brake FORD SIERRA 1986 1.G Body Electrical System Workshop Manual

Chapter 13
Body electrical system
Anti-theft alarm - location, removal and refitting . . . . . . . . . . . . . . . .51
Auxiliary warning system components - location, testing, removal and
refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Brake lamp switch - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Central door locking components - operation, removal and refitting .50
Cigarette lighter - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Clock - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Courtesy lamp and luggage compartment lamp - renewal . . . . . . . .25
Courtesy lamp switch - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Direction indicator and hazard warning flasher switch assembly -
renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Direction indicator/hazard warning flasher relay - renewal . . . . . . . . .6
Electrical door mirror switch - removal and refitting . . . . . . . . . . . . .10
Electrical fault finding - general information . . . . . . . . . . . . . . . . . . . . .2
Electric sunroof components - removal and refitting . . . . . . . . . . . . .17
Electric window components - removal and refitting . . . . . . . . . . . . .49
Exterior lamp bulbs - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
Facia panel switches - removal and refitting . . . . . . . . . . . . . . . . . . . .9
Front direction indicator lamp unit - removal and refitting . . . . . . . . .44
Front direction indicator side repeater lamp - removal and refitting . .45
Front foglamps - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . .46
Fuses and relays - location and renewal . . . . . . . . . . . . . . . . . . . . . . .3
General information and precautions . . . . . . . . . . . . . . . . . . . . . . . . .1
Handbrake “on” warning lamp switch - renewal . . . . . . . . . . . . . . . .14
Headlamps - alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Headlamp unit - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . .41
Headlamp wiper motor - removal and refitting . . . . . . . . . . . . . . . . . .40
Horn - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Horn switch assembly - removal and refitting . . . . . . . . . . . . . . . . . .11
Ignition switch and lock barrel - removal and refitting . . . . . . . . . . . . .4
Instrument panel - removal and refitting . . . . . . . . . . . . . . . . . . . . . .20Instrument panel components - removal and refitting . . . . . . . . . . . .21
Integral heated rear window/radio aerial amplifier - removal and
refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
Interior lamp bulbs - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Lighting and wash/wipe switch assembly - renewal. . . . . . . . . . . . . . .7
“Lights-on” warning module - renewal . . . . . . . . . . . . . . . . . . . . . . . .24
Loudspeakers - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . .55
Luggage compartment lamp switch - removal and refitting . . . . . . .13
Map reading lamp - removal and refitting . . . . . . . . . . . . . . . . . . . . .26
Oil pressure warning lamp switch - renewal . . . . . . . . . . . . . . . . . . . .16
Radio aerial (exterior-mounted) - removal and refitting . . . . . . . . . . .53
Radio/cassette player - removal and refitting . . . . . . . . . . . . . . . . . . .57
Radio/cassette player power amplifier - removal and refitting . . . . . .56
Rear lamp unit - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . .43
Rear number plate lamp - removal and refitting . . . . . . . . . . . . . . . . .47
Rear window washer fluid reservoir - removal and refitting . . . . . . . .39
Rear window washer pump - removal and refitting . . . . . . . . . . . . . .38
Rear window wiper motor - removal and refitting . . . . . . . . . . . . . . .37
Reversing lamp switch - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Seat heating pad - removal and refitting . . . . . . . . . . . . . . . . . . . . . .52
Speedometer cable - removal and refitting . . . . . . . . . . . . . . . . . . . .30
Trip computer components - removal and refitting . . . . . . . . . . . . . .22
Underbonnet lamp - removal, refitting and bulb renewal . . . . . . . . . .28
Washer nozzles - removal and refitting . . . . . . . . . . . . . . . . . . . . . . .33
Windscreen/headlamp washer fluid reservoir - removal and refitting . .36
Windscreen/headlamp washer pump - removal and refitting . . . . . .35
Windscreen wiper motor and linkage - removal and refitting . . . . . . .34
Wiper arms - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Wiper blades - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Wiring diagrams - general information . . . . . . . . . . . . . . . . . . . . . . . .58
13•1
Contents
13Easy,suitable for
novice with little
experienceFairly easy,suitable
for beginner with
some experienceFairly difficult,
suitable for competent
DIY mechanic
Difficult,suitable for
experienced DIY
mechanicVery difficult,
suitable for expert
DIY or professional
Degrees of difficulty

System type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 volt, negative earth
BulbsFittingsWattage
