Test B: Front Radio Control Unit Does Not Respond To NGS Tester
- Turn ignition off. Disconnect front radio control unit 20-pin connector C258 located behind center of instrument panel, on radio. See Figure. Inspect connector for loose, damaged or corroded terminals. Repair as necessary and retest system for normal operation. If connector is okay, reconnect connector. Turn ignition on. Perform data link diagnostic procedure. See DATA LINK DIAGNOSTIC TEST under COMMUNICATION NETWORK DIAGNOSTICS. If NGS tester indicates FCM: NO RESPONSE ON CKT 914 (BUS +), go to next step. If NGS tester does not indicate FCM: NO RESPONSE ON CKT 914 (BUS +), go to step 3).
- Turn ignition off. Disconnect NGS tester. Using an ohmmeter, measure resistance of Tan/Orange wire between terminal No. 3 at front radio control unit connector C258 and terminal No. 2 at Data Link Connector (DLC). See Figure and Fig 1. If resistance is less than 5 ohms, replace front radio control unit and retest system for normal operation. If resistance is 5 ohms or more, repair open Tan/Orange wire between front radio control unit connector and DLC. Retest system for normal operation.
- Turn ignition off. Disconnect NGS tester. Measure resistance of Pink/Light Blue wire between terminal No. 4 at front radio control unit connector C258 and terminal No. 10 at DLC. If resistance is less than 5 ohms, replace front radio control unit and retest system for normal operation. If resistance is 5 ohms or more, repair open in Pink/Light Blue wire between front radio control unit connector and DLC.
Courtesy of FORD MOTOR CO.