GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Theft Deterrent System Schematics

Connector End View Reference: Theft Deterrent System Connector End Views

DEFINITION: The horn does not sound when the CTD system is in alarm mode.

1

Did you perform A Diagnostic System Check - Theft Deterrent?

Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2

Perform one of the following to activate the CTD Alarm Mode:

    • Operate the PANIC button on the keyless entry transmitter.
    • Complete the following steps:
        1. Open the driver's window.
        2. Lock the vehicle using the power door lock switches.
        3. Wait for the SECURITY telltale to turn off.
        4. Reach in and unlock the driver's door.
        5. Open the driver's door.

Do all of the alarm mode functions activate (lights flash and horn pulses)?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Are only the horns inoperative?

Go to Step 4

Go to Content Theft Deterrent (CTD) Alarm Mode Inoperative

4

Operate the horns from the horn pad.

Do the horns operate properly?

Go to Step 5

Go to Horns Inoperative in Horns

5

Test the control circuit of the horn relay for an open between the body control module (BCM) and the horn relay. Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 6

6

Inspect for poor connections at the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 7

7

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 8

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8

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3