GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

Yes

No

1

Inspect the rear window defogger.

Does the rear window defogger work?

--

Go to Step 4

Go to Step 2

2

Repair the rear window defogger before proceeding with the outside mirror diagnosis.

Is the repair complete?

--

Go to Step 3

--

3

Test the outside mirror defoggers.

Does the repair of the rear window defogger system also fix the problem with the outside mirror defoggers?

--

System OK

Go to Step 4

4

Inspect fuse EF27.

Is fuse EF27open?

--

Go to Step 5

Go to Step 6

5

  1. Check for a short circuit and repair it, if necessary.
  2. Replace the fuse.

Is the repair complete?

--

System OK

--

6

  1. On the side of the vehicle which has the malfunctioning mirror defogger, remove the black plastic escutcheon from the trim panel side of the door.
  2. Disconnect the outside mirror electrical connector.
  3. Turn the ignition ON.
  4. Turn the defogger ON.
  5. Use a voltmeter to backprobe terminal 3 (GRY) at the mirror electrical connector.

Does the voltmeter meausre within the specified range?

11-14 V

Go to Step 8

Go to Step 7

7

Repair the open circuit between fuse EF27 and the mirror connector.

Is the repair complete?

--

System OK

--

8

  1. Turn the ignition OFF.
  2. Disconnect the outside mirror electrical connector.
  3. Use an ohmmeter to measure the resistance between terminal 2 (BLK) of the mirror connector and ground.

Does the ohmmeter indicate the specified value?

0 ohms

Go to Step 10

Go to Step 9

9

Repair the open ground circuit for the outside rearview mirror.

Is the repair complete?

--

System OK

--

10

Replace the defective outside rearview mirror.

Is the repair complete?

--

System OK

--