GM Service Manual Online
For 1990-2009 cars only

Horns Always On

Step

Action

Value(s)

Yes

No

1

Were you sent here from the Horns Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Horns

2

Are the horns pulsating on/off simulating theft deterrent mode?

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Go to Theft Deterrent System Inoperative

Go to Step 3

3

  1. Disconnect the BCM connector C1.
  2. Turn the ignition switch to the ON position.

Do the horns sound?

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Go to Step 4

Go to Step 11

4

  1. Remove the HORN #36 Micro Relay from the underhood electrical center.
  2. Connect a DMM between the BCM connector C1 terminal B10 and ground.
  3. Test circuit 28 for continuity to ground at the BCM connector C1 terminal B10.

Is circuit 28 continuous to ground?

--

Go to Step 5

Go to Step 6

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.

  1. Remove the driver's side inflator module from the steering wheel.
  2. Disconnect the horn brush slip ring connector inside the steering wheel.
  3. DMM still connected between the BCM connector C1 terminal B10 and ground.

Is circuit 28 continuous to ground?

--

Go to Step 10

Go to Step 9

6

  1. HORN #36 Micro Relay still removed from the underhood electrical center.
  2. Turn the ignition switch to the ON position.

Are the horns sounding continuously?

--

Go to Step 7

Go to Step 8

7

Repair a short to voltage in circuit 29.

Is the repair complete?

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Go to Step 12

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8

Replace the HORN #36 Micro Relay. Refer to Horn Relay Replacement .

Is the repair complete?

--

Go to Step 12

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9

Replace the Horn Switch Assembly. Refer to Horn Switch Replacement - On Vehicle .

Is the repair complete?

--

Go to Step 12

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10

Repair short to ground in circuit 28.

Is the repair complete?

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Go to Step 12

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11

Replace the BCM. Refer to Body Control Module Replacement and Body Control Module (BCM) Programming/RPO Configuration .

Is the repair complete?

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Go to Step 12

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12

  1. Clear any DTCs which may have set.
  2. Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Diagnostic System Check - Horns