Main Relay (Computer/Fuel System): Testing and Inspection

Testing the Main Relay:
- Disconnect one of the harness connectors from a fuel injector.
- With the ignition ON, check for voltage between the red/white wire of the connector and ground. If battery voltage is present, the Main Relay is probably working.

If voltage is present at the fuel injector connector, check the wiring and voltage to the Main Relay connector:

View - LH Front Of Engine Compartment:

- Remove the Main Relay from the Power Distribution box. [1]

Connector - Main Relay:

- Check for voltage between terminal 30 and ground. If battery voltage is not present, check the large red wire between the relay socket and the battery. If battery voltage is present, proceed to next step.
- With the ignition ON, check for voltage between terminal 86 and ground. If battery voltage is present and no faults are found in either the wiring or connectors, the Main Relay is faulty and should be replaced. [2]
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[1]: Due to changes during production, the Main Relay may be located in an adjacent position. To check if the Main Relay has been correctly identified, inspect the wires leading to the relay socket. There should be two large (4 mm) wires leading to the socket for the Main Relay.

[2]: Power is supplied to terminal 86 of the Main Relay from the On-Board Computer relay box.