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

Inspection Using Scan Tool

Harness Inspection Using Voltmeter




Step 1 of 5




Step 2 of 5




Step 3 of 5




Step 4 of 5




Step 5 of 5

Relay Inspection Using Voltmeter




1. Remove the Multiport Fuel Injection (MFI) relay.




2. Using jumper wires, connect terminal (10) of the MFI relay to the positive battery terminal and connect terminal (8) of the relay to the negative battery terminal.

CAUTION: When connecting the jumper wires, be careful not to connect them to the wrong terminals, since this could damage the relay.

3. Measure the voltage at terminal (4) and terminal (5) of the MFI relay while connecting and disconnecting the jumper wire to the negative battery terminal.




You should get these results.




4. Using jumper wires, connect terminal (9) of the MFI relay to the positive battery terminal and connect terminal (6) of the relay to the negative battery terminal.
5. Check for continuity between terminal (2) and terminal (3) of the MFI relay while connecting and disconnecting the jumper wire and the negative battery terminal.




6. Using jumper wires, connect terminal (3) of the MFI relay to the positive battery terminal and connect terminal (7) of the relay to the negative battery terminal.
7. Measure the voltage at terminal (2) of the MFI relay while connecting and disconnecting the jumper wire to the negative battery terminal.

Jumper wire connected: B+
Jumper wire disconnected: 0 Volts

8. Replace the MFI relay if it is defective.