Chart 6A/6B Improper Rear Defogger Operation

Diagnostic Chart:

Electrical Diagram:

CIRCUIT DESCRIPTION

The programmer provides a ground for the defogger relay when it receives a command from the Body Control Module (BCM) via the data line. The CCP sends a signal to the BCM when a rear defogger command is received. Then, the BCM checks the status of the hard and soft tops to be sure one or the other is up. If neither top is up, the BCM will not enable the rear defogger. If the soft or hard top is up, the BCM times the operation initially for 10 minutes, then commands the programmer to deactivate the relay ground. Additional requests for rear defogger are for S minute intervals thereafter, until a new ignition cycle occurs.

TEST DESCRIPTION

Test numbers refer to circled numbers on the diagnostic chart.

1. This step checks to see if a short to voltage is giving a constant power feed to the defogger.

2. This step checks to see if relay is at fault.

3. This step checks to see if programmer is commanding defogger 'ON'.

4. This step checks power to the relay.

5. This step checks the resistance across the relay to determine if relay is faulty.

6. This step determines if power is being received by the defogger grid.

7. Checks for programmer command for defog operation.

8. Checks to see if Climate Control Driver Information Center (CCDIC) is requesting rear defog.