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 B3820 00: Left Rear Window Down Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

DDS B+

1

1

--

--

LR Window Switch B+

3

3

--

--

PDS B+

2

2

--

--

RR Window Switch B+

4

4

--

--

LR Window Switch Down Signal

B3820 00

B3820 00

B3820 00

--

LR Window Switch Up Signal

B3819 00

B3819 00

B3819 00

--

RR Window Switch Down Signal

B3823 00

B3823 00

B3823 00

--

RR Window Switch Up Signal

B3822 00

B3822 00

B3822 00

--

Passenger Window Motor Control

B3205 00

B3205 0B

B3205 00

--

Driver Window Motor Control

B3205 00

B3205 0B

B3205 00

--

LR Window Motor Control

3

3

3

--

RR Window Motor Control

4

4

4

--

LR Window Switch Lockout Control

B3821 00

B3821 00

B3821 00

--

RR Window Switch Lockout Control

B3824 00

B3824 00

B3824 00

--

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) monitors the window UP/DOWN command from the driver door switch (DDS). When the rear window UP or DOWN command is received, the BCM sends a signal to the appropriate rear window switch. The rear window switches continuously monitor the up and down signal circuits, if no function is being commanded, the signal voltage is at approximately B+ voltage. If the UP or DOWN function is commanded, the BCM signal voltage drops approximately 0.5 volts and the appropriate rear window switch will then command the window in the UP or DOWN direction.

Conditions for Running the DTC

    • Battery voltage is between 9-16 volts.
    • The ignition switch is in the ON position.
    • The BCM has attempted to energize the left rear power window down relay control circuit.

Conditions for Setting the DTC

The BCM detects a fault in the left rear window down circuit

Action Taken When the DTC Sets

The left rear power window will be inoperative from the driver master control.

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

Window Systems Connector End Views

Power Windows 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

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

Circuit/System Verification

Command the left rear door window UP and DOWN with a scan tool. The left rear door window should perform the UP and DOWN function.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the left rear window switch.
  2. Ignition ON, test for greater than 9 volts between the signal circuit terminal C and ground while commanding the left rear window DOWN by using the LR window switch on the driver master control.
  3. If less than the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the BCM.
  4. If the circuit tests normal, replace the left 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, programming, and setup