GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Start the engine.
  2. Depress the rear window defogger switch.
  3. Observe the rear window defogger indicator on the switch.

Does the rear window defogger indicator illuminate?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3

Connect a test lamp between the rear window defogger grid and a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 6

4

Connect a test lamp between the left side of the rear window defogger grid and the right side of the rear window defogger grid.

Does the test lamp illuminate?

Go to Defogger Grid Lines Diagnosis

Go to Step 5

5

Repair an open or high resistance on the ground circuit of the rear window defogger. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 7

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6

Repair an open or high resistance on the supply circuit of the rear window defogger. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 7

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7

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2