GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Heated Mirror Voltage Supply Circuit

1

1

--

--

Heated Mirror Ground Circuit

--

1

1

--

Heated Mirror Grid

1

1

1

--

1 Heated Mirror Inoperative

Circuit/System Description

The heated outside rearview mirrors operate when the rear window defogger is turned ON and will turn OFF when the rear window defogger is turned OFF.

Diagnostic Aids

The rear window defogger controls the heated outside rearview mirror.

Reference Information

Schematic Reference

Outside Rearview Mirror Schematics

Connector End View Reference

Vehicle Access Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Circuit/System Verification

Ignition ON, engage the rear window defogger. Touch the outside rearview mirror face. The heated mirror face should warm up after about a minute.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the outside rearview mirror.
  2. Test for less than 1 ohm of resistance between the ground circuit and ground.
  3. If greater than 1 ohm, test the ground circuit for an open/high resistance.
  4. Connect a test lamp between the control circuit and the ground circuit.
  5. Ignition ON, turn ON the rear window defogger. The test lamp should turn ON and OFF when changing between the commanded states.
  6. If the test lamp remains ON all the time, test for a short to voltage on the control circuit.
    If the test lamp remains OFF all the time, test for a short to ground or an open/high resistance on the control circuit.
  7. If all circuits test normal, test or replace the appropriate outside heated rearview mirror face.

Component Testing

  1. Ignition OFF, disconnect the harness connector at the heated outside mirror.
  2. Test for less than 10 ohms of resistance between the control terminal and the ground terminal of the heated outside mirror.
  3. If the resistance is not within the specified range, replace the appropriate heated outside mirror face.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Outside Rearview Mirror Glass Replacement