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Rear Window Defogger Grid Inoperative

Possible Causes:

Testing

  1. Turn ignition on. Turn rear window defogger switch on and off. If indicator light turns on and off, go to next step. If indicator light does not turn on and off, go to step  4 .
  2. Turn ignition off. Open tailgate. Disconnect passenger's side defogger grid connector. Check resistance between rear window defogger grid harness connector (Black wire) and ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or poor connection on Black wire to ground, at driver's kick panel.
  3. Disconnect passenger's side defogger grid connector. Turn ignition on. Turn rear window defogger on. Check voltage between rear window defogger grid harness connector (Gray wire) and ground. If battery voltage exists, repair rear window defogger grid. If battery voltage does not exist, repair open on circuit between defogger relay and defogger grid.
  4. Using scan tool, check R DFOG SWITCH input/output display. Turn rear window defogger on and off. If scan tool displays switch turning on and off, go to next step. If scan tool does not display switch turning on and off, go to step  11 .
  5. Turn ignition off. Remove fuse No. 2 from Power Distribution Center (PDC), located in right side of engine compartment, next to battery. If fuse is faulty, go to next step. If fuse is okay, go to step  8 .
  6. Remove rear window defogger relay. Check resistance between rear window defogger relay cavity terminal C1 and ground. If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, repair short to ground on Black/Pink wire between fuse No. 2 and relay cavity terminal C1.
  7. Disconnect driver's side defogger grid connector. Check resistance between rear window defogger grid harness connector (Gray wire) and ground. If resistance is 5 ohms or more, replace fuse No. 2 in PDC and recheck system. If resistance is less than 5 ohms, repair short to ground on Black/White wire and/or Gray wire between relay and defogger grid.
  8. Remove rear window defogger relay. Turn ignition on. Check voltage between rear window defogger relay cavity terminal C1 and ground. If battery voltage exists, go to next step. If battery voltage does not exist, repair open on Black/Pink wire between fuse No. 2 and relay cavity terminal C1.
  9. Replace rear window defogger relay with known-good relay. Turn ignition on. Check system operation. If system does not operate, go to next step. If system operates, discard faulty relay.
  10. Remove fuse No. 17 (10-amp) from fuse block, located on firewall next to glove box. Using a test light connected to ground, probe fuse No. 17 power supply cavity. Using scan tool, actuate R DEFOG RELAY. If test light does not flash on and off when relay is actuated, repair open between relay in PDC and fuse block fuse No. 17. If test light flashes on and off when relay is actuated, repair open on Dark Blue/Red wire between fuse No. 17 an rear window defogger switch terminal No. 3.
  11. Turn ignition off. Remove rear window defogger switch. Remove instrument cluster. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Check resistance of Dark Blue/White wire between rear window defogger switch harness connector terminal No. 2 and instrument cluster harness connector C2 terminal No. 1. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit on Dark Blue/White wire.
  12. Check resistance between rear window defogger switch harness connector terminal No. 2 (Dark Blue/White wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on Dark Blue/White wire.
  13. Turn ignition on. Check voltage between rear window defogger switch harness connector terminal No. 2 (Dark Blue/White wire) and ground. If no voltage exists, go to next step. If voltage exists, repair short to voltage on Dark Blue/White wire.
  14. Turn ignition off. Install instrument cluster. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Connect a jumper wire between rear window defogger switch harness connector terminal No. 2 (Dark Blue/White wire) and ground. Turn ignition on. Using scan tool, check R DEFOG SW status. If status is CLOSED, replace rear window defogger switch. If status is not CLOSED, replace instrument cluster.
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