Code 6-4: Rear Fail-Safe Relay Circuit
- Remove rear fail-safe relay. Test relay and replace if necessary. See RELAY TEST under DIAGNOSIS & TESTING. If relay is okay, turn ignition switch to ON position.
- Measure voltage between Black/Yellow wire terminal of fail-safe relay and ground. If battery voltage is not present, repair open Black/Yellow wire between fuse and fail-safe relay.
- If battery voltage is present, turn ignition switch to OFF position. Disconnect 10-pin connector from solenoid. Using DVOM, check continuity between Blue/Black wire terminal of fail-safe relay and ground. If continuity does not exist, go to next step. If continuity exists, repair shorted Blue/Black wire between solenoid and rear fail-safe relay.
- Remove front fail-safe relay. Check continuity between Brown/White wire terminal of solenoid and ground. If continuity does not exist, go to next step. If continuity exists, solenoid is defective. Replace modulator.
- Disconnect 18-pin and 12-pin connectors from control unit. Check continuity of following wires between control unit and ground: Red/White wire and Yellow/White wire. If continuity does not exist, go to next step. If continuity exists, repair shorted wire(s) between solenoid and control unit connector.
- Check continuity between 18-pin connector Yellow/Green wire terminal and ground. If continuity does not exist, go to next step. If continuity exists, repair shorted Yellow/Green wire between control unit and rear fail-safe relay.
- Reinstall rear fail-safe relay. Turn ignition switch to ON position. Measure voltage between Yellow/Green wire terminal of control unit connector and ground. If battery voltage is not present, repair open Yellow/Green wire between rear fail-safe relay and control unit. If battery voltage exists, check for loose control unit connectors. If connectors are okay, install a known-good control unit and retest.