Code 6-4, Rear Fail-Safe Relay Circuit

Remove and test rear fail-safe relay. See RELAY TEST under COMPONENT TESTS. Replace relay if it is defective. If relay is okay, disconnect 10-pin connector from solenoids and turn ignition switch to ON position. Connector is located on right side of engine compartment, near shock tower.
Check Black/Yellow terminal of fail-safe relay and ground. If battery voltage is not present, repair open in Black/Yellow wire between fuse and fail-safe relay.
If battery voltage is present, turn ignition switch to OFF position. Using DVOM, check for continuity between Blue/Black wire of fail-safe relay and ground. If continuity does not exist, go to next step. If continuity exists, repair short in Blue/Black wire between solenoid and rear fail-safe relay.
Check for continuity at solenoid connector (solenoid side) between Brown/White wire and ground. If continuity does not exist, go to next step. If continuity exists, solenoid is defective.
Disconnect 18-pin and 12-pin connectors from control unit. Check for continuity at 12-pin connector between Red/White wire and ground and between Yellow/White wire and ground. If continuity does not exist in both wires, go to next step. If continuity exists in either wire, repair short in wire having continuity between solenoid and control unit connector.
Check for continuity at 18-pin connector between Yellow/Green wire and ground. If continuity exists, repair short in Yellow/Green wire between control unit connector and front fail-safe relay.
If continuity does not exist, turn ignition switch to ON position. Check for battery voltage between Yellow/Green wire in control unit connector and ground. If battery voltage is not present, repair 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.