Cruze

Horns Malfunction

The BCM monitors the horn switch signal circuit, when the horn pad is pressed, the BCM detects the drop in the horn switch signal circuit and provides a ground for the Horn PCB relay within the underbonnet fuse block. The underbonnet fuse block will then provide B+ voltage to the horn control circuit, sounding the horn

A short to ground in the horn relay control circuit or a short to voltage in the horn control circuit will cause the horn to sound continuously until the horn overheats and become inoperative.

Rotate the steering wheel while pressing the horn pad to identify intermittent and poor connections within the steering column.

If diagnosing a Horn- Poor Tone condition, inspect the following:

Schematic Reference

Horn Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Horns System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the scan tool Horn Switch parameter while pressing and releasing the horn pad. The parameter should change from Inactive to Active.

⇒	If the value does not change, refer to Horn Switch Malfunction.

2. Command the Horn Relay Command ON and OFF with the scan tool, the P12 horn should turn ON and OFF when changing between the commanded states.

⇒	If the P12 horn is always ON or always OFF, refer to Horn Malfunction.

⇒	If the sound emitted from the P12 horn is not clear and even, refer to Horn - Poor Tone.

Horn Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the S33 horn switch.
2. Ignition ON, verify the scan tool Horn Switch parameter is Inactive.

⇒	If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K9 BCM.

3. Install a 3A fused jumper wire between the signal circuit terminal 1 and ground, verify the scan tool Horn Switch parameter is Active.

⇒	If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.

4. If all circuits test normal, test or replace the S33 horn switch.

Horn Malfunction

1. Ignition OFF, disconnect the harness connector at the P12 horn.
2. Test for less than 5 ohms between the ground circuit terminal A and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect the harness connector at the P12 horn.
4. Connect a 15 A fused jumper wire between the horn fuse test point and B+, the P12 horn should sound.

⇒	If the P12 horn does not sound, test the control circuit terminal 11 at the X50A underbonnet fuse block for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the P12 horn.

5. Disconnect the X5 harness connector at the K9 BCM.
6. Test for greater than 9V between the control circuit terminal 19 and ground.

⇒	If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the X50A underbonnet fuse block.

7. Connect a 15A fused jumper wire between the control circuit terminal 19 and ground, the P12 horn should sound.

⇒	If the horn does not sound, test the control circuit for a short to voltage. If the circuit tests normal, replace the X50D underbonnet fuse block.

8. If all circuits test normal, replace the K9 BCM.

Horn - Poor Tone

1. Ignition OFF, disconnect the harness connector at the P12 horn.
2. Test for less than 1 ohm between the ground circuit terminal A and ground.

⇒	If greater than the specified range, test the ground circuit for high resistance.

3. Disconnect the X1 harness connector at the X50A underbonnet fuse block.
4. Test for less than 1 ohm between the control circuit terminal 11 at the X50A underbonnet fuse block and the control circuit terminal B at the P12 horn.

⇒	If greater than the specified range, test the control circuit for high resistance.

5. If all circuits test normal, test or replace the P12 horn.

Horn Test

1. Ignition OFF, disconnect the harness connector at the P12 horn.
2. Install a 15A fused jumper wire between the control terminal B and 12V. Install a jumper wire between the ground terminal A and ground. Verify the P12 horn emits a clear and even tone.

⇒	If the sound emitted is not clear and even, replace the P12 horn.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.