Halogen headlamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .H460/55
Auxiliary driving lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .H355
Front foglamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .H355
Side lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Glass base5
Direction indicator lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bayonet21
Brake/tail lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bayonet21/4
Reversing lamp(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bayonet21
Rear foglamp(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bayonet21
Rear number plate lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Glass base5
Luggage compartment lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bayonet10
Underbonnet lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bayonet10
Courtesy lamp(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bayonet10
Map reading lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Glass base5
Vanity mirror illumination lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Festoon3
Glove compartment lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Glass base3
Ashtray lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Glass base1.2
Warning lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Glass base1.2 or 2.5
Instrument illumination lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Glass base1.2 or 2.5
Heater control illumination lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Glass base1
Automatic transmission gear selector lamp . . . . . . . . . . . . . . . . . . . . . .Bayonet1.2
Clock illumination lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bayonet1.4
Cigarette lighter lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Glass base1.2
Torque wrench settingsNmlbf ft
Trip computer fuel flow sensor unit fuel pipe unions . . . . . . . . . . . . . . .14 to 1710 to 13
General information
The electrical system is of the 12 volt.
negative earth type. Electricity is generated by
an alternator, belt-driven from the crankshaft
pulley. A lead-acid storage battery provides a
reserve of power for starting and when the
demands of the system temporarily exceed
the alternator output.
The battery negative terminal is connected
to “earth” - vehicle metal - and most electrical
system components are wired so that they
only receive a positive feed, the current
returning via vehicle metal. This means that
the component mounting forms part of the
circuit. Loose or corroded mountings can
therefore cause apparent electrical faults.
Many semiconductor devices are used in
the electrical system, both in the “black
boxes” which control vehicle functions and in
other components. Semiconductors are very
sensitive to excessive (or wrong polarity)
voltage, and to extremes of heat. Observe the
appropriate precautions to avoid damage.
Precautions
It is necessary to take extra care when
working on the electrical system to avoid
damage to semi-conductor devices (diodes
and transistors), and to avoid the risk of
personal injury. In addition to the precautions
given in the
“Safety first!” Section at the
beginning of this manual, take note of the
following points when working on the system.
Always remove rings, watches, etc before
working on the electrical system. Even withthe battery disconnected, capacitive
discharge could occur if a component live
terminal is earthed through a metal object.
This could cause a shock or nasty burn.
Do not reverse the battery connections.
Components such as the alternator or any
other having semi-conductor circuitry could
be irreparably damaged.
If the engine is being started using jump
leads and a slave battery, connect the
batteries positive to positive and negative to
negative. This also applies when connecting a
battery charger.
Never disconnect the battery terminals, or
alternator multi-plug connector, when the
engine is running.
The battery leads and alternator multi-plug
must be disconnected before carrying out any
electric welding on the car.
Never use an ohmmeter of the type
incorporating a hand cranked generator for
circuit or continuity testing.
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
anti-lock braking systems), particularly where an
electronic control unit (ECU) is involved.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 andconnectors 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 Chapter.
2Before attempting to diagnose an electrical
fault, first study the appropriate wiring
diagram, to obtain a more complete
understanding of the components included in
the particular circuit concerned. The possible
sources of a fault can be narrowed down by
noting whether 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. 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 also
be used for certain tests), a self-powered test
light (sometimes known as a continuity tester),
an ohmmeter (to measure resistance), 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.
2Electrical fault-finding - general
information
1General information and
precautions
13•2Body electrical system
Specifications

Removal
1Disconnect the battery negative lead.
