GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2007 🢒 XLR 🢒 Safety and Security 🢒 Theft Deterrent 🢒 Theft Deterrent Alarm Inoperative

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 theft deterrent alarm siren is part of the Content Theft Deterrent (CTD) System. The CTD system is an internal function of the body control module (BCM) which utilizes class 2 serial data and various switch input information to perform CTD functions. When the BCM detects an unauthorized entry, it will activate the horns, exterior lamps, and the theft deterrent siren (UA2 RPO).

Reference Information

Schematic Reference

Theft Deterrent System Schematics

Connector End View Reference

Theft Deterrent System Connector End Views

Description and Operation

Content Theft Deterrent (CTD) Description and Operation

Electrical Information Reference

    •  Testing for Intermittent Conditions and Poor Connections
    •  Circuit Testing
    •  Wiring Repairs
    •  Connector Repairs

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

With a scan tool, command the alarm siren ON. Alarm siren should sound.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the theft deterrent alarm siren.
  2. Ignition OFF, test for less then 1 ohm of resistance between the theft deterrent alarm siren ground circuit terminal 4 and ground.
    3. ⇒If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp does not illuminate between the ignition 1 voltage circuit terminal 1 and ground.
    4. ⇒If the test lamp illuminates, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 2 and ground.
    5. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the circuit fuse is open, test circuit for a short to ground. If the circuit tests normal, replace the BCM.
  5. Connect a test lamp between the control circuit terminal 3 and the B+ circuit terminal 2.
  6. Command the alarm siren ON with a scan tool. The test lamp should switch from OFF to ON when commanding the alarm siren ON.
    7. ⇒If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
    ⇒If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  7. If all circuits test normal, test or replace the theft deterrent alarm siren.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, setup, and programming