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

Inspect the HORN fuse.

Is the HORN fuse open?

--

Go to Step 3

Go to Step 4

3

Repair the short to ground in CKT 1329 (DK GRN) or horns. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check - Horns

--

4

  1. Remove the horn relay from the Underhood Fuse Block.
  2. Connect a test lamp from ground to CKT 42 cavity 1 and cavity 3 of the horn relay socket.

Does the test lamp light in both positions?

--

Go to Step 6

Go to Step 5

5

Replace the Underhood Fuse Block. Refer to Underhood Fuse Block Replacement in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check - Horns

--

6

  1. Reinstall the horn relay.
  2. Connect a fused jumper from the Underhood Fuse Block connector C1 cavity E3 to ground.

Does the horn sound?

--

Go to Step 8

Go to Step 7

7

Replace the Horn Relay. Refer to Horn Relay Replacement .

Is the repair complete?

--

Go to Diagnostic System Check - Horns

--

8

Connect a fused jumper from Body harness side connector C211 cavity A11 to ground.

Does the horn sound?

--

Go to Step 9

Go to Step 10

9

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

Is the repair complete?

--

Go to Diagnostic System Check - Horns

--

10

  1. Disconnect the BCM connector C1.
  2. Connect a fused jumper from harness side connector cavity A9, CKT 28 (BLK) to ground.

Does the horn sound?

--

Go to Step 11

Go to Step 12

11

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

Is the repair complete?

--

Go to Diagnostic System Check - Horns

--

12

Locate and repair open in CKT 28 (BLK). Refer to Wiring Repairs in Wiring Systems.

Is repair complete?

--

Go to Diagnostic System Check - Horns

--