GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Theft Deterrent System Schematics

DEFINITION: The horn does not sound when the content theft deterrent (CTD) system is in alarm mode.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Perform one of the following to activate the content theft deterrent (CTD) Alarm Mode:

    • Operate the PANIC button on the keyless entry transmitter.
    • Complete the following steps:
        1. Open the driver 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 door.
        5. Open the driver door.

Do all of the alarm mode functions activate, the lights flash and the 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 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 Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

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