LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Ford >> 1998 >> Windstar Base, 3.0 U >> Repair and Diagnosis >> Body & Frame >> Door Locks >> Remote Keyless Entry System >> System Testing >> Test B: No Communication With Gem Module
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Test B: No Communication With Gem Module

  1. Check For Remote Anti-Theft Personality (RAP) Module  - Check that vehicle is equipped with RAP module. If vehicle is equipped with RAP module, go to next step. If vehicle is not equipped with RAP module, go to step 6).
  2. Check For Communication To RAP Module  - Perform Data Link Diagnostic Test. If response for RAP is RAP=NO RESPONSE/NOT EQUIPPED, go to next step. If response is not as indicated, go to step 6).
  3. Check Fuse No. 19 (15-A)  - Remove fuse No. 19 (15-amp) from fuse junction panel. With an ohmmeter, measure resistance between fuse terminals. If resistance is less than 5 ohms, repair open in Black/Light Green wire circuit. Restore and retest system. If resistance is more than 5 ohms, go to next step.
  4. Check GEM  - Disconnect GEM connector C233. Measure resistance of Black/Light Green wire circuit between output cavity of fuse No. 19 and ground. Observe ohmmeter reading. If reading starts at greater than one megohm and steadily drop to less than 3000 ohms, replace GEM. Restore and retest system. If ohmmeter does not drop as indicated, go to next step.
  5. Check RAP Module  - Disconnect RAP connector. Measure resistance of Black/Light Green wire circuit between output cavity of fuse No. 19 and ground. Observe ohmmeter reading. If reading starts at greater than one megohm and steadily drop to less than 3,000 ohms, replace RAP module. Restore and retest system. If ohmmeter does not drop as indicated, repair short in Black/Light Green wire circuit. Restore and retest system.
  6. Check Black/Light Green Wire Circuit For Power  - Disconnect GEM connector C233. With a voltmeter, measure voltage of Black/Light Green wire circuit between GEM connector terminal No. 13 and ground. See Fig 1 . If battery voltage is present, go to step 10). If battery voltage is not present, go to next step.
    Fig 1: Identifying Generic Electronic Module (GEM) C233 & C234 Connector Terminals
    G97G28551Courtesy of FORD MOTOR CO.
  7. Check Black/Light Green Wire Circuit For Short  - Remove fuse No. 19 (15-amp). Measure resistance of Black/Light Green wire circuit between GEM connector C233 terminal No. 13 and ground. If resistance is less than 10 k/ohms, repair short in Black/Light Green wire circuit. Restore and retest system. If resistance is not less than 10 k/ohms, go to next step.
  8. Check Supply Fuse No. 19  - Remove fuse No. 19 (15-amp). Measure voltage at fuse input cavity. If battery voltage is present, go to next step. If battery voltage is not present, service supply circuit to fuse No. 19 (15-amp). Restore and retest system.
  9. Check Black/Light Green Wire Circuit For Open  - Measure resistance of Black/Light Green wire circuit between GEM connector C233 terminal No. 13 and output cavity of fuse No. 19. If resistance is less than 5 ohms, replace fuse No. 19. Restore and retest system. If resistance is more than 5 ohms, repair open in Black/Light Green wire circuit. Restore and retest system.
  10. Check Pink/Black Wire Circuit For Power  - Disconnect GEM connector C234. Turn ignition to run position (engine off). Measure voltage at GEM connector Pink/Black wire terminal No. 22. If battery voltage is present, go to step 14). If battery voltage is not present, go to next step.
  11. Check Pink/Black Wire Circuit For Short  - Remove fuse No. 21 (10-amp) from fuse junction panel. Measure resistance of Pink/Black wire circuit between GEM connector C234 terminal No. 13 and ground. If resistance is less than 10 k/ohms, repair short in Pink/Black wire circuit and replace fuse No. 21 (10-amp). Restore and retest system. If resistance is not less than 10 k/ohms, go to next step.
  12. Check Power Supply To Fuse No. 21  - Remove fuse No. 21 (10-amp). Measure for voltage at fuse input cavity. If battery voltage is present, go to next step. If battery voltage is not present, replace fuse No. 21. Restore and retest system.
  13. Check Pink/Black Wire Circuit For Open  - Measure resistance of Pink/Black wire circuit between GEM connector C234 terminal No. 13 and fuse No. 21 output cavity. If resistance is less than 5 ohms, replace fuse No. 21. Restore and retest system. If resistance is more than 5 ohms, repair open in Pink/Black wire circuit. Restore and retest system.
  14. Check Black/White Wire Circuit For Open  - Measure resistance of Black/White wire circuit between GEM connector C233 terminals No. 25 and 26 and connector C234 terminal No. 15 and ground. If resistance is less than 5 ohms in any circuit, no fault is present. See G - TESTING W/CODES article in the ENGINE PERFORMANCE section for on-board computer diagnostics. If resistance is more than 5 ohms, repair open in suspect Black/White wire circuit(s). Restore and retest system.
scientia non olet · About LEMON Manuals