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.

DTC Descriptor

DTC B1724: Mirror Motor Control Circuit 2 Performance

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

5-Volt Reference

2

2

2

--

Driver/Passenger Horizontal Position Data Signal

2

2

2

--

Driver/Passenger Vertical Position Data Signal

2

2

2

--

Driver/Passenger Mirror Right Control

B1723, B1724

1

B1723, B1724

--

Driver/Passenger Mirror Common

B1723, B1724

1

B1723, B1724

--

Driver/Passenger Mirror Down Control

B1723, B1724

1

B1723, B1724

--

Low Reference

--

2

2

--

1. Power Mirror Malfunction

2. Memory Mirror Malfunction

Circuit/System Description

The driver door module (DDM) or passenger door module (PDM) controls the mirror horizontal and vertical motors through the use of bi-directional motor controls. When the mirror is commanded up, voltage is supplied to the mirror vertical motor through the driver/passenger mirror motor right/down motors common circuit and ground is supplied through the driver/passenger mirror motor down control circuit. When the mirror is commanded down, voltage is supplied to the mirror vertical motor through the driver/passenger mirror motor down control circuit and ground is supplied through the driver/passenger mirror motor right/down motors common circuit.

Horizontal controls operate in the same manner with the driver/passenger mirror motor right/down motors common circuit supplying voltage and the driver/passenger mirror motor right control circuit supply a ground to the mirror horizontal motor when the mirror is commanded right. When the mirror is commanded left, voltage is supplied to the mirror horizontal motor through the driver/passenger mirror motor right control circuit and ground is supplied through the driver/passenger mirror motor right/down motors common circuit.

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

A mirror motor control circuit is shorted to voltage or ground.

Action Taken When the DTC Sets

Mirror movement is suspended as long as the fault is present.

Conditions for Clearing the DTC

    • A current DTC will clear when the fault is no longer present.
    • A history DTC will clear after 40 malfunction-free ignition cycles.

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

Command the left and right outside mirror to move up, down, left and right using the mirror directional switch. The mirror should move in the commanded direction.

Circuit/System Testing

  1. Ignition OFF, disconnect the X3 harness connector at the appropriate door module.
  2. Ignition ON, verify a test lamp does not illuminate between the following control circuit terminals and ground:
  3. • Control circuit terminal B4
    • Control circuit terminal B2
    • Control circuit terminal B6
    If the test lamp illuminates, test the appropriate control circuit for a short to voltage.
  4. Ignition OFF, test for infinite resistance between the following control circuits and ground:
  5. • Control circuit terminal B4
    • Control circuit terminal B2
    • Control circuit terminal B6
    If less the specified value, test the appropriate control circuit for a short to ground.
  6. Test for 40-100 ohms between the control circuit terminal B4 and the control circuit terminal B6.
  7. If not within the specified range, test both control circuits for an open/high resistance. If the circuits test normal, test or replace the rearview mirror motor.
  8. Test for 40-100 ohms between the control circuit terminal B2 and the control circuit terminal B6.
  9. If not within the specified range, test both control circuits for an open/high resistance. If the circuits test normal, test or replace the rearview mirror motor.
  10. If all circuits test normal, replace the door module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Outside Rearview Mirror Motor Replacement
    •  Control Module References for DDM or PDM replacement, setup, and programming