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

Outside Rearview Mirror Switch B+

1

1

--

--

Left/Right Mirror Horizontal Motor Control

2

2

--

--

Left/Right Mirror Vertical Motor Control

2

2

--

--

Left/Right Mirror Motor Common Control

2

2

--

--

Outside Rearview Mirror Switch Ground

--

1

--

--

1. Outside Rearview Mirror Functions Inoperative-BOTH

2. Outside Rearview Mirror Functions Inoperative-ONE

Circuit/System Description

The outside rearview mirror switch supplies both voltage and ground to the outside rearview mirror motors. When the outside rearview mirror switch is being pressed the switch supplies the voltage and ground to the proper circuits to engage the proper mirror motor.

Reference Information

Schematic Reference

Outside Rearview Mirror Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Outside Mirror Description and Operation

Electrical Information Reference

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the operation of each outside rearview mirror while using the outside rearview mirror switch. The appropriate mirror should move in the direction commanded.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the power mirror switch.
  2. Test for less than 10 ohms between the ground circuit terminal D and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Verify that a test lamp illuminates between the B+ circuit terminal E and ground.
  5. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  6. Connect the harness connector at power mirror switch.
  7. Disconnect the harness connector at the appropriate outside rearview mirror.
  8. Connect a test lamp between the control circuit terminal D and the control circuit terminal C.
  9. Operate the vertical switch UP and DOWN. The test lamp should turn ON when commanding the UP and DOWN states.
  10. If the test lamp remains OFF during either of the commands, test for a short to voltage, short to ground or an open/high resistance on the control circuits. If the circuits test normal, replace the power mirror switch.
  11. Connect a test lamp between the control circuit terminal F and the control circuit terminal C.
  12. Operate the horizontal switch LEFT and RIGHT. The test lamp should turn ON when commanding the LEFT and RIGHT states.
  13. If the test lamp remains OFF during either of the commands, test for a short to voltage, short to ground or an open/high resistance on the control circuits. If the circuits test normal, replace the power mirror switch.
  14. If all circuits test normal, test or replace the outside rearview mirror.

Component Testing

Outside Rearview Mirror Switch

  1. Ignition OFF, disconnect the harness connector at the outside rearview mirror switch.
  2. Test for infinite resistance between all of the signal terminals and the voltage supply terminal and the ground circuit with the switch in the open position.
  3. If less than the specified range, replace the rearview mirror switch.
  4. Test for less than 1 ohm between all of the control terminals and ground with the outside rearview mirror switch in the proper positions.
  5. If greater than the specified range, test the ground circuit for an open/high resistance. If the circuits test normal, replace the rearview mirror switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Power Mirror Replacement
    •  Power Mirror Switch Replacement