For 1990-2009 cars

### 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 the diagnostic category.

### Circuit/System Description

The content theft deterrent (CTD) system is a software based system in which the body control module (BCM) actively monitors certain inputs to determine if unauthorized vehicle access is being attempted. Based on inputs such as the door ajar switches, and the Trunk ajar switch, the BCM determines whether a CTD alarm is warranted. If unauthorized access is being detected, the BCM will pulse the vehicle horn and flash the turn signals as a means of theft deterrent.

### Diagnostic Aids

The scan tool Last Alarm Caused, 2nd to Last Alarm Caused, and 3rd to Last Alarm Caused parameters may be used to assist in the diagnosis of an intermittent condition.

### Reference Information

#### Schematic Reference

Immobilizer Schematics

#### Connector End View Reference

Immobilizer Connector End Views

#### 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

• | Scan Tool Output Controls

### Circuit/System Testing

1. Ignition ON, while opening and closing each vehicle door, verify that the applicable scan tool door ajar switch parameter cycles between Door Closed and Door Ajar.

⇒ | If the scan tool parameter does not cycle between the specified values, refer to Door Ajar Indicator Malfunction .

2. With the rear compartment lid open, verify the TRUNK AJAR message is displayed on the DIC.

⇒ | If the message is not displayed, refer to Trunk Ajar Indicator Inoperative .

3. With the rear compartment lid closed, verify the TRUNK AJAR message is not displayed on the DIC.

⇒ | If the message is displayed, refer to Trunk Ajar Indicator Always On .

4. Completely lower the driver door window.
5. Ignition OFF, arm the CTD system using the keyless entry system by pressing the transmitter LOCK button twice. Verify the scan tool CTD Status parameter displays Armed.

⇒ | If the parameter does not equal the specified value, refer to Keyless Entry System Inoperative .

6. Without disarming the system, reach in through the open driver window, unlock and open the driver door. Verify the scan tool Content Theft Mode parameter displays Warn Away or Alarm.

⇒ | If the parameter does not equal the specified value, replace the BCM.

7. With the door open, verify the vehicle horn is pulsing and the turn signal lamps are flashing.

⇒ | If the horn is not pulsing, refer to Horns Inoperative .

⇒ | If the turn signal lamps are not flashing, refer to Turn Signal Lamps and/or Indicators Malfunction .

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, setup and programming