Test H: Mirrors Do Not Defog Properly
- Ensure gearshift selector in Park. Turn ignition switch to RUN position. Turn rear window defogger on. If rear window defogs or heats up, go to next step. If rear window does not defog or heat up, repair rear window defogger system as necessary. See REAR WINDOW DEFOGGERS - EXPEDITION & NAVIGATOR article.
- Check both outside rearview mirror defog operation. If defog function is operating properly, go to next step. If defog function is not operating properly, go to step 4 .
- Turn ignition switch to LOCK position. Measure resistance between ground and inoperative mirror harness connector terminal No. 3 (Black wire). See Figure . If resistance is less than 5 ohms, replace mirror glass. Recheck system operation. If resistance is 5 ohms or greater, repair open or high resistance in Black wire. See WIRING DIAGRAMS .
- Check defogger switch indicator light with defogger on. If switch indicates system is on, repair open in Dark Green/Violet wire between rear window defogger switch, CJB and outside rear view mirror(s). See WIRING DIAGRAMS . Recheck system operation. If switch does not indicate system is on, go to next step.
- Check fuse No. 17 (10-amp) in Central Junction Box (CJB). If fuse is okay, repair open in CJB as necessary. If fuse is open, repair short to ground in Dark Green/Violet wire between rear window defogger switch and outside rear view mirror(s). Replace fuse and recheck system operation.