Main Relay Test

Fault Symptom.
Engine fails to start.





Diagnostic Procedure.
1. Check the performance of the main relay
- Unplug the IAC valve's 3-pin connector
- Ignition switch in the ON position.
- Connect the test lamp to pin 2 and battery negative (B-).

The test lamp should light up.

Test lamp on?

YES: The main relay is OK
NO: Continue with point 2.





2. Check the power Supply for the main relay circuit
- Unplug the main relay from its socket.
- Turn the ignition switch to the ON position.
- Connect the test lamp to:
^ pin 30 of the relay socket and a good grounding point
^ pin 86 of the relay socket and a good grounding point.

Test lamp on?

YES: Continue with point 3.
NO: Continue fault diagnosis in the Electrical system, wiring diagrams.





3. Check the relay output
- Unplug the IAC valve's 3-pin connector.
- Connect the test lamp to pin 2 and battery negative (B-).
- Connect a jumper lead between pins 30 and 87 of the relay socket.
The test lamp should light up.

Test lamp on?

YES: Continue with point 4.
NO: Check the lead for continuity/shorting to ground and repair or replace it if necessary.

4. Check the control module's output
- Connect the test lamp to pins 30 and 85 of the relay socket.
- Turn the ignition switch to the ON position.

The test lamp should light up.

Test lamp on?

YES: Change the main relay.
NO: Check the lead between pin 85 of the relay and pin 27 of the control module (via pin 15 of connector H70-1) for continuity. If the lead is OK, continue as described at "Before Replacing a Control Module". Component Tests and General Diagnostics