Main relay
Symptom of fault
Engine will not start
Diagnostic procedure
1. Check the operation of the main relay
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Connect an ISAT scan tool.
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Ignition switch in ON position.
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The main relay is activated for 10 seconds at a frequency of 1 Hz. If a longer
activation time is required, the command will have to be repeated.
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Listen for the sound of the main
relay and idle air control valve working.
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They should both click at a frequency of 1 Hz (once a second).
Does only the main relay click?
Continue with point 2.
Neither the main relay nor the idle air control valve clicks. Continue with point
5.
2. Check fuse 16B
Is the fuse OK?
Continue with point 3.
Change the fuse and continue with point 3.
3. Forcibly supply the main relay with power
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Connect a jumper lead between
fuses 4 and 16B.
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Does the idle air control valve click?
Continue with point 4.
Repair or replace the lead between fuse 16B and crimped connection J67.
4. Check the main relay
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Connect a jumper lead between
pins 30 and 87 on the relay holder.
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The idle air control valve should click.
Does the valve click?
Change the main relay.
Check the lead between pin 87 and fuse 16B and the lead between pin 30 and
battery positive (B+).
5. Check the main relay
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Connect the test lamp to pins 85
and 86 of the relay holder.
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Ignition switch in ON position.
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The test lamp should flash.
Does the test lamp flash?
Change the main relay.
Proceed to point 6.
6. Check the main relay's power
supply
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Connect the test lamp to pin 86 of
the relay holder and a good grounding point.
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The test lamp should light up.
Is the test lamp on?
Continue with point 7.
Check the lead between pin 86 and battery positive (B+). Repair or replace it if
necessary.
7. Check the main relay's connection to ground
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Check and if necessary repair or
replace the lead between pin 85 of the relay holder and pin 31 of the control module.
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Is the lead OK?
Proceed to
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Rectify the fault.
