DAF LF45, LF55 Series. Manual — part 336
5
LF45/55 series
Alternator
DIAGNOSTICS
2-1
2. ALTERNATOR
2.1 FAULT-FINDING TABLE
SYMPTOM: ALTERNATOR NOT PRODUCING POWER WHEN IDLING
Possible cause
Remedy
Open circuit in connection 15 on alternator
Repair connection 15
Connection 15 on alternator short-circuited to
earth
Repair connection 15
Internal defect
Replace regulator
SYMPTOM: ALTERNATOR WARNING (YELLOW)
Possible cause
Remedy
Open circuit in “S” connection
Measure the regulated alternator voltage with as
many consumers as possible switched on and
with the engine turning above idling speed
Open circuit in “L” connection
Check/repair wiring
Open circuit in connection 15
Increase the engine speed to approx. 1500 rpm.
If voltage is now present, check connection 15
on the alternator
Voltage difference between “B+” and
“S” connections is greater than 2.5 V
Check all contacts between alternator and B+
(contact resistors)
Internal battery resistance too high
Voltage too low < 16 V
Check alternator drive.
Check wiring on contact resistors
SYMPTOM: ALTERNATOR VOLTAGE HIGH (RED)
Possible cause
Remedy
Voltage too high > 31 V
Measure voltage
Internal defect
Replace regulator/alternator
1
200440
5
DIAGNOSTICS
Alternator
LF45/55 series
2-2
1
200440
5
LF45/55 series
Fault finding
DIAGNOSTICS
3-1
3. FAULT FINDING
The following test equipment and tools can be
used to trace faults.
1. The best instrument for this is a digital
multimeter. This instrument can be used to
measure voltages, currents and resistances
without reading errors and it can be used to
trace virtually any faults.
2. The “Multimeter” function of DAVIE XD can
be used to carry out all the measurements
that can be made with an ordinary, separate
multimeter.
3. Many, but not all, faults are easily traced by
means of warning lamps. Failures caused
by poor earthing cannot normally be
detected by a warning lamp or buzzer.
The most frequently occurring faults are:
a.
short circuit
b.
open circuits
c.
earthing problems (poor earthing due to
corrosion).
1
200440
5
DIAGNOSTICS
Fault finding
LF45/55 series
3-2
3.1 SHORT CIRCUITS
A short circuit is caused by a positive wire
shorting somewhere to earth. This can generate
a very high current. In most cases this will cause
a fuse to blow.
To remedy this failure, use a test lamp of
approximately 70 W. First check the diagram to
see which consumers are connected to the fuse
in question and then switch them all off.
Remove the fuse and connect the test lamp in
its place. Now switch each of the consumers on
and off one by one. If the lamp comes on very
brightly when a consumer is switched on, the
fault is almost certainly in the wiring of that
consumer. Now check the diagram to see via
which connectors the consumer is connected.
Now disconnect the first wiring connection (as
seen from the fuse).
If the lamp is still bright, the fault is between the
fuse and this wiring connection.
If, however, the lamp goes out, the fault is
somewhere further on in the wiring.
Now reconnect the connectors and disconnect
the next wiring connection. If the lamp is still
bright, the failure is between these two wiring
connections.
However, if the lamp goes out again, the
fault-finding procedure must be continued.
The faulty wiring section can be found in this
way.
W 5 03 013
1
200440
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст