GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - Horns

2

Remove the horn relay from the Underhood Fuse Block.

Does the horn continue to sound?

--

Go to Step 3

Go to Step 4

3

Repair the short to the voltage in the CKT 1329 (DK GRN) between the horn relay and the horns. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check - Horns

--

4

Connect a test lamp between terminal 1 and terminal 2 in the horn relay socket.

Does the test lamp light?

--

Go to Step 6

Go to Step 5

5

Replace the horn relay. Refer to Horn Relay Replacement .

Is the repair complete?

--

Go to Diagnostic System Check - Horns

--

6

  1. Disconnect the horn switches.
  2. Connect a test lamp between terminal 1 and terminal 2 in the horn relay socket.

Does the test lamp light?

--

Go to Step 7

Go to Step 8

7

  1. Disconnect the body control module (BCM).
  2. Connect a test light between terminal 1 and terminal 2 in the horn relay socket.

Does the test lamp light?

--

Go to Step 9

Go to Step 10

8

Replace the horn switch. Refer to Horn Switch Replacement - On Vehicle .

Is the repair complete?

--

Go to Diagnostic System Check - Horns

--

9

Repair the short to ground in the CKT 28 (BLK) between the horn relay and the horn switch or the BCM. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check - Horns

--

10

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

Is the repair complete?

--

Go to Diagnostic System Check - Horns

--