Power Mirrors Inoperative

Power Mirrors Inoperative

Diagnostic Instructions

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

Circuit/System Description

The driver door module (DDM) and passenger door module (PDM) each provide motor control output functions for their respective mirrors. These output controls allow each door module to command their respective power mirrors in horizontal and vertical positions. The power mirror switch is integrated into DDM. When the DDM detects an active mirror command from the power mirror switch, the DDM will send a GMLAN serial data message to the PDM. Each door module will command there respective mirror motor in the appropriate direction by applying ground or voltage to the control circuit, depending on the desired mirror position. For more detailed information concerning power mirror operation refer to Outside Mirror Description and Operation.

Circuit/System Testing

1. Ignition ON, verify with a scan tool the mirror direction switch parameter changes as the switch is activated. The scan tool should change between UP, DOWN, LEFT, RIGHT.

• If the function does not perform as specified, replace the DDM.

2. Verify with a scan tool the mirror select switch parameter changes as the switch is activated. The scan tool should change between RIGHT and LEFT.

• If the function does not perform as specified, replace the DDM.

3. Ignition OFF, disconnect the appropriate outside rearview mirror C1 and C2 harness connectors.
4. Ignition OFF, test for less than 1.0 ohm of resistance at each mirror motor control circuit between the outside rearview mirror C1 and C2 harness connectors and ground.

• If greater than the specified range, test the appropriate mirror motor control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the appropriate door control module.

5. Connect a test lamp between mirror motor UP control circuit terminal 1 and mirror motor DOWN control circuit terminal 2.
6. Command the appropriate mirror to the UP and DOWN positions with a scan tool. The test lamp should turn ON when commanding the UP and DOWN states.

• If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuit tests normal, replace the appropriate door control module.

7. Connect a test lamp between mirror motor LEFT control circuit terminal 1 and mirror motor RIGHT control circuit terminal 2.
8. Command the appropriate mirror to the LEFT and RIGHT positions with a scan tool. The test lamp should turn ON when commanding the LEFT and RIGHT states.

• If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuit tests normal, replace the appropriate door control module.

9. If all circuits test normal, test or replace the appropriate outside rearview mirror.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Power Mirror Replacement
* Control Module References for DDM or PDM replacement, setup, and programming. Programming and Relearning