GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION: Testing the rear defogger grid lines for proper operation.

1

  1. Turn the ignition to switch to RUN.
  2. Press the rear defog button.

After five minutes, does the rear defogger feel warm?

--

Go to Step 2

Go to Step 3

2

  1. Press the rear defog button if timed out.
  2. Connect test lamp to ground.
  3. Touch the other end of the test lamp to the middle of each rear defogger grid line.

Does the test lamp glow dimly?

--

Go to Step 4

Go to Step 3

3

Inspect the rear defogger connector for proper connection. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Are the electrical contacts OK?

--

Go to Rear Window Defogger Inoperative

Go to Step 5

4

  1. Move the test lamp along the grid line.
  2. Move the test lamp from left to right of the rear window.
  3. An open is located when the test lamp goes out.

Was an open in the rear defogger grid line located?

--

Go to Grid Line Repair

Go to Step 6

5

Repair the rear defogger electrical connector.

Is the repair complete?

--

Go to Step 6

--

6

Operate the system in order to verify the repair.

Did you find and correct the condition?

--

System OK

Go to Step 2