Test E: No Communication With Gem
- Check Maxi-Fuse
- Using ohmmeter, check condition of maxi-fuse No. 1 (50-amp) in engine compartment fuse/relay 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 fuse/relay box and instrument panel fuse block for short to ground. Repair circuit as necessary.
- Check Fuse
- Using 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. Clear DTCs and retest system operation.
- Check White/Yellow Wire For Voltage
- Turn ignition off. Disconnect 18-pin GEM/CTM connector C224 (located behind center of instrument panel). Using a voltmeter, check voltage between ground and 18-pin GEM/CTM connector C224 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 26-pin GEM/CTM connector C221 (located behind center of instrument panel). Using an ohmmeter, check resistance between ground and 26-pin GEM/CTM connector C221 terminal No. 14 (Black/White wire). See Fig 2. Check resistance between ground and 26-pin GEM/CTM connector C221 terminal No. 26 (Black/White wire). If both resistance readings are less than 5 ohms, go to next step. If either resistance reading is 5 ohms or more, repair open in appropriate Black/White wire(s). Clear DTCs and retest system operation.
- Check Light Green/Black Or Black Wire For Open
- Using an ohmmeter, check resistance between ground and 18-pin GEM/CTM connector C224 terminal No. 18 (Light Green/Black or Black wire). See Figure. If resistance is less than 5 ohms, replace GEM. Clear DTCs and retest system operation. If resistance is 5 ohms or more, repair open in Light Green/Black or Black wire. Clear DTCs and retest system operation.
Courtesy of FORD MOTOR CO.
Courtesy of FORD MOTOR CO.