter reading,
as applicable), this means that the section of
the circuit between the relevant connector
and the switch is problem-free.
13Continue to check the remainder of the
circuit in the same fashion.
14When a point is reached at which no
voltage is present, the problem must lie
between that point and the previous test point
with voltage. Most problems can be traced to
a broken, corroded or loose connection.
Finding a short-circuit
15To check for a short-circuit, first
disconnect the load(s) from the circuit (loads
are the components which draw current from
a circuit, such as bulbs, motors, heating
elements, etc).
16Remove the relevant fuse from the circuit,
and connect a circuit tester or voltmeter to the
fuse connections.
17Switch on the circuit, bearing in mind that
some circuits are live only when the ignition
switch is moved to a particular position.
18If voltage is present (indicated either by
the tester bulb lighting or a voltmeter reading,
as applicable), this means that there is a
short-circuit.
19If no voltage is present during this test,
but the fuse still blows with the load(s)
reconnected, this indicates an internal fault in
the load(s).
Finding an earth fault
20The battery negative terminal is
connected to “earth” - the metal of the
engine/transmission unit and the vehicle body
- and many systems are wired so that they
only receive a positive feed, the current
returning via the metal of the car body. This
means that the component mounting and the
body form part of that circuit. Loose or
corroded mountings can therefore cause a
range of electrical faults, ranging from total
failure of a circuit, to a puzzling partial failure.
In particular, lights may shine dimly (especially
when another circuit sharing the same earth
point is in operation), motors (eg wiper motors
or the radiator cooling fan motor) may run
slowly, and the operation of one circuit may
have an apparently-unrelated effect on
another. Note that on many vehicles, earth
straps are used between certain components,
such as the engine/transmission and the
body, usually where there is no metal-to-
metal contact between components, due to
flexible rubber mountings, etc.
21To check whether a component is
properly earthed, disconnect the battery (refer
to Chapter 5, Section 1) and connect one lead
of an ohmmeter to a known good earth point.
Connect the other lead to the wire or earth
connection being tested. The resistance
reading should be zero; if not, check the
connection as follows.
22If an earth connection is thought to be
faulty, dismantle the connection, and clean
both the bodyshell and the wire terminal (or
the component earth connection mating
surface) back to bare metal. Be careful to
remove all traces of dirt and corrosion, then
use a knife to trim away any paint, so that a
clean metal-to-metal joint is made. On
reassembly, tighten the joint fasteners
securely; if a wire terminal is being refitted,
use serrated washers between the terminal
and the bodyshell, to ensure a clean and
secure connection. When the connection is
2 Electrical fault finding -
general information
12•4 Body electrical system
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remade, prevent the onset of corrosion in the
future by applying a coat of petroleum jelly or
silicone-based grease, or by spraying on (at
regular intervals) a proprietary ignition sealer
such as Holts Damp Start, or a water-
dispersant lubricant such as Holts Wet Start.
Note:It is important to note that the ignition
switch and the appropriate electrical circuit
must always be switched off before any of the
fuses (or relays) are removed and renewed. In
the event of the fuse/relay unit having to be
removed, the battery earth lead must be
disconnected. When reconnecting the battery,
reference should be made to Chapter 5.
1Fuses are designed to break a circuit when
a predetermined current is reached, in order
to protect components and wiring which
could be damaged by excessive current flow.
Any excessive current flow will be due to a
fault in the circuit, usually a short-circuit (see
Section 2). The main fusebox, which also
carries some relays, is located inside the
vehicle below the facia panel on the
passenger’s side, and is accessed by a lever
behind the glovebox (see illustration).
2A central timer module is located on the
bottom of the main fusebox. This module
contains the time control elements for the
heated rear window, interior lights and
intermittent wiper operation. The module also
activates a warning buzzer/chime when the
vehicle is left with the lights switched on, or if
a vehicle fitted with automatic transmission is
not parked in position “P”.
3The auxiliary fusebox is located on the front
left-hand side of the engine compartment,
and is accessed by unclipping and removing
the cover. The auxiliary fusebox also contains
some relays (see illustration). Each circuit is
identified by numbers on the main fusebox
and on the inside of the auxiliary fusebox
cover. Reference to the fuse chart in the
Specifications at the start of this Chapter will
indicate the circuits protected by each fuse.
