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.

Circuit/System Description

The content theft system is controlled by the body control module (BCM). The BCM monitors the status of the doors, ignition switch and if equipped, the rear liftgate/liftglass/Swing gate. When the proper conditions are met the BCM enables the content theft system. The BCM will sound the horn and flash the lights when an unauthorized entry has been detected.

Reference Information

Schematic Reference

Theft Deterrent System Schematics

Description and Operation

Content Theft Deterrent (CTD) 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 List
    •  Scan Tool Data Definitions

Circuit/System Verification

  1. Verify that the keyless entry, horn and exterior lighting systems are functional.
  2. With the ignition ON, lower the driver door window. Ignition OFF, remove key and close and lock all doors and liftgate/liftglass/Swing gate (if equipped). Reach in and open the driver door with the driver door handle. Alarm should sound and exterior lights should flash.

Circuit/System Testing

  1. Ignition ON, with the scan tool, check for any current DTC. Diagnose any current DTC.
  2. With the scan tool verify all entry points are closed. Perform system verification. Verify that the content theft system is inoperative.
  3. If the theft system is inoperative, replace the BCM. Refer to repair instructions.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, programming and setup