2For improved access, remove the securing
screws and unclip the lower and upper
steering column shrouds.
3Insert the ignition key and turn to position
“I”, then, working through the access hole,
depress the spring clip using a suitable tool
and pull the key to withdraw the lock barrel
and cylinder from the ignition switch housing.
The spring clip access hole is shown (see
illustration). Note that, on certain models, the
spring clip must be released by inserting the
tool through a small circular hole at the top of
the switch housing, above the rectangular slot
shown. Slight movement of the key may be
necessary to allow removal of the barrel and
cylinder.
4To remove the lock barrel from the cylinder
insert the key fully into the barrel and remove
the retaining circlip, taking care not to
damage the circlip location, then withdraw the
key approximately 5.0 mm (0.2 in) to retract
the lock barrel securing lug, and withdraw the
barrel from the cylinder.
5To remove the ignition switch, disconnect
the wiring plug, then remove the two grub
screws and withdraw the switch.
Refitting
6Refitting is a reversal of removal, bearing in
mind the following points.
7Note that the lock barrel can only be fitted
to the cylinder in one position, and check with
the key fully inserted that the barrel can be
turned from position “O” to “Ill” satisfactorily.
8The open jaws of the lock barrel retaining
circlip must align with the keyway register on
the cylinder, and the cylinder retaining circlip
must locate in the slot in the ignition switch
housing.
9On completion, check the operation of the
steering lock and ignition switch in all
positions.
1Disconnect the battery negative lead.
2Remove the securing screws and unclip the
lower and upper steering column shrouds.
3Remove the two securing screws and
disconnect the two wiring plugs, then
withdraw the switch from the steering column.
4Refitting is a reversal of removal.
1Disconnect the battery negative lead.2The relay is located on a bracket above the
steering column. Access is gained either by
removing the driver’s side lower facia panel or
the instrument panel.
3Unclip the relay from the bracket, and
disconnect the wiring plug (see illustration).
4Refitting is a reversal of removal. Check for
correct operation before refitting the facia
panel or instrument panel.
The procedure is identical to that described
for the direction indicator switch, except for
the additional removal and refitting of an earth
lead (see illustration).
1For automatic transmission models, refer to
Chapter 7, PartB. For manual gearbox
models, proceed as follows:
2Disconnect the battery negative lead.
3Apply the handbrake, jack up the front of
the vehicle and support on axle stands (see
“Jacking and Vehicle Support”).
4Working underneath the vehicle,
disconnect the wiring plug, then unscrew the
switch from the gearbox extension housing.
5Refitting is a reversal of removal, but make
sure that the wiring is routed clear of the
exhaust system.1Disconnect the battery negative lead.
Rocker switches and push button
switches
2Using a thin-bladed screwdriver, carefully
prise the switch from the facia panel.
3Disconnect the wiring plug and withdraw
the switch.
4Refitting is a reversal of removal.
Instrument panel illumination and
intermittent wipe rheostats
5Proceed as described in paragraphs 2 to 4.
Heater blower switch
6Carefully pull off the switch knob, using
pliers with padded jaws if necessary.
7Using a thin-bladed screwdriver, prise out
the switch front plate from the facia panel.
8Squeeze the switch retaining tabs, then
withdraw the switch and disconnect the wiring
plug (see illustration).
9Refitting is a reversal of removal.
Loudspeaker balance joystick
10Using a thin-bladed screwdriver, carefully
prise the joystick front plate from the facia
panel.
11Twist the joystick assembly retaining ring
anti-clockwise and remove the ring.
12Working behind the facia panel,
disconnect the wiring plug and slide out the
joystick assembly.
