Test J: No Scan Tool Communication With Gem
NOTE:
After all repairs, clear DTCs and retest system.
- Check battery junction box maxi-fuse No. 1 (50-amp). If fuse is okay, go to next step. If fuse is not okay, replace fuse. Clear DTCs and retest system. If fuse fails again, check for short to power in Tan/Black wire between battery junction box and fuse junction panel. Repair circuit as necessary.
- Check fuse junction panel fuse No. 25 (7.5-amp). If fuse is okay, go to next step. If fuse is not okay, replace fuse. Clear DTCs and retest system operation. If fuse fails again, check for short to ground White/Yellow wire between fuse junction panel and GEM. Repair circuit as necessary.
- Measure voltage between fuse junction panel fuse No. 25 (7.5-amp) fuse holder (input side) and ground. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair Tan/Black wire. See POWER DISTRIBUTION article in WIRING DIAGRAMS.
- Turn ignition off. Disconnect negative battery terminal. Disconnect GEM 18-pin connector C283. Connect negative battery cable. Measure voltage between GEM connector C283 terminal No. 11 (White/Yellow wire) and ground. See Figure . If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair White/Yellow wire between fuse junction panel and GEM.
- Turn ignition off. Disconnect negative battery terminal. Disconnect GEM 26-pin connector C280. Connect negative battery cable. Measure resistance between GEM connector C280 terminal No. 14 (Black/White wire) and ground. See Fig 1 . Measure resistance between terminal No. 26 (Black/White wire) and ground. If each resistance is less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open in appropriate Black/White wire(s) between GEM connector C280 and ground. Ground point is located left front engine compartment near radiator.
- Measure resistance between GEM 18-pin connector C283 (Black wire) terminal No. 18 and ground. See Figure . If resistance is less than 5 ohms, problem is in module communications network. See MODULE COMMUNICATIONS NETWORK - EXPLORER & MOUNTAINEER article. If resistance is 5 ohms or more, repair open in Black wire.