GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2000 🢒 LeSabre 🢒 Body and Accessories 🢒 Theft Deterrent 🢒 Horns Inoperative

Test Description

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

  1. Listen for an audible click when the horn relay operates. Command both the ON and OFF states. Repeat the commands as necessary.

    2.

  2. This step tests for voltage at the coil side of the horn relay.

    3.

  3. This step verifies that the dash integration module (DIM) is providing ground to the horn relay.

    4.

  4. The control circuit includes the horn switch which is part of the steering wheel module inflatable restraint. The switch must be tested for a high resistance, an open, or a short to B+ when testing the relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems and Inflatable Restraint Steering Wheel Module Replacement in SIR.

  5. This step tests for voltage at the feed side of the horn relay. The HORN fuse supplies power to the feed side of the horn relay.

    6.

  6. The horns need maximum current flow in order to operate properly. Inspect the circuits for faults that might restrict current flow.

Step

Action

Value(s)

Yes

No

1

Did you preform the Horns Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Horns

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Using a scan tool, command the dash integration module (DIM) horn output ON and OFF.
  4. Activate the horn switch.

Does the horn relay turn ON and OFF both with each command of the scan tool and horn switch?

--

Go to Step 9

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the horn relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the coil side feed circuit of the horn relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 4

Go to Step 7

4

  1. Connect a test lamp between the control circuit of the horn relay and the coil side feed circuit of the horn relay.
  2. Using a scan tool, command the DIM horn output ON and OFF.
  3. Activate the horn switch.

Does the test lamp turn ON and OFF both with each command of the scan tool and horn switch?

--

Go to Step 13

Go to Step 5

5

Caution: When you are performing service on or near the SIR components or the SIR wiring, you must disable the SIR system. Refer to Disabling the SIR System. Failure to follow the correct procedure could cause air bag deployment, personal injury, or unnecessary SIR system repairs.

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

  1. Disable the SIR system. Refer to Disabling the SIR System in SIR.
  2. Test the control circuit of the horn relay for a high resistance, an open or a short to B+. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 6

6

Inspect for poor connections at the harness connector of the DIM. 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 20

Go to Step 8

7

Repair the coil side feed circuit of the horn relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

--

8

Replace the DIM. Refer to Dash Integration Module Replacement in Body Control System.

Did you complete the replacement?

--

Go to Step 20

--

9

  1. Turn OFF the ignition.
  2. Disconnect the horn relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the feed circuit of the horn relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 10

10

Repair the feed circuit of the horn relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

--

11
  1. Turn OFF the ignition.
  2. Reconnect the horn relay.
  3. Disconnect the horn assembly.
  4. Turn ON the ignition, with the engine OFF.
  5. Probe the feed circuit of the horn assembly with a test lamp that is connected to a good ground.
  6. With a scan tool, command the horn relay ON.

Does the test lamp illuminate?

--

Go to Step 15

Go to Step 12

12

Test the feed circuit of the dual horn assembly for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 15

13

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 20

Go to Step 14

14

Replace the horn relay. Refer to Horn Relay Replacement .

Did you complete the replacement?

--

Go to Step 20

--

15

Test the ground circuit of the horn assembly for a high resistance or an a open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 16

16

Inspect for poor connections at the horn assembly. 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 20

Go to Step 17

17
  1. Connect a 15 amp fused jumper wire between battery (B+) and the horn assembly input.
  2. Connect another jumper wire between battery (B-) and the horn assembly ground.

Do the horns sound?

--

Go to Step 18

Go to Step 19

18

Test the feed and ground circuits of the horn assembly for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 19

19

Replace the horn assembly. Refer to Horn Replacement .

Did you complete the replacement?

--

Go to Step 20

--

20

Operate the vehicle within the Conditions for Running the symptom.

Does the symptom reoccur?

--

Go to Step 1

System OK