B3820

DTC B3820

DTC DESCRIPTOR

DTC B3820 00
Left Rear Window Down Control Circuit

DIAGNOSTIC FAULT INFORMATION
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

CIRCUIT/SYSTEM DESCRIPTION
The body control module (BCM) energizes the control side of the left rear power window down relay upon receiving a GMLAN message from the driver door switch (DDS).

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 left rear window down circuit is shorted to ground.

ACTION TAKEN WHEN THE DTC SETS
The BCM will not attempt left rear window down operation.

CONDITIONS FOR CLEARING THE DTC
- When the output request is not active the DTC will be a history status code.
- The history code will clear after 50 fault free ignition cycles or by using the scan tool clear DTCs feature.

CIRCUIT/SYSTEM TESTING
1. Disconnect the left rear window switch connector and connect a test lamp from the down signal circuit to ground.
2. Ignition ON, verify that the test lamp illuminates when the left rear down switch on the DDS is activated.
- If the test lamp does not illuminate test the left rear window down signal circuit for a short to ground. If the circuit tests normal replace the BCM.
3. If the circuits test 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. Verification Tests Programming and Relearning