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Rear Defogger Relay Open

When Monitored: With the ignition in the run position.

Set Condition: The rear defogger relay output of the BCM does not have battery voltage.

Possible Causes are:

  1. Turn ignition off. Remove and inspect the PDC fuse No. 2. Is the PDC fuse No. 2 open? If yes, go to next step. If no, go to step  4 .
  2. Turn ignition off. Lower the Junction Block and remove the Rear Window Defogger Relay. Measure the resistance of the Fused B (+) circuits in the Rear Window Defogger Relay connector to ground. Is the resistance less than 5 ohms? If yes, repair the fused B (+) circuit for a short to ground. Perform MEMORY SYSTEM VERIFICATION TEST  under VERIFICATION TESTS. If no, go to next step.
  3. Turn ignition off. Disconnect the Rear Window Defogger connector at the rear window Grid. Remove the Rear Window Defogger Relay from the Junction Block. Measure the resistance between ground and the Rear Window Defogger Relay Output circuit at the Rear Window Defogger connector. Is the resistance less than 5 ohms? If yes, repair the rear window defogger relay output circuit for a short to ground. Perform MEMORY SYSTEM VERIFICATION TEST  under VERIFICATION TESTS. If no, replace PDC fuse. No. 2. Perform MEMORY SYSTEM VERIFICATION TEST  under VERIFICATION TESTS.
  4. Turn ignition off. Lower the Junction Block and remove the Rear Window Defogger Relay. Turn ignition on. Measure the voltage of the Fused B (+) circuit in the Rear Window Defogger Relay connector. Is the voltage more than 10 volts? If yes, go to next step. If no, repair the open fused B (+) circuit from PDC fuse No. 2. Perform MEMORY SYSTEM VERIFICATION TEST  under VERIFICATION TESTS.
  5. Turn ignition off. Lower the Junction Block and remove the Rear Window Defogger Relay. Connect a test light between cavities No. 85 & 86 of the Rear Window Defogger Relay connector. Turn ignition on. Using the DRBIII(R), actuate the R Defog Relay and observe the test light. Does the test light flash on and off when the relay is actuated? If yes, replace the rear window defogger relay. Perform MEMORY SYSTEM VERIFICATION TEST  under VERIFICATION TESTS. If no, go to next step.
  6. Turn ignition off. Lower the Junction Block and remove the Rear Window Defogger Relay. Disconnect and remove the Body Control Module. Measure the resistance of the rear window defogger relay control circuit to ground. Is the resistance less than 1000 ohms? If yes, replace the junction block. Perform MEMORY SYSTEM VERIFICATION TEST  under VERIFICATION TESTS. If no, go to next step.
  7. Turn ignition off. Lower the Junction Block and remove the Rear Window Defogger Relay. Disconnect and remove the Body Control Module. Measure the resistance of the Rear Window Defogger Relay Control circuit between the relay connector and the J/B-BCM connector in the Junction Block. Is the resistance less than 5 ohms? If yes, replace the body control module. Perform MEMORY SYSTEM VERIFICATION TEST  under VERIFICATION TESTS. If no, replace the junction block. Perform MEMORY SYSTEM VERIFICATION TEST  under VERIFICATION TESTS.
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