radiator cap FORD SIERRA 1993 2.G Body Electrical System Workshop Manual

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

2On models up to 1987, the reservoir is
located behind the trim panel on the left-hand
side of the luggage compartment (see
illustration). To remove the reservoir proceed
as follows.
3Disconnect the battery negative lead.
4Remove the trim panel.
5Operate the washers to reduce the fluid
level in the reservoir.
6Remove the reservoir filler cap, and
disconnect the wiring plug and water hose.
7Remove the two securing screws and
withdraw the reservoir.
Refitting
8Refitting is a reversal of removal.
Note: On vehicles fitted with foglamps, the
headlamp unit must be removed when the right-
hand headlamp wiper motor is to be removed.
Removal
1Disconnect the battery negative lead.
2Disconnect the washer hose from the
nozzle on the end of the wiper arm, then
remove the wiper arm.
3Pull the washer hose and retainer from the
end of the motor shaft.
4Remove the radiator grille panel.
5Where applicable, prise the trim strip from
the bottom of the headlamp unit for access to
the wiper motor mounting bolts (see
illustrations). 6Remove the two mounting bolts, then
working under the wheel arch, slide the wiper
motor rearwards, disconnect the wiring plug
and withdraw the motor.
Refitting
7Refitting is a reversal of removal, but on
completion adjust the free length of the
washer hose between the nozzle and the
retainer on the motor shaft.
1Disconnect the battery negative lead.
2Remove the radiator grille panel.
Models up to 1987
3Disconnect the headlamp wiring plug(s)
(see illustration).4Remove the three or four headlamp
securing bolts, as applicable, and the lower
sliding clamp bracket bolt on the rear of the
headlamp, then withdraw the headlamp (see
illustrations).
5If required, the headlamp lens can be
removed by releasing the spring clips around
its edge.
6Refitting is a reversal of removal, but the
headlamp securing bolts should not be
tightened until the headlamp is aligned with
the front grille panel.
7On completion, check the headlamp
alignment.
Models from 1987
8Disconnect the headlamp wiring plug(s)
(see illustration).
9Where applicable, remove the headlamp
wiper motor.
41Headlamp unit - removal and
refitting
40Headlamp wiper motor -
removal and refitting
Body electrical system 13•13
13
40.5b . . . for access to the headlamp wiper
motor mounting bolts
41.4d . . . then withdraw the headlamp unit
- models up to 198741.4c . . . and the lower sliding clamp
bracket bolt . . .41.4b . . . the rear securing bolt . . .
41.4a Remove the upper headlamp
securing bolts (arrowed) . . .41.3 Disconnect the headlamp wiring plug
- models up to 1987
40.5a Prise the trim strip from the bottom
of the headlamp unit . . .39.2 Rear window washer fluid reservoir
location - Hatchback models up to 1987.
Securing screws arrowed