B320B

DTC B320A or B320B

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 provide an overview of each diagnostic category.

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

Diagnostic Fault Information






Circuit/System Description

The front and rear power windows are controlled by the driver door module (DDM) and front passenger door module (PDM). The DDM and PDM each contain power window switches that are integrated into the module. The DDM contains the master power window switch that controls all power window operations. The DDM supplies the left rear power window switch with a 12-volt reference and signal circuit. The power window switch contained in the PDM controls the front passenger window operation only. The PDM supplies the right rear power window switch with a 12-volt reference and signal circuit.

When the driver power window switch is activated to a desired position, the DDM examines the request and checks for messages from other vehicle control modules prohibiting window movement. If no prohibitive messages have been received, the DDM will send a LIN serial data message to the driver door window motor to move the window to the desired position.

When the DDM receives a request to operate one of the right side passenger windows from the master switch, a GMLAN serial data message is sent to the PDM. The PDM examines the request and checks for messages from other vehicle control modules prohibiting the window movement. If no prohibitive messages have been received, the PDM will send a LIN serial data message to the appropriate window motor to move the window as requested.

The DDM and PDM supply there respective rear power window switches with a 12-volt reference and signal circuit. The rear power window switches contain separate resistors for each switch position. When a rear power window switch is activated, the associated door control module interprets the signal and checks for messages from other vehicle control modules prohibiting the window movement. If no prohibitive messages have been received, the door control module sends a LIN serial data message to the appropriate power window motor commanding the requested window position. For more detailed information concerning power window operation refer to Power Windows Description and Operation.

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

Front Door, Rear Door, or Middle Door window motor not normalized/programmed or an internal malfunction has been detected by the DDM or PDM.

Action Taken When the DTC Sets

Power window express functions are 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 malfunction-free ignition cycles have occurred.

Circuit/System Testing

1. Ignition ON, install a scan tool and clear the DTC.
2. Reprogram the affected power window motor.
3. Operate the vehicle within the conditions for running the DTC and verify the DTC does not reset.

• If the DTC resets, replace the inoperative power window motor.

Repair Instructions

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

* Window Motor Programming - Express Function
* Front Side Door Window Regulator Replacement
* Rear Side Door Window Regulator Replacement