bonnet 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

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

21Remove the two securing screws, and
detach the motor from the lock assembly.
22Refitting is a reversal of removal, ensuring
that the motor operating rod engages with the
lock lever.
Note: The alarm system has a self-diagnosis
function, which allows a Ford dealer to carry
out fault diagnosis, using suitable specialist
equipment. In the event of a problem with the
alarm system, it is advisable not to tamper
with the components until appropriate fault
diagnosis has been carried out.Location
1From 1990, certain models are fitted with
an anti-theft alarm(see illustration).
2The alarm system consists of a control
module mounted behind the driver’s side
facia; trip switches fitted to the doors,
tailgate/boot lid, and bonnet; activating
switches fitted to the front door locks; an
additional horn mounted at the bulkhead next
to the battery and an indicator light mounted
on the top of the facia.
Module - removal and refitting
3Disconnect the battery negative lead.
4Release the carpet trim panel from under
the driver’s side facia. 5Reach up behind the facia and locate the
control module. Release the plastic retaining
clips using a screwdriver, and lower the
module.
6Disconnect the wiring plug and withdraw
the module.
7Refitting is a reversal of removal.
Removal
1Disconnect the battery negative lead.
2Remove the seat.
3Remove the seat cushion trim or backrest
trim as necessary.
4Note which way round the pad is fitted,
then remove the wire clips and adhesive tape
which secure it to the seat. Retrieve the tie-
rod and fit it to the new pad.
Refitting
5Fit the new pad with the thermostat facing
the cushion foam(see illustration).Secure
the pad with wire clips and tape, making sure
that it is not too tight - it must be able to flex
when sat on.
6Refit the cushion or backrest trim, as
applicable, being careful not to trap or kink
the pad.
7Refit the seat, reconnect the wiring and
check the pads for correct operation.
52Seat heating pad - removal
and refitting
51Anti-theft alarm - location,
removal and refitting
Body electrical system 13•19
13
50.19b Rear door central locking motor
securing screws (arrowed) -
models from 199050.19a Front door central locking motor
securing screws (arrowed) -
models from 1990
51.1 Anti-theft alarm
system components
A Tailgate/boot lid
switch
B Control module
C Horn
D Bonnet switch
E Door switch
F Activating switch