Plastic tweezers are attached to the main
fusebox and to the inside face of the auxiliary
fuse and block cover, to remove and fit the
fuses and relays.
4To remove a fuse, use the tweezers
provided to pull it out of the holder. Slide the
fuse sideways from the tweezers. The wire
within the fuse is clearly visible, and it will be
broken if the fuse is blown (see illustration).
5Always renew a fuse with one of an
identical rating. Never substitute a fuse of a
higher rating, or make temporary repairs using
wire or metal foil; more serious damage, or
even fire, could result. The fuse rating is
stamped on top of the fuse. Never renew a
fuse more than once without tracing the
source of the trouble.
6Spare fuses of various current ratings areprovided in the cover of the auxiliary fusebox.
Note that if the vehicle is to be laid up for a
long period, fuse 34 in the main fusebox
should be removed, to prevent the ancillary
electrical components from discharging the
battery.
7Relays are electrically-operated switches,
which are used in certain circuits. The various
relays can be removed from their respective
locations by carefully pulling them from the
sockets. Each relay in the fuseboxes has a
plastic bar on its upper surface to enable the
use of the tweezers. The locations and
3 Fuses, relays and timer
module- testing and renewal
Body electrical system 12•5
12
3.4 The fuses can be checked visually to
determine if they are blown
3.1 Main fusebox layout
1 Fuse/relay removal tweezers 2 Diode 3 Multi-plug connections
3.3 Auxiliary fusebox layout
1 Fuses 1 to 3 3 Relays R2, R5 and R6 5 Relay sockets for relays R1 and R4
2 Fuses 4 to 8, 11 to 14 4 Relays R7 to R11 6 Diode
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functions of the various relays are given in the
Specifications (see illustration).
8If a component controlled by a relay
becomes inoperative and the relay is suspect,
listen to the relay as the circuit is operated. If
the relay is functioning, it should be possible
to hear it click as it is energized. If the relay
proves satisfactory, the fault lies with the
components or wiring of the system. If the
relay is not being energized, then either the
relay is not receiving a switching voltage, or
the relay itself is faulty. (Do not overlook the
relay socket terminals when tracing faults.)
Testing is by the substitution of a known good
unit, but be careful; while some relays are
identical in appearance and in operation,
others look similar, but perform different
functions.9The central timer module located on the
bottom of the main fusebox incorporates its
own self-diagnosis function. Note that
diagnosis cannot take place if the heated rear
window is defective.
10To activate the system, press the heated
rear window button while the ignition is being
switched on, then release the button. Operate
the light switch, washer pump switch and all
of the door switches one after the other, and
check that the buzzer confirms that the input
signals are correct.
11Now move the wiper lever to the
intermittent wipe position, and check the
output signals by operating the same
switches.
12The self-diagnosis function is turned off
by switching the ignition off and on again.
Removal
Ignition switch and lock barrel
1Disconnect the battery negative (earth) lead
(refer to Chapter 5, Section 1).
2Remove the rubber gaiters and locking
rings, then remove the securing screws and
take off the steering column upper and lower
shrouds.
3Insert the ignition key, and turn it to the
accessory position. Using a small screwdriver
or twist drill through the hole in the side of the
lock housing, depress the locking plunger and
withdraw the lock barrel (see illustrations).
4The switch may be removed from the
steering column assembly by disconnecting
the multi-plug, then using a screwdriver to
release the switch retaining tab (see
illustrations).
Windscreen wiper multi-function
switch
5Disconnect the battery negative (earth) lead
(refer to Chapter 5, Section 1).
6Remove the rubber gaiters and locking
rings, then remove the securing screws and
take off the steering column upper shroud.
7Disconnect the multi-plug (see illustration).
8Depress the plastic tab with a screwdriver,
and lift the switch assembly from the steering
column (see illustrations).
4 Switches - removal and refitting
12•6 Body electrical system
3.7 “One-touch down” window relay in the
driver’s door4.3A Depress the locking plunger . . .4.3B . . . and withdraw the ignition lock
barrel
4.7 Disconnecting the multi-plug from the
windscreen wiper multi-function switch4.8A Depress the plastic tab with a
screwdriver . . .
4.4A Release the retaining tab . . .4.4B . . . and remove the ignition switch
4.8B . . . and remove the windscreen wiper
multi-function switch
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