GM Service Manual Online
For 1990-2009 cars only

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Tests if ground is constantly being applied to the horn relay.

  2. The horn relay control circuit includes the horn slip ring and the horn switch. The horn switch is part of the inflatable restraint steering wheel module. The horn slip ring and the horn switch must be tested for a short to ground.

Step

Action

Yes

No

1

Is the vehicle equipped with content theft deterrent (UA6)?

Go to Step 2

Go to Step 3

2

Did you perform the Horns Diagnostic System Check?

Go to Step 4

Go to Diagnostic System Check - Horns

3

Did you review the Horns operation and perform the necessary inspections?

Go to Step 4

Go to Symptoms - Horns

4

Depress and release the horn switch.

Are the horns on at all times?

Go to Step 5

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

5

Is the vehicle equipped with content theft deterrent (UA6)?

Go to Step 6

Go to Step 7

6

Disconnect the body control module (BCM).

Are the horns on at all times?

Go to Step 7

Go to Step 11

7

Disconnect the horn relay.

Are the horns on at all times?

Go to Step 12

Go to Step 8

8

Connect a test lamp between the battery positive voltage circuit of the horn relay coil and the horn relay control circuit.

Does the test lamp illuminate?

Go to Step 10

Go to Step 9

9

Inspect for poor connections at the horn relay. 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 15

Go to Step 14

10

Important:: The horn switch is part of the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement in SIR.

To disable the SIR system, refer to Disabling the SIR System in SIR.

Repair the short to ground in the horn relay control circuit. (The horn relay control circuit includes the horn slip ring and the horn switch.) Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 15

--

11

Inspect for poor connections at the harness connector of 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 15

Go to Step 13

12

Repair the short to voltage in the horn control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 15

--

13

Important:: Perform the BCM programming procedure when replacing the BCM.

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

Did you complete the replacement?

Go to Step 15

--

14

Replace the horn relay.

Did you complete the replacement?

Go to Step 15

--

15

Operate the horns.

Do the horns operate properly?

System OK

Go to Step 1