Ford Granada 1985-1994, Owner'S Manual

Page: 200 / 254

the circuit between the relevant connector and
the battery is problem-free.
13 Continue to check the remainder of the
circuit in the same fashion.
14 When 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
15 To 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).
16 Remove the relevant fuse from the circuit,
and connect a circuit tester or voltmeter to the
fuse connections.
17 Switch on the circuit, bearing in mind that
some circuits are live only when the ignition
switch is moved to a particular position.
18 If voltage is present (indicated either by
the tester bulb lighting or a voltmeter reading),
this means that there is a short-circuit.
19 If 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
20 The 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 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.
21 To 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.
22 If 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 terminal and
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, or a
water-dispersant lubricant.
Headlight
1 Open and prop the bonnet. Remove the
cover from the rear of the headlight unit by
twisting it anti-clockwise.
2 Disconnect the wiring plug from the
headlight bulb. Release the spring clip by
squeezing its legs together and move it clear
of the bulb (see illustration).
3 Remove the headlight bulb (see
illustration).
Caution: If the lights have just
been in use, the bulb may be extremely hot.
4 When handling the new bulb, use a tissue or
clean cloth to avoid touching the glass with
the fingers. If the glass is accidentally touched,
wipe it clean using methylated spirit. Moisture
and grease from the skin can cause
blackening and rapid failure of the new bulb.
5 Fit the new bulb, making sure that the legs
and cut-outs in the bulb base and the reflector
match up. Secure with the spring clip.
6 Reconnect the wiring plug. Check the
headlight for correct operation, then refit and
secure the rear cover.
Front parking light (sidelight)
7 Gain access as for the headlight bulb, then
pull the parking light bulbholder from the
headlight reflector.
8 Extract the wedge base bulb from the
holder (see illustration). Fit the new bulb, refit
the bulbholder and check for correct
operation.
Auxiliary driving light (when fitted)
9 From above the auxiliary light unit, release
the cover spring clip and remove the cover
(see illustration).
10 Release the spring clip from the bulb.
Withdraw the bulb and unplug its wiring
connector (see illustration). Caution: If the
lights have just been in use, the bulb may be
extremely hot.
11 Do not touch the glass of the new bulb
with the fingers.
3 Exterior lights - bulb renewal
13•4 Body electrical system
3.2 Squeeze the spring clip legs (arrowed)
to remove the headlight bulb
3.3 Removing a headlight bulb
3.8 Removing the front parking light bulb
from the holder
3.9 Auxiliary driving light cover 3.10 Removing the auxiliary driving light
bulb