belt LAND ROVER DISCOVERY 1995 Workshop Manual

ELECTRICAL
1
DESCRIPTION AND OPERATION ELECTRICAL EQUIPMENT
DESCRIPTION
The electrical system is Negative ground, and it is
most important to ensure correct polarity of the
electrical connections at all times. Any incorrect
connections made when reconnecting cables may
cause irreparable damage to the semi-conductor
devices used in the generator and regulator. Incorrect
polarity would also seriously damage any
transistorized equipment such as radio and
tachometer etc.
WARNING: During battery removal or
before carrying out any repairs or
maintenance to electrical components
always disconnect the battery negative lead first.
If the positive lead is disconnected with the
negative lead in place, accidental contact of the
wrench to any grounded metal part could cause a
severe spark, possibly resulting in personal
injury. Upon installation of the battery the positive
lead should be connected first.
GENERATOR
The generator is a three phase, field sensed unit. The
rotor and stator windings produce three phase
alternating current, AC, which is rectified to direct
current, DC. The electronic voltage regulator unit
controls the generator output voltage by high
frequency switching of the rotor field circuit. Use only
the correct Vehicle replacement fan belt. Occasionally
check that the engine and generator pulleys are
accurately aligned.
It is essential that good electrical connections are
maintained at all times. Of particular importance are
those in the charging circuit (including those at the
battery) which should be occasionally inspected to
see that they are clean and tight. In this way any
significant increase in circuit resistance can be
prevented.Do not disconnect battery cables while the engine is
running or damage to the semi-conductor devices
may occur. It is also inadvisable to break or make any
connections in the generator charging and control
circuits while the engine is running.
The electronic voltage regulator employs micro-circuit
techniques resulting in improved performance under
difficult service conditions. The whole assembly is
encapsulated in silicone rubber and housed in an
aluminium heat sink, ensuring complete protection
against the adverse effects of temperature, dust, and
moisture etc.
The regulating voltage is set during manufacture to
give the required regulating voltage range of 14.2±
0.2 volts, and no adjustment is necessary. The only
maintenance needed is the occasional check on
terminal connections and wiping with a clean dry
cloth.
The generator system provides for direct connection
of a charge (ignition) indicator warning light, and
eliminates the need for a field switching relay or
warning light control unit. As the warning lamp is
connected in the charging circuit, lamp failure will
cause loss of charge. Lamp should be checked
regularly and spare carried.
When using rapid charge equipment to re-charge the
battery, the battery must be disconnected from the
vehicle.
NOTE: For description and operation of
electrical circuits see separate publication:
Electrical Troubleshooting Manual.

ELECTRICAL
1
FAULT DIAGNOSIS GENERAL INFORMATION
The electrical fault diagnostic tool on Discovery
vehicles is Testbook. Detailed information of electrical
systems, component locations and circuit diagrams
are covered in the Discovery Electrical
Troubleshooting Manual.
See INTRODUCTION,
Information, Fault Diagnostic Equipment
This section covers checks of the charging and
ignition system.
GENERATOR TESTING
Service repair no - 86.10.01
Charging system check
1.Check battery is in good condition, with an open
circuit voltage of at least 12.6 V. Recharge or
substitute battery to carry out test.
2.Check drive belt condition.
See SECTION 10,
Maintenance, Under Bonnet [Hood]
Maintenance
3.Check battery connections are clean and tight.
4.Check generator connections are clean and
tight.
5.Ensure there is no drain on battery from, for
example, interior, under bonnet [hood] or door
edge lamps.
Generator test
Following instructions refer to use of suitable test
equipment using a carbon pile rheostat.
6.Connect test equipment referring to
manufacturer's instructions.
7.Start engine and run at 3000 rev/min without
accessory load.
8.Rotate carbon pile load control to achieve
greatest output (amps) without allowing voltage
to fall below 12.0 V. A reading in amps, of
generator output, minus 10% to allow for EFI
and Ignition loss, should be obtained.
9.Run engine at 3000 rev/min, switch selector to
regulator test, read voltmeter. A reading of 13.6
to 14.4 V should be obtained.
10.Switch selector to diode/stator test, switch on
headlamps to load generator. Raise engine
speed to 3000 rev/min, read voltmeter, needle
must be within 'OK' range.TESTING IN POSITION
Charging circuit resistance test.
1.Connect a low range voltmeter between
generator terminal marked B+ and positive
terminal of battery.2.Switch on headlamps, start engine. Run engine
at approximately 3000 rev/min. Note voltmeter
reading.
3.Transfer voltmeter connections to frame of
generator and negative terminal of battery, and
again note voltmeter reading.
4.If reading exceeds 0.5 volt on positive side or
0.25 volt on negative side, there is a high
resistance in charging circuit which must be
traced and remedied.

ELECTRICAL
1
ADJUSTMENT IGNITION TIMING
Service repair no - 86.35.15
Adjust
1.It is essential that following procedures are
adhered to. Inaccurate timing can lead to serious
engine damage and additionally create failure to
comply with emission regulations. If timing is
being checked in vehicle, air conditioning
compressor must be disengaged.
2.On initial engine build, or if distributor has been
disturbed for any reason, ignition timing must be
set statically to 6°B.T.D.C.
NOTE: This approximate setting is made
only to ensure that engine may be started.
CAUTION: On no account must engine be
started before this operation is carried out.Equipment required :-
Calibrated Tachometer
Stroboscopic lamp
3.Couple stroboscopic timing lamp and tachometer
to engine following manufacturer's instructions.
4.Disconnect vacuum hose from distributor.
5.Start engine. With no load, and without
exceeding 3,000 rev/min run engine until normal
operating temperature is reached. (Thermostat
open). Check that engine idles within tolerance
specified in data section.
6.Idle speed for timing purposes must not exceed
800 rev/min.
7.Run engine at idle speed and check timing using
stroboscope light on timing marker and pointer.
WARNING: Keep hands and equipment
away from belt.
8.If timing is not as specified, switch off engine.
Loosen distributor clamp bolt and turn distributor
to advance or retard ignition as necessary.
Tighten clamp bolt, start engine and recheck
timing.
WARNING: Personal injury may result if an
attempt is made to adjust distributor whilst
engine is running.
9.Upon completion, switch off engine and retighten
distributor clamping bolt securely. Recheck
timing, to ensure retightening has not disturbed
distributor position.
10.Refit vacuum hose.
11.Disconnect stroboscopic timing lamp and
tachometer from engine.

86ELECTRICAL
34
REPAIR PRINTED CIRCUIT AND WARNING LIGHTS
1. Panel illumination bulbs
2. Transmission oil temperature warning lamp bulb
3. Hazard warning lamp bulb
4. Check engine warning lamp bulb
5. Handbrake/brake fluid warning lamp bulb
6. ABS warning lamp bulb
7. Headlamp main beam warning lamp bulb
8. Trailer direction warning lamp bulb9. Direction indicator warning lamp bulb
10. Air suspension warning lamp bulb
11. Ignition/no charge warning lamp bulb
12. Seat belt warning lamp bulb
13. Not used
14. Traction control warning lamp bulb
15. Diesel heater plug warning lamp bulb (if fitted)
16. Main printed circuit