GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION: The content theft deterrent system is unable to sound the horn when setting off the alarm.

1

Was the CTD System Check performed?

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Go to Step 2

Go to Content Theft Deterrent (CTD) System Check

2

Test the horn by pressing the horn switch on the steering wheel.

Does the horn sound?

--

Go to Step 3

Go to Step 8

3

Perform the BCM Input/Output test:

  1. Turn off the IP dimmer switch.
  2. Turn the ignition switch to the OFF position.
  3. Remove the MALL PGM fuse.
  4. Turn the ignition switch to the ACC position. The BCM sounds the chimes 4 times. (The number of chimes is equivalent to the BCM type installed on the vehicle.)
  5. Within 1 second, turn the ignition switch from the ACC position to the OFF position and back to the ACC position.
  6. The BCM sounds any stored DTCs.

  7. Turn the IP dimmer switch to the DOME position. The BCM enters the Input/Output test.
  8. Cycle the IP dimmer switch from the DOME position to the OFF position and back to the DOME position in order to move to the next test.
  9. The BCM runs the Input/Output test in numerical order.

    The BCM flashes the fasten belts indicator and sounds the chime a number equivalent to the Input/Output test number:

    • Test 1 de-energizes circuit 1393 (protected courtesy light output).
    • Test 2 energizes circuit 1393.
    • Test 3 grounds circuit 690 (courtesy lights control).
    • Test 4 turns on the headlights.
    • Test 5 energizes the horn relay for 25 minutes by grounding circuit 28, sounding the horn.
    • Test 6 turns on the theft deterrent indicator lamp.
    • Test 7 turns off the theft deterrent indicator lamp.

Does the horn sound when the BCM performs test 5?

--

Go to Step 5

Go to Step 4

4

Did you perform the BCM Diagnostic System Check?

--

Go to Step 6

Go to Diagnostic System Check - Body Control System in Body Control System

5

  1. Turn the ignition switch to the OFF position.
  2. Reinstall the MALL PGM fuse.
  3. Perform the Content Theft Deterrent System Check. Refer to Content Theft Deterrent (CTD) System Check .

Does the content theft deterrent system operate correctly?

--

Go to Step 11

Go to Step 9

6

  1. Disconnect the BCM connector C2.
  2. Use a 10A fused jumper in order to connect momentarily between the BCM harness connector C2 terminal D10 and ground.

Does the horn sound after you connect the fused jumper?

--

Go to Step 7

Go to Step 10

7

  1. Reconnect the BCM connector C2.
  2. Perform the Content Theft Deterrent System Check . Refer to Content Theft Deterrent (CTD) System Check .

Does the content theft deterrent system operate correctly?

--

Go to Step 11

Go to Step 9

8

The content theft deterrent system is unable to sound the horn during an alarm event due to a malfunction with the vehicle horns. Refer to Diagnostic System Check - Horns in Horns.

Is the action complete?

--

Go to Step 12

--

9

  1. Inspect the BCM connector C2 terminal D10 for a poor terminal contact.
  2. If the connector is not faulty, replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Is the repair complete?

--

Go to Step 12

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10

Repair a poor connection or an open in circuit 28 between the BCM and the horn relay.

Is the repair complete?

--

Go to Step 12

--

11

The malfunction is not present at this time. Refer to Content Theft Deterrent (CTD) Circuit Description for more information.

Is the repair complete?

--

Go to Step 12

--

12

  1. Turn the ignition switch to the OFF position.
  2. Connect all of the connectors.
  3. Install any components that you removed.
  4. Turn the ignition switch to the RUN position for 6 seconds.
  5. Turn the ignition switch to the OFF position.
  6. Remove the MALL PGM fuse.
  7. Turn the ignition switch to the ACC position. The BCM flashes the fasten belts indicator and sounds the chime 4 times. The number of chimes identifies the BCM type installed on the vehicle.
  8. Within 1 second, turn the ignition switch from the ACC position to the OFF position and back to the ACC position. The BCM sounds any stored DTCs.

Are any BCM DTCs present?

--

Go to Diagnostic System Check - Body Control System in Body Control System

Go to Content Theft Deterrent (CTD) System Check