2000 Lincoln Navigator 4WDFACTORY OEM SERVICE PROCEDURE

Test F: No Communication With Gem Module

  1. Turn ignition off. Connect NGS tester following manufacturer's instructions. Select GEM PID IGN_S, IGN_R, IGN_O/L and IGN_A. Turn ignition switch through all positions. If PID values agree with switch positions, go to next step. If PID values do not agree with switch positions, repair appropriate ignition switch circuit. Clear DTCs. Recheck system operation.
  2. Turn ignition off. Disconnect central junction box 34-pin connector C243. Measure voltage between ground and central junction box connector terminal No. 11 (Tan/Black wire). See Fig 1 . If more than 10 volts exists, go to next step. If 10 volts or less exists, repair open in Tan/Black wire. Recheck system operation.
  3. Disconnect GEM 18-pin connector C267. Measure voltage between ground and central junction box terminal No. 4 and 16. See Fig 1 . If more than 10 volts exists at both terminals, go to next step. If 10 volts or less exists at either terminal, replace central junction box. Recheck system operation.
    Fig 1: Identifying Central Junction Box & GEM Connector Terminals
    G97A28191Courtesy of FORD MOTOR CO.
  4. Turn ignition off. Disconnect GEM 26-pin connector C239. Measure resistance between ground and GEM connector C239 terminal No. 26 (Black/Light Blue wire). See Figure . If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Black/Light Blue wire. Recheck system operation.
  5. Measure resistance between ground and GEM connector C239 terminal No. 14 (Black/Light Blue wire). If resistance is less than 5 ohms, see MODULE COMMUNICATIONS NETWORK - EXPEDITION & NAVIGATOR article. If resistance is more than 5 ohms, repair open in Black/Light Blue wire. Recheck system operation.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.