Test C: No Communication With Generic Electronic Module
WARNING: This page is about a different car, the 2002 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Perform all voltage and resistance tests using a Digital Volt-Ohm Meter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.
- Turn ignition switch to RUN position. Measure voltage between ground and input side of Central Junction Box (CJB) fuse No. 39 (5-amp). CJB is located behind left side of instrument panel. See Figure. If battery voltage exists at both terminals, go to next step. If battery voltage does not exist, repair fuse circuit as necessary. For POWER DISTRIBUTION circuit identification, see WIRING DIAGRAMS . After repair, test system for normal operation.
- Turn ignition switch to LOCK position. Ensure fuse No. 32 (5-amp) is re-installed. Disconnect Generic Electronic Module (GEM) 4-pin harness connector C201b. See Fig 1. GEM is located behind left side of instrument panel, next to CJB. See Figure. Turn ignition switch to RUN position. Measure voltage between ground and GEM harness connector C201b terminal No. 1 (White/Yellow wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open circuit in White/Yellow wire between GEM and fuse No. 39. For POWER DISTRIBUTION circuit identification, see WIRING DIAGRAMS . After repair, test system for normal operation.
- Turn ignition switch to LOCK position. Measure resistance between ground and GEM harness connector C201b terminal No. 2 (Black/White wire). See Fig 1. If resistance is 5 ohms or less, repair module communication concern. See MODULE COMMUNICATIONS NETWORK - MUSTANG article. If resistance is more than 5 ohms, repair open circuit in Black/White wire between GEM and ground point G204. Ground G204 point is located behind center of instrument panel. See Figure. For GROUND DISTRIBUTION circuit identification, see WIRING DIAGRAMS . After repair, test system for normal operation.
- With ignition switch to LOCK position. Measure resistance between GEM connector C201b terminal No. 1 and CJB fuse No. 39 (5-amp) (White/Yellow wire). See Fig 1. If resistance is more than 5 ohms, repair open circuit in White/Yellow wire between GEM and CJB. If resistance is 5 ohms or less, repair power voltage supply circuit to CJB fuse No. 39 (5-amp). For POWER DISTRIBUTION circuit identification, see WIRING DIAGRAMS . After repair, test system for normal operation.