9Facia panel switches - removal
and refitting
8Reversing lamp switch -
renewal
7Lighting and wash/wipe
switch assembly - renewal
6Direction indicator/hazard
warning flasher relay - renewal
5Direction indicator and hazard
warning flasher switch
assembly - renewal
4Ignition switch and lock barrel
- removal and refitting
13•4Body electrical system
4.3 Ignition switch lock barrel spring clip
location (arrowed)
7.1 Lighting and wash/wipe switch
assembly earth lead securing screw
(arrowed)9.8 Heater blower switch removal. Switch
retaining tabs arrowed
6.3 Direction indicator/hazard warning
flasher relay location (arrowed)

7Unclip the switch from the lock assembly,
disconnect the wiring plug and remove the
switch.
8Refitting is a reversal of removal.
1Disconnect the battery negative lead.
2Working inside the vehicle, remove the
handbrake lever rubber gaiter and/or the
centre console, as necessary.
3Disconnect the wiring connector from the
switch, then remove the two securing screws
and withdraw the switch from the handbrake
lever (see illustration).
4Refitting is a reversal of removal.
1Disconnect the battery negative lead.
2Unclip the trim panel from the lower edge of
the driver’s side lower facia trim panel. If
required for improved access, remove the
lower facia trim panel.
3Disconnect the wiring from the terminal on
the switch, then twist the switch anti-
clockwise and remove it (see illustration).
4When refitting, insert the switch into its
aperture in the pedal bracket, then push the
switch inwards until the switch barrel touches
the pedal. Ensure that the pedal is not moved
from its stop. Twist the switch clockwise to lock
it in position. No further adjustment is necessary.
5Further refitting is a reversal of removal, but
check the operation of the switch on
completion.
1Disconnect the battery negative lead.
2The switch is located towards the left-hand
rear of the cylinder block on SOHC models
(see illustration), towards the right-hand rear
of the cylinder block on CVH models and on
the right-hand side of the cylinder block,
between the core plugs, on DOHC models.3Disconnect the wiring from the switch
terminal, then unscrew and withdraw the
switch. Be prepared for some oil spillage.
4Clean the threads of the switch and its seat
before refitting.
5After refitting, run the engine and check for
oil leaks around the switch, then stop the
engine and check the oil level, topping-up if
necessary.
Switch
1Disconnect the battery negative lead.
2Using a thin-bladed screwdriver, carefully
prise the switch from the overhead console.
3Disconnect the wiring plug and remove the
switch.
4Refitting is a reversal of removal.
Relay
5Remove the overhead console.
6Unclip the relay from the motor assembly
and disconnect the wiring plug (see
illustration).
7Refitting is a reversal of removal.
Motor
8Remove the overhead console.
9Disconnect the motor wiring plug.
10Unscrew the three securing bolts, and
withdraw the motor assembly from the roof.
11Refitting is a reversal of removal, but
ensure that the drive gear is aligned with the
roof operating mechanism.1Disconnect the battery negative lead.
2Working behind the facia panel, disconnect
the wiring, then push out the lighter assembly
through the front of the facia panel.
3If required, the illumination ring assembly
can now be withdrawn after removing the
bulbholder.
4Refitting is a reversal of removal.
1Disconnect the battery negative lead.
Standard clock
2Using a thin-bladed screwdriver, carefully
prise the clock from the facia panel.
3Disconnect the wiring plug and withdraw
the clock.
4Refitting is a reversal of removal.
Multi-function digital/analogue
clock
5Remove the single screw from the top edge
of the facia panel in which the clock is
housed, then withdraw the facia panel.
6Remove the four now exposed securing
screws, disconnect the wiring plug, and
withdraw the clock (see illustration).
7Refitting is a reversal of removal.
19Clock - removal and refitting
18Cigarette lighter - renewal
17Electric sunroof components
- removal and refitting
16Oil pressure warning lamp
switch - renewal
15Brake lamp switch - renewal
14Handbrake “on” warning
lamp switch - renewal
13•6Body electrical system
14.3 Handbrake “on” warning lamp switch
location (arrowed)
16.2 Oil pressure warning lamp switch
location (arrowed) - SOHC engine19.6 Multi-function digital/analogue clock
securing screws (arrowed)17.6 Electric sunroof relay (A) and motor
securing bolts (B)
15.3 Brake lamp switch location (arrowed)

Clock illumination lamp
26Remove the clock.
