2000 Lincoln Navigator 4WDFACTORY OEM SERVICE PROCEDURE

Test D: No Communication With Rap Module

  1. Turn ignition off. Check fuses No. 4 (5-amp) and No. 8 (5-amp) in central junction box located behind left side of instrument panel. If fuses are okay, go to next step. If fuse(s) are blown, replace fuse(s). Recheck system operation. If fuse fails again, check for short to ground in appropriate fuse circuit.
  2. Turn ignition off. Disconnect RAP module 22-pin connector C257. Measure voltage between ground and connector C257 terminal No. 12 (Orange/Light Green wire). See Figure . If more than 10 volts exists, go to next step. If 10 volts or less exists, repair short to ground in Orange/Light Green wire. Recheck system operation.
  3. Disconnect RAP module 26-pin connector C256. Turn ignition switch to RUN position. Measure voltage between ground and RAP module 26-pin connector C256 terminal No. 25 (Black/Pink wire). If more than 10 volts exists, go to next step. If 10 volts or less exists, repair open in Black/Pink wire. Recheck system operation.
  4. Turn ignition off. Measure resistance between ground and RAP module 22-pin connector C257 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.