GM Service Manual Online
For 1990-2009 cars only

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step tests if ground is constantly being applied to the horn relay.

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Depress and release the horn switch.

Are the horns ON at all times?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3

Disconnect the body control module (BCM).

Are the horns ON at all times?

Go to Step 4

Go to Step 8

4

Disconnect the horn relay.

Are the horns ON at all times?

Go to Step 10

Go to Step 5

5

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 7

Go to Step 6

6

Inspect for poor connections at the horn relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 12

7

Repair the short to ground in the horn relay control circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 13

--

8

Test the horn switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 9

9

Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 11

10

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

Did you complete the repair?

Go to Step 13

--

11

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 13

--

12

Replace the horn relay.

Did you complete the replacement?

Go to Step 13

--

13

Operate the horns.

Do the horns operate properly?

System OK

Go to Step 1