Test A - No Communication With Generic Electronic Module

1. To check circuit No. 785 (Black/Light Green wire) for power, disconnect GEM connector C233. See Fig 1 and Fig 2 . Measure voltage from ground to GEM connector C233, pin No. 13 (Black/Light Green wire). If battery voltage is present, go to step 5). If battery voltage is absent, go to next step.
2. To check circuit No. 785 (Black/Light Green wire) for short to ground, remove fuse No. 19 from fuse junction panel. See Figure and Figure . Measure resistance from ground to GEM connector C233, pin No. 1 3 (Black/Light Green wire). See Fig 1 and Fig 2 . If resistance is less than 10 k/ohms, repair circuit No. 785 (Black/Light Green wire) for short to ground. Replace fuse No. 19 and retest system. If resistance is more than 10 k/ohms, go to next step.
3. To check power supply to fuse No. 19, remove fuse No. 19 from fuse panel. Measure voltage at fuse No. 19 input cavity. If battery voltage is present, go to next step. If battery voltage is absent, repair electrical supply to fuse No. 19 and retest system.
4. To check circuit No. 785 (Black/Light Green wire) for open, measure resistance between output cavity of fuse No. 19 and GEM connector C233, pin No. 13 (Black/Light Green wire). If resistance is 5 ohms or less, replace fuse No. 19 and retest system. If resistance is more than 5 ohms, repair circuit No. 785 (Black/Light Green wire) for open and retest system. See Fig 1 and Fig 2 .
5. To check circuit No. 489 (Pink/Black wire) for power, disconnect GEM connector C234. See Fig 1 and Fig 2 . Measure voltage from ground to GEM connector C234, pin No. 22 (Pink/Black wire). If battery voltage is present, go to step 9). If battery voltage is absent, go to next step.
6. To check circuit No. 489 (Pink/Black wire) for short to ground, remove fuse No. 21 from fuse panel. See Fig 1 and Fig 2 . Measure resistance between ground and GEM connector C234 (Pink/Black wire). If resistance is less than 10 k/ohms, repair circuit No. 489 (Pink/Black wire) for short to ground. Replace fuse No. 21 and retest system. If resistance is more than 10 k/ohms, go to next step.
7. To check power supply to fuse No. 21, remove fuse No. 21 from fuse panel. See Fig 1 and Fig 2 . Measure voltage from ground to fuse No. 21 input cavity. If battery voltage is present, go to next step. If battery voltage is absent, repair electrical supply to fuse No. 21, replace fuse and retest system.
8. To check circuit No. 489 (Pink/Black wire) for open, measure resistance between GEM connector C234, pin No. 22 and output cavity of fuse No. 22. If resistance is 5 ohms or less, replace fuse No. 21 and retest system. If resistance is more than 5 ohms, repair circuit No. 489 (Pink/Black wire) for open and retest system.
9. To check circuit No. 397 (Black/White wire) for open, measure resistance between GEM connector C233, pins No. 25 (Black/White wire), No. 26 (Black/White wire) and GEM connector C234, pin No. 15 (Black/White wire). If resistance is less than 5 ohms, go to self test diagnostics for Generic Electronic Module (GEM). See MODULE COMMUNICATIONS NETWORK article and retest system. If resistance is more than 5 ohms, repair circuit No. 397 (Black/White wire) for open and retest system.

Fig 1: Identifying GEM Connectors GEM Connector C233 (Windstar)

Courtesy of FORD MOTOR CO.

Fig 2: Identifying GEM Connectors GEM Connector C234 (Windstar)

Courtesy of FORD MOTOR CO.