dashboard FORD MONDEO 1993 Service Repair Manual

5Undo the sensor’s retaining screw and
withdraw the sensor. The sensor’s bracket
cannot be unbolted from the cylinder
block/crankcase unless the transmission and
flywheel/driveplate have been removed (see
Chapter 2).
6Refitting is the reverse of the removal
procedure.
General information
The charging system includes the
alternator, an internal voltage regulator, a no-
charge (or “ignition”) warning light, the
battery, and the wiring between all the
components. The charging system supplies
electrical power for the ignition system, the
lights, the radio, etc. The alternator is driven
by the auxiliary drivebelt at the front (right-
hand end) of the engine.
The purpose of the voltage regulator is to
limit the alternator’s voltage to a preset value.
This prevents power surges, circuit overloads,
etc., during peak voltage output.
The charging system doesn’t ordinarily
require periodic maintenance. However, the
drivebelt, battery and wires and connections
should be inspected at the intervals outlined
in Chapter 1.
The dashboard warning light should come
on when the ignition key is turned to positions
“II” or “III”, then should go off immediately the
engine starts. If it remains on, or if it comes on
while the engine is running, there is a
malfunction in the charging system (see
Section 11). If the light does not come on
when the ignition key is turned, and the bulb is
sound (see Chapter 12), there is a fault in the
alternator.
Precautions
Be very careful when making electrical
circuit connections to a vehicle equipped with
an alternator, and note the following:
(a) When reconnecting wires to the alternator
from the battery, be sure to note the
polarity.
(b) Before using arc-welding equipment to
repair any part of the vehicle, disconnect
the wires from the alternator and the
battery terminals.
(c) Never start the engine with a battery
charger connected.
(d) Always disconnect both battery leads
before using a battery charger.
(e) The alternator is driven by an engine
drivebelt which could cause serious injury
if your hand, hair or clothes become
entangled in it with the engine running.
(f) Because the alternator is connected
directly to the battery, it could arc or
cause a fire if overloaded or shorted-out.
(g) Wrap a plastic bag over the alternator,
and secure it with rubber bands, beforesteam-cleaning or pressure-washing the
engine.
(h) Never disconnect the alternator terminals
while the engine is running.
1If a malfunction occurs in the charging
circuit, don’t automatically assume that the
alternator is causing the problem. First check
the following items:
(a) Check the tension and condition of the
auxiliary drivebelt - renew it if it is worn or
deteriorated (see Chapter 1).
(b) Ensure the alternator mounting bolts and
nuts are tight.
(c) Inspect the alternator wiring harness and
the electrical connections at the
alternator; they must be in good
condition, and tight.
(d) Check the large main fuses in the engine
compartment (see Chapter 12). If any is
blown, determine the cause, repair the
circuit and renew the fuse (the vehicle
won’t start and/or the accessories won’t
work if the fuse is blown).
(e) Start the engine and check the alternator
for abnormal noises - for example, a
shrieking or squealing sound may indicate
a badly-worn bearing or brush.
(f) Make sure that the battery is fully-charged
- one bad cell in a battery can cause
overcharging by the alternator.
(g) Disconnect the battery leads (negative
first, then positive). Inspect the battery
posts and the lead clamps for corrosion.
Clean them thoroughly if necessary (see
Section 3 and Chapter 1). Reconnect the
lead to the negative terminal.
(h) With the ignition and all accessories
switched off, insert a test light between
the battery negative post and the
disconnected negative lead clamp:
(1) If the test light does not come on, re-
attach the clamp and proceed to the next
step.
(2) If the test light comes on, there is a short
in the electrical system of the vehicle. The
short must be repaired before the
charging system can be checked.
(3) To find the short, disconnect the
alternator wiring harness:
(a) If the light goes out, the alternator is
at fault.
(b) If the light stays on, remove each fuse
until it goes out - this will tell you
which component is short-circuited.
2Using a voltmeter, check the battery
voltage with the engine off. It should be
approximately 12 volts.
3Start the engine and check the battery
voltage again. Increase engine speed until the
voltmeter reading remains steady; it should
now be approximately 13.5 to 14.6 volts.
4Switch on as many electrical accessories
(eg the headlights, heated rear window andheater blower) as possible, and check that the
alternator maintains the regulated voltage at
around 13 to 14 volts. The voltage may drop
and then come back up; it may also be
necessary to increase engine speed slightly,
even if the charging system is working
properly.
5If the voltage reading is greater than the
specified charging voltage, renew the voltage
regulator (see Section 13).
6If the voltmeter reading is less than that
specified, the fault may be due to worn
brushes, weak brush springs, a faulty voltage
regulator, a faulty diode, a severed phase
winding, or worn or damaged slip rings. The
brushes and slip rings may be checked (see
Section 13), but if the fault persists, the
alternator should be renewed or taken to an
auto-electrician for testing and repair.
1Disconnect the battery negative (earth) lead
- see Section 1.
2Remove the plenum chamber (see Chap-
ter 4).
3Unscrew the nuts to disconnect the wiring
from the alternator (see illustration). If
additional working clearance is required, undo
the right-hand of the three screws securing
the wiring “rail” to the rear of the inlet
manifold.
4Jack up and support the front right-hand
corner of the vehicle. Remove the auxiliary
drivebelt and the engine oil filter - place a wad
of rag to soak up the spilled oil (see Chap-
ter 1). Rather than refit a used filter, you are
advised to drain the engine oil, and then to fit
a new filter and refill the engine with clean oil
on reassembly. Where an engine oil cooler is
fitted, it may prove necessary to remove this
as well, to provide the clearance necessary to
remove the alternator (see Chapter 2, Part A).
5Unscrew the two bolts securing the power
steering system pipes to the right-hand side
of the front suspension subframe. With the
front wheels in the straight-ahead position,
disconnect the right-hand track rod end from
the steering knuckle (see Chapter 10).
6Remove the mounting bolts and nuts (one
12 Alternator-
removal and refitting
11 Charging system- testing
10 Charging system - general
information and precautions
Engine electrical systems 5•5
5
12.3 Disconnecting alternator wiring
procarmanuals.com