Test I: No Communication With Gem/CTM Module
- Check maxi-fuse No. 1 (60-amp) in Battery Junction Box (BJB). If fuse is okay, go to next step. If maxi-fuse No. 1 is blown, replace fuse and recheck system operation. If fuse blows again, check for short to ground in Tan/Black wire between BJB and CJB. Repair as necessary. Recheck system operation.
- Check fuse No. 25 (7.5-amp) in Central Junction Box (CJB). If fuse No. 25 is blown, replace fuse and recheck system operation. If fuse blows again, check for short to ground in White/Yellow wire between CJB, PATS module, instrument cluster or GEM/CTM. Repair as necessary.
- Measure voltage between ground and fuse junction panel fuse No. 25 terminal No. 2 (Tan/Black wire). See Fig 1. If more than 10 volts exist, go to next step. If 10 volts or less exist, repair open in Tan/Black wire. Clear DTCs and recheck system operation.
Courtesy of FORD MOTOR CO.
- Turn ignition switch to LOCK position. Disconnect GEM/CTM 18-pin harness connector C283. Measure voltage between ground and GEM/CTM harness connector C283 terminal No. 11 (White/Yellow wire). See Fig 2. If more than 10 volts exist, go to next step. If 10 volts or less exist, repair open in White/Yellow wire between CJB and GEM/CTM. Clear DTCs and recheck system operation.
- Disconnect GEM/CTM 26-pin harness connector C280. Measure resistance between ground and GEM/CTM harness connector terminals No. 14 and 26 (Black/White wires) individually. See . If resistance is less than 5 ohms in both measurements, diagnose network concern. See MODULE COMMUNICATIONS NETWORK - EXPLORER & MOUNTAINEER article. If resistance is more than 5 ohms, repair open in Black/White wire(s). Clear DTCs and recheck system operation.
Courtesy of FORD MOTOR CO.