GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2005 🢒 Yukon XL - 2WD 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Horns Inoperative - One Horn

Test Description

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

  1. The horns need maximum current flow to operate properly. A high resistance, greater than 0.5 ohm, in the horn control circuit or the horn ground circuit could cause operating problems with the horns. Inspect the circuits for faults that would restrict current flow.

Step

Action

Yes

No

DEFINITION: This diagnostic procedure is for use with systems that have multiple horns in which one of the horns is inoperative.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Depress the horn switch.

Do all of the horns operate?

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

Go to Step 3

3
  1. Disconnect the inoperative horn.
  2. Connect a test lamp between the horn control circuit and a good ground.
  3. Depress and hold the horn switch.

Does the test lamp illuminate?

Go to Step 4

Go to Step 7

4
  1. Connect a test lamp between the horn control circuit and the horn ground circuit.
  2. Depress and hold the horn switch.

Does the test lamp illuminate?

Go to Step 5

Go to Step 8

5

Inspect for poor connections at the inoperative horn. 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 11

Go to Step 6

6
  1. Connect a 15-amp fused jumper wire between the positive battery terminal and the control terminal of the horn.
  2. Connect another jumper wire between the negative battery terminal and the ground terminal of the horn.

Does the horn sound?

Go to Step 9

Go to Step 10

7

Repair the open or poor connection in the horn control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 11

--

8

Repair the open or poor connection in the horn ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 11

--

9

Repair the high resistance in the horn control circuit or the horn ground circuit of the horn. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 11

--

10

Replace the inoperative horn. Refer to Horn Replacement - Left Side and Horn Replacement - Right Side .

Did you complete the replacement?

Go to Step 11

--

11

Operate the horns.

Do the horns operate properly?

System OK

Go to Step 1