GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the Defogger System Check?

--

Go to Step 2

Go to Defogger System Check

2

  1. Disconnect the rear window defogger relay.
  2. Turn the ignition switch to the RUN position.
  3. Use a test lamp to probe between B+ and the rear window defogger relay connector terminal A1 (CKT 292).

Does the test lamp light?

--

Go to Step 5

Go to Step 3

3

Use a test lamp to probe between the rear window defogger relay connector terminal C 1 (CKT 293) and ground.

Does the test lamp light?

--

Go to Step 8

Go to Step 4

4

  1. Replace the rear window defogger relay.
  2. Test the system again.

Is the repair complete?

--

Go to Defogger System Check

--

5

Inspect for a short to ground in CKT 292 (LT BLU).

Did you find a short to ground on the circuit?

--

Go to Step 6

Go to Step 7

6

  1. Locate and repair the short to ground in CKT 292 (LT BLU).
  2. Retest the circuit.

Is the repair complete?

--

Go to Defogger System Check

--

7

Replace the heater-a/c control. Refer to Control Assembly Replacement in HVAC Systems.

Is the repair complete?

-

Go to Defogger System Check

--

8

  1. Locate and repair a short to B+ in CKT 293 (PPL).
  2. Inspect the system again.

Is the repair complete?

--

Go to Defogger System Check

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