Test A: No Communication With Generic Electronic Module
WARNING: This page is about a different car, the 2002 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
- Turn ignition switch to LOCK position. Connect New Generation Star (NGS) tester to Data Link Connector (DLC). DLC is located below driver's side of instrument panel, right of steering column. Depress clutch pedal (if equipped). Using NGS tester, monitor IGN_GEM PID while rotating ignition switch through all positions. If PID values match ignition switch positions, go to next step. If PID values do not match with ignition switch positions, repair open in appropriate wire between ignition switch and battery junction box. See POWER DISTRIBUTION in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Clear DTCs and retest system.
- Disconnect central junction box Black harness connector C270b. See Fig 1. Measure voltage between ground and central junction box Black harness connector C270b terminal No. 11 (Tan/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Tan/Black wire between battery junction box and central junction box. See POWER DISTRIBUTION in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Clear DTCs and retest system.
- Disconnect GEM 18-pin internal connector C270d. GEM is mounted on back of central junction box. Reconnect central junction box harness connector C270b. Turn ignition switch to RUN position. Measure voltage between ground and GEM internal connector C270d terminals No. 4 and 16 (component side). See Fig 1. If battery voltage exists, go to next step. If battery voltage does not exist, replace central junction box. Clear DTCs and retest system.
- Turn ignition switch to LOCK position. Disconnect Gray GEM 26-pin harness connector C201a. Measure resistance between ground and GEM harness connector C201a terminal No. 26 (Black/Light Blue wire). See Fig 2. If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Black/Light Blue wire between GEM and ground. Ground is located behind left kick panel. Clear DTCs and retest system.
- Measure resistance between ground and GEM harness connector C201a terminal No. 14 (Black/Light Blue wire). See Fig 2. If resistance is 5 ohms or less, fault is in module communications network. See MODULE COMMUNICATIONS NETWORK - F150 PICKUP article to continue diagnosis. If resistance is more than 5 ohms, repair open in Black/Light Blue wire between GEM and ground. Ground is located behind left kick panel. Clear DTCs and retest system.