heating FORD SIERRA 1993 2.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

5To find the source of an intermittent wiring
fault (usually due to a poor or dirty
connection, or damaged wiring insulation), an
integrity test can be performed on the wiring,
which involves moving 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, but will
not cause the relevant circuit fuse to blow.
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.
Note: A short-circuit that occurs in the wiring
between a circuit’s battery supply and its fuse
will not cause the fuse in that particular circuit
to blow. This part of the circuit is unprotected
- bear this in mind when fault-finding on the
vehicle’s electrical system.
Finding an open-circuit
9To check for an open-circuit, connect one
lead of a circuit tester or voltmeter to either
the negative battery terminal or a known good
earth.
10Connect the other lead to a connector in
the circuit being tested, preferably nearest to
the battery or fuse.
11Switch on the circuit, bearing in mind that
some circuits are live only when the ignition
switch is moved to a particular position.
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 battery 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, but the fuse still
blows with the load(s) connected, 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 and the car body - and
most 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 fault. 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, 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
back to bare metal both the bodyshell and the
wire terminal, or the component’s earth
connection mating surface. 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 terminaland the bodyshell, to ensure a clean and
secure connection. When the connection is
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.Location
1The main fuses and relays are located in a
box in the engine compartment on the right-
hand side of the bulkhead. The circuits
protected are identified by symbols on the
underside of the fusebox cover. On certain
models, additional relays and fuses are located
in various positions beneath the facia panels. If
uncertain of the location of an auxiliary relay or
fuse, it is suggested that a Ford dealer is
consulted, as the relay and fuse locations vary
substantially depending on model.
Renewal
2Always renew a fuse with one of identical
rating and never renew it more than once
without finding the source of the trouble
(usually a short circuit). Always switch off the
ignition before renewing a fuse or relay, and
when renewing the wiper motor fuse keep the
hands clear of the wiper linkage as it may
return to the parked position. Note that the
fuses are colour-coded as follows:
10ARed
15ABlue
20AYellow
25ANatural
10AGreen
3Access to the fuses and relays in the
fusebox is gained by removing the loose
cover and spring clip (if fitted), pulling the
plastic clip and removing the cover. All fuses
and relays are a push fit (see illustrations).
The fuse/relay plate can be released from the
fusebox for access to the wiring by carefully
levering the plastic lugs around the perimeter
of the plate.
4For details of direction indicator/hazard
warning flasher relay removal and refitting,
refer to the relevant Section of this Chapter.
3Fuses and relays - location and
renewal
Body electrical system 13•3
13
3.3b Fusebox cover removed to expose
fuses and relays (1.8 CVH model shown)3.3a Remove the loose cover for access to
the fusebox cover

P100 models
43Pull the lamp cover from the rubber
housing to expose the bulb. The bulb is a
bayonet fitting in the bulbholder.
44Refitting is a reversal of removal.
1Disconnect the battery negative lead.
Switches
2Prise the switch from its location using a
thin-bladed screwdriver, and disconnect the
wiring plug (see illustration).
3Refitting is a reversal of removal.
Operating motors
4Remove the window regulator.
5Remove the three securing bolts, and
withdraw the motor from the regulator
assembly (see illustration).
6Refitting is a reversal of removal, but ensure
that the drive gear is correctly meshed with
the regulator.
Note:If a central locking solenoid or motor is
to be renewed due to jamming or overheating,
the central locking relay must be renewed atthe same time even if it is believed to be
working correctly. Before starting work on the
central locking system, unlock all the doors
and the tailgate/boot. Make sure that the keys
are outside the vehicle before reconnecting
the battery on completion of work.
Operation
Models up to 1987
1The central locking system is activated by
turning the key in the driver’s door lock, and
the locks are operated by solenoids.
Models from 1987
2The system is activated by turning the key
in either of the front door locks, and the locks
are operated by electric motors.
Removal and refitting
3Disconnect the battery negative lead.
Models up to 1987
Switch (driver’s door lock)
4Remove the door lock.
5Remove the two securing screws, then
withdraw the switch from the lock assembly
and disconnect the wiring plug.
6Refitting is a reversal of removal, but ensure
that the cut-out in the switch lever engages
with the lock lever (see illustration).
Solenoids (passenger and rear door locks)
7Remove the door lock (see illustration).
8Remove the two securing screws, then
disconnect the solenoid operating rod and thewiring plug and withdraw the solenoid from
the lock assembly.
9Refitting is a reversal of removal.
Solenoid (tailgate lock)
10Open the tailgate and remove the trim
panel.
11Disconnect the solenoid wiring plug and
earth lead, and the operating rod, then
remove the two securing screws and
withdraw the solenoid from the tailgate(see
illustration).
12Refitting is a reversal of removal.
Models from 1987
Motors (door locks)
13Remove the door inner trim panel.
14Remove the retaining screws and
disconnect the wiring plug and the motor
operating rod, then withdraw the motor from
the door.
15Refitting is a reversal of removal.
Motor (tailgate and boot lid locks)
16Open the tailgate/boot lid and where
applicable remove the trim panel.
17Remove the retaining screws and
disconnect the wiring plug and the motor
operating rod, then withdraw the motor from
the tailgate/boot.
18Refitting is a reversal of removal.
Models from 1990
Motors (door locking)
19On models from 1990, the door locking
motors are incorporated in the door lock units
(see illustrations).
20To remove a motor, first remove the door
lock.
50Central door locking
components - operation,
removal and refitting
49Electric window components
- removal and refitting
13•18Body electrical system
48.41 Removing a rear number plate lamp
bulb - Saloon, Hatchback and Estate
models49.5 Electric window motor securing bolts
(arrowed)
50.7 Central door locking assembly -
models up to 1987
A Solenoid
B Door ajar switch (not fitted to all models)
50.6 Driver’s door central locking switch -
models up to 1987
A Switch lever cut-out
49.2 Disconnecting the wiring plug from a
centre console-mounted electric window
switch - models from 1987
50.11 Removing a tailgate lock solenoid -
Hatchback models up to 1987

