GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2006 🢒 Lucerne 🢒 Vehicle Control Systems 🢒 Computer/Integrating Systems 🢒 DTC B1544, B1600, or B1605

DTC Descriptor

DTC B1544 01: Mirror Motors Common Circuit Short to Voltage

DTC B1544 02: Mirror Motors Common Circuit Short to Ground

DTC B1544 04: Mirror Motors Common Circuit Open Circuit

DTC B1600 01: Mirror Motor 1 (vertical) Circuit Short to Voltage

DTC B1600 02: Mirror Motor 1 (vertical) Circuit Short to Ground

DTC B1600 04: Mirror Motor 1 (vertical) Circuit Open Circuit

DTC B1605 01: Mirror Motor 2 (horizontal) Circuit Short to Voltage

DTC B1605 02: Mirror Motor 2 (horizontal) Circuit Short to Ground

DTC B1605 04: Mirror Motor 2 (horizontal) Circuit Open Circuit

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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. When the door modules detect an active mirror command from the outside rearview mirror switch, they will command the respective mirror motor in the appropriate direction. Each door module commands their respective mirror motors by applying a 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 .

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC
    • DTC B1544 01 will set when the DDM or PDM detects a short to voltage in the mirror motor common circuit.
    • DTC B1544 02 will set when the DDM or PDM detects a short to ground in the mirror motor common circuit.
    • DTC B1544 04 will set when the DDM or PDM detects an open in the mirror motor common circuit.
    • DTC B1600 01 will set when the DDM or PDM detects a short to voltage in the mirror motor control circuit.
    • DTC B1600 02 will set when the DDM or PDM detects a short to ground in the mirror motor control circuit.
    • DTC B1600 04 will set when the DDM or PDM detects an open in the mirror motor control circuit.
    • DTC B1605 01 will set when the DDM or PDM detects a short to voltage in the mirror motor control circuit.
    • DTC B1605 02 will set when the DDM or PDM detects a short to ground in the mirror motor control circuit.
    • DTC B1605 04 will set when the DDM or PDM detects an open in the mirror motor control circuit.

Actions Taken When the DTC Sets
    • When DTC B1544 is present, all mirror controls will be disabled.
    • When DTC B1600 is present, the vertical mirror control will be disabled.
    • When DTC B1605 is present, the horizontal mirror control will be disabled.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists.
    • You issue a scan tool CLEAR DTCs command.
    • A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

The following conditions may cause an intermittent malfunction:

    • There is an intermittent short to ground or voltage in a mirror motor control circuit.
    • A mirror motor is shorted internally.

Reference Information

Schematic Reference

Outside Rearview Mirror Schematics

Connector End View Reference

Power Door Systems Connector End Views

Electrical Information Reference

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

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Testing
  1. Ignition OFF, disconnect the appropriate outside rearview mirror C1 harness connector.
  2. Ignition OFF, test for less than 1.0 ohm of resistance at each mirror motor control circuit between the outside rearview mirror C1 harness connector and ground.
    3. ⇒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.
  3. Connect a test lamp between mirror motor UP control circuit terminal 10 and mirror motor DOWN control circuit terminal 9.
  4. 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.
    5. ⇒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.
  5. Connect a test lamp between mirror motor LEFT control circuit terminal 11 and mirror motor RIGHT control circuit terminal 10.
  6. 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.
    7. ⇒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. If all circuits test normal, test or replace the appropriate mirror.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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