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 on. Measure voltage between Yellow/Black wire terminal of fail-safe relay and ground.
- If battery voltage does not exist, repair open Yellow/Black wire between fuse No. 1 (in underdash fuse/relay box) and rear fail-safe relay. If battery voltage exists, turn ignition off. Disconnect solenoid connector, located on right side of engine compartment, near shock tower.
- Using DVOM, check for 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.
- Check continuity between Brown/White wire terminal of solenoid connector and ground. If continuity does not exist, go to next step. If continuity exists, solenoid is defective. Replace modulator.
- Disconnect 12-pin (models without traction control) or 14-pin (models with traction control) connector. Check continuity of Red/White wire and Yellow/White wire between control unit and ground. If continuity does not exist, go to next step. If continuity exists, repair shorted wire(s).
- Remove front fail-safe relay. Disconnect 18-pin (without traction control) or 20-pin (with traction control) connector. Check continuity between Yellow/Green wire terminal and ground. If continuity exists, repair shorted Yellow/Green wire between control unit connector and rear fail-safe relay. If continuity does not exist, go to next step.
- Reinstall rear fail-safe relay. Turn ignition on. Measure voltage between Yellow/Green wire terminal and ground. If battery voltage does not exist, repair open Yellow/Green wire between control unit and rear fail-safe relay. If battery voltage exists, check for loose control unit connectors. If connectors are okay, install a known-good control unit and retest.