GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you review the rear window defogger circuit description and perform the necessary inspections?

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Go to Step 2

Go to Symptoms

2

Verify that the defogger indicator is always on.

Does the defogger indicator operate normally?

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Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the HVAC control connector C4.
  3. Turn the ignition switch to the RUN position.

Is the rear defogger on?

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Go to Step 4

Go to Step 5

4

Repair the short to B+ in circuit 193.

Did you complete the repair?

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Go to Step 6

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5

Replace the HVAC control. Refer to the appropriate procedure:

    •  Control Assembly Replacement in HVAC Systems - Manual
    •  Control Assembly Replacement in HVAC Systems - Automatic

Did you complete the repair?

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Go to Step 6

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6

Operate the system in order to verify the repair.

Did you find and correct the condition?

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System OK

Go to Step 3