27The bulb is a bayonet fit in the rear of the
clock.
28Refitting is a reversal of removal.
1Disconnect the battery negative lead.
Removal and refitting
2Detach the wiring connector at the left-hand
bonnet hinge, and attach a length of string to
the end of the wire running from the lamp.
3If necessary, remove the underbonnet
insulation by prising out the two-piece plastic
securing clips, then working at the lamp, pull the
wiring and the string through the bonnet panel.
4Detach the string from the end of the wire,
and remove the screw securing the lamp to
the bonnet. Withdraw the lamp.
5Commence refitting by attaching the end of
the wiring to the string, and pulling the string
and wiring through the bonnet panel. Further
refitting is a reversal of removal.
Bulb renewal
6Simply press and twist the bulb to remove it
from the bulbholder (see illustration).
7Refitting is a reversal of removal.
Removal
1The horn(s) is/are located in front of the
radiator beneath the front panel (see
illustration). The horn(s) may be located on
either side of the vehicle depending on model.
2Disconnect the battery negative lead.
3Disconnect the wiring from the horn, then
unscrew the securing nut and washer and
withdraw the horn and bracket assembly
complete.
4Repeat the operations for the remaining
horn where applicable.
Refitting
5Refitting is a reversal of removal.
Removal
1On models fitted with a trip computer,
remove the speed sender unit.
2Remove the instrument panel.
3Pull the cable through the bulkhead into the
engine compartment, and where applicable
release it from the securing clips. On models
fitted with a trip computer, the upper section
of the cable can now be removed.
4Apply the handbrake, jack up the front of
the vehicle and support on axle stands (see
“Jacking and Vehicle Support”).
5On vehicles with a manual gearbox, extract
the circlip securing the cable end to the
extension housing and withdraw the cable
end (see illustration).
6On vehicles with automatic transmission,
remove the securing screw and disconnect
the cable end from the extension housing.
7The cable can now be withdrawn from the
vehicle, noting its routing so that it can be
refitted in the same position.
Refitting
8Refitting is a reversal of removal, but where
applicable, ensure that the speedometer
cable rubber sleeve is in place over the square
inner drive on the cable connector, and not in
the speedometer head. Position the cable so
that the coloured bands on the cable sheath
line up with the bulkhead grommet and the
clips in the engine compartment. Route the
cable as noted during removal.9On completion, pull the speedometer cable
from within the engine compartment to ensure
that the cable is straight between the
instrument panel and the bulkhead grommet.
1The wiper blades should be renewed when
they no longer clean the glass effectively.
2Lift the wiper arm away from the glass.
3With the blade at 90º to the arm, depress
the spring clip and slide the blade clear of the
hook, then slide the blade up off the arm.
4If necessary extract the two metal inserts
and unhook the wiper rubber.
5Fit the new rubber and blade in reverse
order, making sure where necessary that the
cut-outs in the metal inserts face each other.
Windscreen and rear wipers
1Lift the hinged covers and remove the nuts
and washers securing the arms to the spindles.
2Mark the arms and spindles in relation to each
other then prise off the arms using a screwdriver.
Take care not to damage the paintwork.
3Refitting is a reversal of removal.
Headlamp wipers
4The procedure is as described in
paragraphs 1 to 3, but the washer hose must
be disconnected from the nozzle on the wiper
arm (see illustration).
32Wiper arms - removal and
refitting
31Wiper blades - renewal
30Speedometer cable - removal
and refitting
29Horn - removal and refitting
28Underbonnet lamp - removal,
refitting and bulb renewal
Body electrical system 13•11
13
29.1 Horn location beneath front panel
30.5 Speedometer cable end fitting in
manual gearbox extension housing
28.6 Removing an underbonnet lamp bulb27.24 Removing a luggage compartment
lamp bulb
32.4 Removing a headlamp wiper arm