DIESEL EQUIPMENT
Pre-post-heating unit
13
FAULT FINDING
1. The pre-heating warning light does not operate
TEST SOLUTION
Earth the warning light output of connector (C) using
a 2 A fuse when the ignition is turned on (track B3).
• The fuse blows.
• The warning light does not illuminate.
• The warning light does illuminate.The warning light wiring in the instrument panel is in
short circuit. Repair the wiring.
The bulb is blown or the wiring is faulty.
Replace the bulb or repair the wiring.
Check:
- + battery on connector (A),
- + after ignition on connector (C),
- battery earth on connector (C).
If the feed is correct, replace the pre-post-heating
unit.
2. The pre-heating warning light only operates for a fraction of a second when the ignition is turned on.
TEST SOLUTION
Disconnect connector (B) and test the pre-heating:
• The warning light illuminates and there is a
voltage at the connector outputs (B).
• The warning light illuminates and there is no
voltage at the connector outputs (B).
• The pre-heating warning light illuminates for a
fraction of a second only.Check the plugs circuit. If it is correct, check and
replace the faulty plug(s).
Replace the pre-post-heating unit.
Check the before ignition feed to the pre-heating
unit.
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STARTING - CHARGING
Alternator
16
OPERATION - FAULT FINDING
These vehicles are fitted with alternators with in-
ternal ventilation, an integral regulator and a
warning light on the instrument panel which ope-
rates as follows :
- when the ignition is turned on, the warning
light illuminates,
- when the engine starts, the warning light ex-
tinguishes,
- if the warning light illuminates again when
the engine is running, there is a "charging"
fault.
LOOKING FOR FAULTS
The warning light does not illuminate when the
ignition is turned on.
Check:
- the electrical connections are correct,
- the bulb is not blown (to do this, earth the cir-
cuit; the bulb should illuminate).
The warning light illuminates when the engine is
running
There is a charging fault which could be due to:
- the alternator drive belt being broken or the
charging cable being cut,
- internal damage to the alternator (rotor, sta-
tor, diodes or brushes),
- regulator fault,
- an excess voltage.The customer complains of a charging fault and
the warning light operates correctly.
If the regulated voltage is less than 13.5 V, check
the alternator. The fault could be caused by:
- a destroyed diode,
- a cut phase,
- track contamination or wear.
Checking the voltage
Connect a voltmeter across the battery terminals
and read the battery voltage.
Start the engine and increase the engine speed
until the voltmeter needle stabilises at the
regulated voltage.
This voltage should be between 13.5 V and 14.8 V.
Connect as many consumers as possible, the
regulated voltage should remains between 13.5 V
and 14.8 V.
IMPORTANT: if arc welding is carried out on the
vehicle, the battery and the regulator must be
disconnected.
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