Pinpoint Test B: The Horn Is Always On

Horn

Pinpoint Test B: The Horn Is Always On

Refer to Wiring Diagram Set 44, Horn/Cigar Lighter for schematic and connector information Electrical Diagrams.

Normal Operation

When the driver air bag module is pressed, the normally open horn switch (part of the steering wheel) is closed and ground is routed through the clockspring and the Steering Column Control Module (SCCM) to the horn relay, energizing the horn relay. The Body Control Module (BCM) supplies the switched and control voltage to the horn relay, which is integrated into the BCM (Body Control Module). The horn relay then provides voltage to the horn, enabling the horn to sound.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- Clockspring

- Steering wheel harness

- Horn switches (part of the steering wheel)

- BCM (Body Control Module)

- SCCM (Steering Column Control Module)

PINPOINT TEST B : THE HORN IS ALWAYS ON

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

B1 CHECK THE BCM (Body Control Module) HORN OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: BCM (Body Control Module) C2280E.

Does the horn continue to sound?

Yes
REPAIR circuit SRH01 (YE/RD) for a short to voltage. TEST the system for normal operation.

No
GO to B2.

B2 CHECK THE HORN SWITCH INPUT TO THE BCM (Body Control Module)

- Connect: BCM (Body Control Module) C2280E.

- Disconnect: BCM (Body Control Module) C2280B.

Does the horn continue to sound?

Yes
GO to B7.

No
GO to B3.

B3 CHECK THE HORN SWITCH INPUT FOR A SHORT TO GROUND

- Connect: BCM (Body Control Module) C2280B.

- Disconnect: SCCM (Steering Column Control Module) C2414A.

Does the horn continue to sound?

Yes
REPAIR circuit CRH04 (VT/GN) for a short to ground. TEST the system for normal operation.

No
GO to B4.

B4 CHECK THE HORN SWITCH

- Connect: SCCM (Steering Column Control Module) C2414A.

- Remove the driver air bag module.

- Disconnect: Horn Switch C217A.

Does the horn continue to sound?

Yes
GO to B5.

No
INSTALL a new steering wheel. TEST the system for normal operation.

B5 CHECK THE STEERING WHEEL HARNESS

- Disconnect: Clockspring C218B.

Does the horn continue to sound?

Yes
GO to B6.

No
The steering wheel harness has a short circuit.

INSTALL a new steering wheel. TEST the system for normal operation.

B6 CHECK THE CLOCKSPRING FOR A SHORT TO GROUND

- Remove the clockspring.

Does the horn continue to sound?

Yes
GO to B8.

No
INSTALL a new clockspring. TEST the system for normal operation.

B7 CHECK FOR CORRECT BCM (Body Control Module) OPERATION

- Disconnect all the BCM (Body Control Module) connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all the BCM (Body Control Module) connectors and make sure they seat correctly.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new BCM (Body Control Module). TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

B8 CHECK FOR CORRECT SCCM (Steering Column Control Module) OPERATION

- Disconnect all the SCCM (Steering Column Control Module) connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all the SCCM (Steering Column Control Module) connectors and make sure they seat correctly.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new SCCM (Steering Column Control Module). TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. RUN the on-demand self-test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation.