GM Service Manual Online
For 1990-2009 cars only

Test Description

The numbers below refer to the step numbers on the diagnostic table.

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

  2. The horn relay control circuit includes the horn switch. The horn switch must be tested for a short to ground when testing the relay control circuit.

Step

Action

Yes

No

Schematic Reference: Horn Schematics

Connector End View: Horn Connector End Views

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 horn relay.

Are the horns ON at all times?

Go to Step 7

Go to Step 4

4

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 6

Go to Step 5

5

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 9

Go to Step 8

6

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 9

--

7

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

Did you complete the repair?

Go to Step 9

--

8

Replace the horn relay. Refer to Relay Replacement .

Did you complete the replacement?

Go to Step 9

--

9

Operate the horns.

Do the horns operate properly?

System OK

Go to Step 1