GM Service Manual Online
For 1990-2009 cars only

Diagnostic Aids

    • If the power mirror system fuse is open and a short to ground in the battery positive voltage circuit is not detected, the fault could be a short to ground in one of the power mirror control circuits. This would open the power mirror system fuse when the mirror switch is pressed.
    • If both power mirrors are inoperative on one or more axis, the most probable cause is a power mirror switch failure. However, the fault could be an open circuit on two or more of the power mirror control circuits.
    • The power mirror assembly is equipped with a pigtail harness and is not serviceable. If an internal open or short is detected in the power mirror assembly, replace the power mirror assembly.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests the integrity of both the mirror control circuits and the power mirror switch. If both power mirrors are inoperative on one or more axis, begin testing by disconnecting one of the power mirrors, if an open circuit is detected and repaired for that power mirror, repeat step 6 for the other power mirror.

  2. This step tests the integrity of the battery positive voltage circuit, not the fuse.

Step

Action

Yes

No

Schematic Reference: Outside Rearview Mirror Schematics

1

Did you review the Outside Mirror Description and Operation?

Go to Step 2

Go to Symptoms - Doors

2

  1. Place the mirror selector switch in the LEFT mirror position.
  2. Activate the mirror position switch in the UP, DOWN, LEFT and RIGHT directions and note the operation.
  3. Place the mirror selector switch in the RIGHT mirror position.
  4. Activate the mirror position switch in the UP, DOWN, LEFT and RIGHT directions and note the operation.

Do both power mirrors operate properly?

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

Go to Step 3

3

Are both the left and right power mirrors completely inoperative?

Go to Step 4

Go to Step 6

4

  1. Disconnect the power mirror switch.
  2. Probe the battery positive voltage circuit of the power mirror switch harness connector with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 7

5

Connect a test lamp between the battery positive voltage circuit of the power mirror switch harness connector and the ground circuit of the power mirror switch harness connector.

Does the test lamp illuminate?

Go to Step 9

Go to Step 15

6

  1. Disconnect the appropriate power mirror.
  2. Connect a test lamp between the appropriate mirror motor control circuits of the power mirror harness connector.
  3. Place the mirror selector switch to the mirror to be tested.
  4. Activate the power mirror switch in both directions for the functions being tested.

Does the test lamp illuminate in both directions?

Go to Step 12

Go to Step 8

7

Test the battery positive voltage circuit of the power mirror switch for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 9

8

Test the mirror motor control circuits for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 9

9

  1. If the power mirror(s) were previously disconnected, connect the power mirror(s).
  2. If the power mirror switch was not previously disconnected, disconnect the power mirror switch.
  3. Probe each of the power mirror motor control circuits of the power mirror switch harness connector with a test lamp that is connected to battery positive voltage.

Did the test lamp illuminate at any of the power mirror motor control circuits?

Go to Step 13

Go to Step 10

10

Probe each of the power mirror motor control circuits of the power mirror switch harness connector with a test lamp that is connected to a good ground.

Did the test lamp illuminate at any of the power mirror motor control circuits?

Go to Step 14

Go to Step 11

11

Inspect for poor connections at the harness connector of the power mirror switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 16

12

Inspect for poor connections at the harness connector of the power mirror(s). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 17

13

Repair the short to ground in the power mirror motor control circuit(s). Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 18

--

14

Repair the short to voltage in the power mirror motor control circuit(s). Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 18

--

15

Repair the open in the power mirror switch ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 18

--

16

Replace the power mirror switch. Refer to Power Mirror Switch Replacement .

Did you complete the replacement?

Go to Step 18

--

17

Replace the power mirror motor(s). Refer to Outside Rearview Mirror Replacement .

Did you complete the replacement?

Go to Step 18

--

18

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2