Main Relay Harness Test

Main Relay Harness Testing.

1. Keep the ignition switch in the OFF position.

2. Disconnect the main relay connector.

Main Relay Test Pins No. 2 and No.1:

3. Check for continuity between the BLK wire (pin 2) in the connector and body ground.

If there is continuity, go to step 4.
If there is no continuity, repair open in BLK wire.

4. Attach the positive probe of the voltmeter to the YEL/BLU wire (pin 1) and the negative probe to the BLK wire (pin 2). Battery voltage should be available.

If there is no voltage, check the ECU fuse (main fuse box), and the wiring between the main relay and the ECU fuse (10A).

Main Relay Test Pins No.2 and No.5:

5. Attach the positive probe of the voltmeter to the BLK/YEL wire (pin 5) and the negative probe to the BLK wire (pin 2).

6. Turn the ignition switch ON. Battery voltage should be available.

If there is no voltage, check No. 2 fuse, the wiring from the ignition switch to the fuse box, and the wiring from the fuse box to the main relay.

Main Relay Test Pins No. 2 and No. 6:

7. Attach the positive probe of the voltmeter to the BLK/GRN (M/T) or the BLU/RED (A/T) wire (pin 6), and the negative probe to the BLK wire (pin 2).

8. Turn the ignition switch to START position. Approximately 10 volts should be available.

If there is no voltage, check the No. 9 (7.5 A) fuse, the wiring between the ignition switch and fuse box, and from the fuse box to the main relay.

Main Relay Test Pins No. 5 and No. 7:

9. Connect a jumper wire between the BLK/YEL wire (pin 5) and the YEL wire (pin 7).

10. Turn the ignition switch ON. The fuel pump should work.

If the fuel pump does not work, check the wiring between the main relay and the fuel pump, and the wiring from the fuel pump to the ground (BLK wire).