GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Strategy Based Diagnosis
    •  Diagnostic Procedure Instructions

DTC Descriptors

DTC B320A 39: Front Door Window Motor Internal Electronic Failure / Discard

DTC B320A 4B: Front Door Window Motor Calibration Not Learned

DTC B320A 42: Front Door Window Motor Calibration Data Set Not Programmed

DTC B320B 39: Rear Door Window Motor Internal Electronic Failure / Discard

DTC B320B 4B: Door Window Motor Calibration Not Learned

DTC B320B 42: Rear Door Window Motor Calibration Data Set Not Programmed

DTC B320C 39: Middle Door Window Motor Internal Electronic Failure / Discard

DTC B320C 4B: Middle Door Window Motor Calibration Not Learned

DTC B320C 42: Middle Door Window Motor Calibration Data Set Not Programmed

Circuit/System Description

The front door, rear door and middle door power window motors communicate with the drivers door module (DDM) , passenger door module (PDM) and rear door modules and middle door modules over the LIN BUS. The motors contain a logic module which must be normalized or programmed any time the window motor is serviced to provide proper operation and communication between door modules and window motors.

Conditions for Running the DTC

Power window switch activated.

Conditions for Setting the DTC

B320A 39, B320B 39, B320C 39

An internal malfunction or a momentary voltage spike has been detected by the DDM or PDM in the power window motor while commanding the window UP/DOWN.

B320A 42, B320B 42, B320C 42

A not normalized/programmed power window motor.

B320A 4B, B320B 4B, B320C 4B

The window motor experiences a loss of voltage in the B+ circuit or an open/high resistance in the serial data circuit.

Action Taken When the DTC Sets

The appropriate power window will malfunction

Conditions for Clearing the DTC

B320A 39, B320B 39, B320C 39

If the DTC is current, the appropriate window motor must be replaced before the DTC can be cleared.

B320A 42, B320B 42, B320C 42

The affected power window motor must be programmed before the DTC can be cleared.

B320A 4B, B320B 4B, B320C 4B

The affected power window motor must be calibrated before the DTC can be cleared.

Reference Information

Schematic Reference

Power Window Schematics

Connector End View Reference

Power Door Systems Connector End Views

Description and Operation

Power Windows Description and Operation

Electrical Information Reference

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

Circuit/System Verification

Ignition ON, observe the operation of each power window while commanding each window UP and DOWN by using the power window switches on the driver master control. Each power window should go UP and DOWN command.

Circuit/System Testing

B320A 39, B320B 39, B320C 39

Ignition ON, command the appropriate power window DOWN and UP with a scan tool. The power window should go DOWN and UP as commanded.

If the DTC is current and the power window is inoperative, replace the power window motor.
If the DTC is history and the power window performs the UP and DOWN functions, clear the DTC.

B320A 42, B320B 42 or B320C 42

Reprogram the appropriate power window and operate the power window within the conditions for running the DTC, verify the DTC does not reset.

If the DTC resets, replace the power window motor.

B320A 4B, B320B 4B or B320C 4B

Command the appropriate power window motor fully DOWN by pressing and holding the window switch for 5 seconds, then command the power window motor fully UP by lifting and holding the window switch for 5 seconds. Operate the power window within the conditions for running the DTC, verify the DTC does not reset

If the DTC resets, replace the power window motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Side Door Window Regulator Replacement
    •  Front Side Door Window Regulator Motor Replacement
    •  Rear Side Door Window Regulator Motor Replacement