Test J: No Communication With Gem
- Check Maxi-Fuse
- Using an ohmmeter, check condition of maxi-fuse No. 1 (50-amp) in engine compartment power distribution box. 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 Tan/Black wire between engine compartment power distribution box and instrument panel fuse block for short to ground. Repair circuit as necessary.
- Check Fuse
- Using an ohmmeter, check condition of instrument panel fuse block 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 White/Yellow wire between instrument panel fuse block and GEM/CTM for short to ground. Repair circuit as necessary.
- Check Tan/Black Wire For Voltage
- Using a voltmeter, check voltage between ground and instrument panel fuse block fuse No. 25 (7.5-amp) terminal No. 2. See Fig 1
. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair Tan/Black wire between engine compartment power distribution box and instrument panel fuse block. Clear DTCs and retest system operation.
- Check White/Yellow Wire For Voltage
- Turn ignition off. Disconnect GEM/CTM 18-pin connector C224 (located behind center of instrument panel). Using a voltmeter, check voltage between ground and GEM/CTM 18-pin connector C283 terminal No. 11 (White/Yellow wire). 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 instrument panel fuse block and GEM/CTM. Clear DTCs and retest system operation.
- Check Black/White Wire For Open
- Disconnect GEM/CTM 26-pin connector C280. Using an ohmmeter, check resistance between ground and GEM/CTM 26-pin connector C280 terminal No. 14 (Black/White wire). See Fig 2
. Check resistance between ground and GEM/CTM 26-pin connector C280 terminal No. 26 (Black/White wire). If both resistance readings are less than 5 ohms, see MODULE COMMUNICATIONS NETWORK article to continue diagnosis. If either resistance reading is 5 ohms or more, repair open in appropriate Black/White wire. Clear DTCs and retest system operation.
Courtesy of FORD MOTOR CO.
Courtesy of FORD MOTOR CO.