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 Descriptors

DTC B3821: Left Rear Window Relay Power Circuit

DTC B3824: Right Rear Window Relay Power Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Driver Door Module B+

1, 3

1

--

--

LR Window Switch B+

1, 3

3

--

--

Front Passenger Door Module B+

2, 4

2

--

--

RR Window Switch B+

2, 4

4

--

--

Power Window Switch Right Rear Down Signal

B3823

B3823

B3823

--

Power Window Switch Right Rear Up Signal

B3822

B3822

B3822

--

Power Window Switch Left Rear Down Signal

B3820

B3820

B3820

--

Power Window Switch Left Rear Up Signal

B3819

B3819

B3819

--

Power Window Lockout Left Rear Control

B3821

B3821

B3821

--

Power Window Lockout Right Rear Control

B3824

B3824

B3824

--

LR Window Motor Control

3

3

3

--

Passenger Window Motor Control

2

2

2

--

RR Window Motor Control

4

4

4

--

Driver Window Motor Control

1

1

1

--

LR Window Switch Ground

--

3

3

--

RR Window Switch Ground

--

4

4

--

1. Driver Window Malfunction

2. Passenger Window Malfunction

3. Left Rear Window Malfunction

4. Right Rear Window Malfunction

Circuit/System Description

The body control module (BCM) supplies voltage to the rear window switches allowing for normal window operation from the rear switches and the driver master control. If the rear window lockout function is enabled, the BCM will not supply voltage to the rear window switches and the rear windows will only operate when the BCM receives a command to operate the appropriate rear window UP or DOWN from the driver door switch (DDS).

Conditions for Running the DTC

Battery voltage is between 9-16 volts.

Conditions for Setting the DTC

B3821

The BCM detects a fault in the left rear window lockout circuit.

B3824

The BCM detects a fault in the right rear window lockout circuit.

Action Taken When the DTC Sets

The left or right rear power window will be inoperative.

Conditions for Clearing the DTC

    • The DTC will be current for as long as the fault is present.
    • When the fault is no longer present, the DTC will be a history DTC.
    • A history DTC will clear after 50 ignition cycles.

Reference Information

Schematic Reference

Moveable Window Schematics

Connector End View Reference

Component 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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, command the rear windows UP and DOWN by using the window switches on the driver master control and their respective rear window switches. The rear windows should perform the UP and DOWN function from each switch.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the appropriate rear window switch.
  2. Ignition ON, with the rear window switches enabled, test for greater than 10 volts between the control circuit terminal D and ground.
  3. If less than the specified range, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the BCM.
  4. If all circuits test normal, replace the rear window switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Rear Side Door Window Switch Replacement
    •  Control Module References for BCM replacement, setup, and programming