Test B: Front Radio Control Unit Does Not Respond To NGS Tester
WARNING: This page is about a different car, the 2001 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Front radio control unit may also be referred to as Audio Control Module (ACM).
- Turn ignition switch to LOCK position. Disconnect front radio control unit 20-pin harness connector C258. Front radio control module is located behind center of instrument panel, on radio. See Figure. Inspect front radio control unit harness connector C258 for loose, damaged or corroded terminals. Repair as necessary and retest system for normal operation. If harness connector is okay, reconnect front radio control unit harness connector C258. Connect New Generation Star (NGS) tester to Data Link Connector (DLC). DLC is located below left side of instrument panel, to right of steering column. Turn ignition switch to RUN position and perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST under SELF-DIAGNOSTIC SYSTEM. If NGS tester indicates ACM: NO RESPONSE ON CKT 914 (BUS +), go to next step. If NGS tester indicates ACM: NO RESPONSE ON CKT 915 (BUS -), go to step 3.
- Turn ignition switch to LOCK position. Disconnect NGS tester. Disconnect front radio control unit 20-pin harness connector C258. Measure resistance in Tan/Orange between front radio control unit harness connector C258 terminal No. 3 wire and DLC terminal No. 2. See Figure and Fig 1 . If resistance is 5 ohms or more, repair open in Tan/Orange wire between front radio control unit and DLC. If resistance is 5 ohms or less, replace front radio control unit. Restore electrical connections and retest system for normal operation.
- Turn ignition switch to LOCK position. Disconnect NGS tester. Disconnect front radio control unit 20-pin harness connector C258. Measure resistance in Pink/Light Blue wire between front radio control unit harness connector C258 terminal No. 4 and DLC terminal No. 10. See Figure and Fig 1 . If resistance is 5 ohms or more, repair open in Pink/Light Blue wire between front radio control unit and DLC. If resistance is 5 ohms or less, replace front radio control unit. Restore electrical connections and retest system for normal operation.