Volvo TAD650VE, Руководство по ремонту

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Repair instructions Group 30: Electrical system
24
Fault tracing of cables and
connectors
Special tools: 9812519, 999 8482
Check all connectors visually
Check the following:
l
Look for oxidation which can impair contact in con-
nectors.
l Check that terminals are undamaged, that they are
correctly inserted into their connectors, and that
the cable is correctly terminated in the terminal.
●
Check that there is good mechanical contact in the
connector. Use a loose pin to check this.
IMPORTANT! The multi-pin connectors for
the engine control unit must only be checked
with gauge 999 8482.
●
Carefully insert gauge 999 8482 into the multi-pin
connector. Pull and push the connector in and out
a few times and feel whether the terminal socket
grasps the tool. If the terminal socket does not
grasp, or if it feels slack, the connection pins
should be changed. Please refer to ”Joining electri-
cal cables for multi-connector” Check the second-
ary locking in the connector.
●
If possible, shake the cables and pull the connec-
tors during measurement to discover whether the
cable harness is damaged.
●
Check that the cables are not damaged. Avoid
clamping cables in tight bends close to the con-
nector.
●
Check the function of the secondary locking.
Contact problems
Intermittent contact or temporary recurring faults can
be difficult to fault trace, and are frequently caused by
oxidation, vibration or poorly terminated cables.
Wear can also cause faults. For this reason, avoid dis-
connecting a connector unless it is necessary.
Other contact problems can be caused by damage to
pins, sockets and connectors etc.
Shake cables and pull connectors during measure-
ment, to find where the cable is damaged.
Contact resistance and oxidation
Resistance in connectors, cables and junctions
should be close to 0
Ω.
A certain amount of resistance
will occur, however, because of oxidation in connec-
tors.
If this resistance is too great, malfunctions occur. The
amount of resistance that can be tolerated before mal-
functions occur varies, depending on the load in the
circuit.
Open circuit
Possible reasons for faults could be chafed or broken
cables, or connectors which have come undone.
Use the wiring schedule to check the cable harnesses
which are relevant to the function. Start off with the
most probable cable harness in the circuit.
Check the following:
●
Disconnect the relevant connector at each end of
the cable harness.
●
Use multimeter 9812519 to measure the resis-
tance between the ends of the cable.
Nominal value close to 0
Ω.
●
If possible, shake the cables and pull the connec-
tors during measurement to discover whether the
cable harness is damaged.
●
Check the next cable harness in the wiring sched-
ule if no fault has been found.