GM Service Manual Online
For 1990-2009 cars only

Test Description

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

  1. Determines if the mirror heating element supply voltage circuit is shorted to battery positive voltage within the module.

  2. Determines if the mirror heating element supply voltage circuit of the mirror harness is shorted to battery positive voltage.

Step

Action

Yes

No

Schematic Reference: Outside Rearview Mirror Schematics

Connector End View Reference: Power Door Systems Connector End Views

1

Did you perform the Door Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Door Systems

2

Verify that the Heated Mirrors Inoperative complaint is present.

Does the heated mirrors system operate as described in the Description and Operation?

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

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the mirror harness connector from the door module associated with the inoperative outside mirror.
  3. Connect a test lamp between the mirror heating element supply voltage circuit and the mirror heating element ground circuit at the door module pins.
  4. Make sure that all other harness connectors to the door module remain connected.
  5. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 9

Go to Step 4

4

With the test lamp still connected between the mirror heating element supply voltage circuit and the mirror heating element ground circuit at the door module pins, command the mirrors to heat by turning ON the rear defroster.

Does the test lamp illuminate?

Go to Step 5

Go to Step 9

5

  1. Turn OFF the ignition.
  2. Connect the mirror harness connector to the door module associated with the inoperative outside mirror.
  3. Carefully remove the mirror face (glass) from the mirror that does not heat. Refer to Outside Rearview Mirror Glass Replacement .
  4. Disconnect the heated mirror circuit connectors from the mirror face.
  5. Connect a test lamp between the heated mirror circuit connectors.
  6. Turn ON the ignition, with the engine OFF.

Does the test light illuminate?

Go to Step 7

Go to Step 6

6

With the test lamp still connected between the heated mirror circuit connectors, command the mirror to heat by turning ON the rear window defroster.

Does the test lamp illuminate?

Go to Step 8

Go to Step 7

7

Inspect for poor connections at the harness connector of the inoperative outside rear view mirror. 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 13

Go to Step 12

8

Inspect for poor connections at the harness connector of the inoperative outside rear view mirror face. 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 13

Go to Step 10

9

Inspect for poor connections at the C4 harness connector of the door module associated with the inoperative outside rear view mirror. 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 13

Go to Step 11

10

Replace the inoperative outside rear view mirror face. Refer to Outside Rearview Mirror Glass Replacement .

Did you complete the replacement?

Go to Step 13

--

11

Replace the door module of the inoperative mirror. Refer to Door Control Module Replacement .

Did you complete the replacement?

Go to Step 13

--

12

Replace the inoperative outside rear view mirror. Refer to Power Mirror Replacement .

Did you complete the replacement?

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2