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

1On models fitted with an electric aerial,
disconnect the battery negative lead.
Saloon and Estate models
2Remove the right-hand side trim panel from
the luggage compartment.
3Working outside the vehicle, unscrew the
nut and remove the spacer and seal from the
base of the aerial.
4Working inside the luggage compartment,
either unscrew the aerial bracket securing
screw and slide the bracket from the aerial
tube, or pull the base of the aerial from the
rubber bush in the bracket, as applicable (see
illustration).
5Ensure that the aerial is fully retracted, then
pull it through the hole in the bodywork into
the luggage compartment (see illustration).
6The aerial lead may be a push-fit in the
base of the aerial, or may be secured by a
knurled nut. Disconnect the aerial lead and
where applicable, disconnect the wiring from
the electric motor. Note that the aerial lead
runs through the roof. If it is necessary to
renew the lead, it may prove easier to leave
the old lead in place and run a new one under
the carpet. Follow existing wiring runs where
possible.
7Refitting is a reversal of removal.
Hatchback models
8Remove the right-hand rear seat side
cushion.
9Remove the rear parcel shelf.
10On “high specification” models, lift the
seat catch release lever, push out the pin
securing the link rod to the lever and
disconnect the link rod.
11Remove the securing screws from the rear
parcel shelf support (nine screws on models
up to 1987, eight screws from 1987 onwards).
Remove the rear parcel shelf support.
12Remove the side trim panel from the
luggage compartment.
13Proceed as described in paragraphs 3 to
7 inclusive.
P100 models
14Pull off the plastic trim cover and unscrew
the aerial securing nut.
15Withdraw the aerial assembly, and
carefully prise the base seal from the roof
panel.
16The aerial lead runs across the roof panel
under the headlining, and down the right-hand
front pillar to the radio unit. Renewal is
straightforward, but the front section of the
headlining must be released for access and a
length of string should be tied to the end of
the aerial lead before removal to aid routing
when refitting.
17The aerial rod can be renewed by simply
unscrewing it from the base.
18Refitting is a reversal of removal.
1Disconnect the battery negative lead.
Saloon models
2Remove both rear seat side cushions.
3Remove the securing screws and withdraw
the rear parcel shelf.
4Make a note of the wiring connections for
use when refitting, then disconnect the wiring,
remove the two securing screws, and
withdraw the amplifier unit (see illustration).
5Refitting is a reversal of removal.
Hatchback models
6Unclip the tailgate trim panel.
7Remove the amplifier bracket securing
screws, and withdraw the amplifier through
the tailgate panel aperture (see illustration).
8Make a note of the wiring connections for
use when refitting, then disconnect the wiring
and remove the amplifier unit.
9Refitting is a reversal of removal.
Estate models
10Unclip the tailgate trim panel.
11Make a note of the wiring connections for
use when refitting, then disconnect the wiring,
remove the four securing screws, and detach
the loudspeaker/amplifier bracket assembly
from the tailgate (see illustration).
12Refitting is a reversal of removal.
1Disconnect the battery earth lead.
Facia panel-mounted speakers
Upper
2Prise the speaker grille from its four
retaining clips in the facia using a thin-bladed
screwdriver.
3Remove the four securing screws,
disconnect the wiring, and pull the
loudspeaker from the facia panel.
4Refitting is a reversal of removal.
55Loudspeakers - removal and
refitting54Integral heated rear
window/radio aerial amplifier
- removal and refitting
53Radio aerial (exterior-
mounted) - removal and
refitting
13•20Body electrical system
52.5 Seat heating pad
Thermostat (arrowed) must face foam53.5 Removing an electric aerial -
Saloon model
54.7 Integral heated rear window/radio
aerial amplifier bracket securing screws
(arrowed) - Hatchback models54.4 Integral heated rear window/radio
aerial amplifier securing screws (arrowed)
- Saloon models
53.4 Pull the base of the aerial from the
rubber bush (arrowed)