Test A: No Communication With Gem
NOTE:
After repair, clear Diagnostic Trouble Codes (DTC) and retest system.
- Turn ignition switch to LOCK position. Connect New Generation Star (NGS) tester to Data Link Connector (DLC). DLC is located below center of instrument panel, right of steering column. Using NGS tester, observe Generic Electronic Module (GEM) PIDs IGN_A, IGN_R, IGN_S and IGN_O/L while turning ignition switch through all positions. If PID values agree with ignition switch positions, go to next step. If PID values do not agree with ignition switch positions, repair appropriate ignition switch circuit(s). See POWER DISTRIBUTION in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- Turn ignition switch to LOCK position. Disconnect central junction box 34-pin harness connector C243. Central junction box is located under left side of instrument panel. Measure voltage between ground and central junction box harness connector C243 terminal No. 11 (Tan/Black wire). See Fig 1. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Tan/Black wire between central junction box and battery junction box. See POWER DISTRIBUTION in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- Disconnect GEM from central junction box 18-pin harness connector C267. GEM is located on backside of central junction box. Connect central junction box harness connector C243. Measure voltage between ground and central junction box harness connector C267 terminal No. 4 (component side). Measure voltage between ground and central junction box connector C267 terminal No. 16. See Fig 1. If battery voltage exists at both terminals, go to next step. If battery voltage does not exist at either terminal, replace central junction box. See CENTRAL JUNCTION BOX under REMOVAL & INSTALLATION.
- Disconnect GEM 26-pin harness connector C239. GEM is located on backside of central junction box. Measure resistance between ground and GEM harness connector C239 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 or high resistance in Black/Light Blue wire between GEM and ground. Ground point is located behind left kick panel. See WIRING DIAGRAMS .
- Measure resistance between ground and GEM harness connector C239 terminal No. 14 (Black/Light Blue wire). If resistance is 5 ohms or less, repair module communications concern. See MODULE COMMUNICATIONS NETWORK - EXPEDITION & NAVIGATOR article. If resistance is more than 5 ohms, repair open or high resistance in Black/Light Blue wire between GEM and ground. Ground point is located behind left kick panel. See WIRING DIAGRAMS .