Pinpoint Test B: The Horn Is Always On

Horn

Pinpoint Test

Pinpoint Test B: The Horn Is Always On

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

Normal Operation

The horn relay control voltage and the horn relay switched voltage circuits are supplied by the Smart Junction Box (SJB) fuse 13 (15A). The horn relay (integrated into the SJB) is controlled through the clockspring to the horn switch (part of the steering wheel). When the horn switch is pressed, the horn relay is grounded through the steering wheel switch harness (part of the steering wheel). The horn relay is then energized, enabling the horn to sound.

- DTC B1897 (Horn Switch Circuit Failure) - a continuous and on-demand DTC that sets when the SJB detects a short to ground from the horn switch input circuit.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- Clockspring
- Horn switch (part of the steering wheel)
- SJB



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.

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B1 CHECK THE HORN INPUT CIRCUIT FOR A SHORT TO VOLTAGE


- Ignition OFF.
- Disconnect: SJB C2280a.
- Ignition ON.
- Does the horn continue to sound?

Yes
REPAIR circuit CRH02 (BU/WH) for a short to voltage. TEST the system for normal operation.

No
GO to B2.

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B2 CHECK THE SJB FOR INTERNAL FAULTS


- Ignition OFF.
- Connect: SJB C2280a.
- Disconnect: SJB C2280d.
- Ignition ON.
- Does the horn continue to sound?

Yes
INSTALL a new SJB. REFER to Body Control Systems. TEST the system for normal operation.

No
GO to B3.

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B3 CHECK THE CLOCKSPRING INPUT CIRCUIT FOR A SHORT TO GROUND


- Ignition OFF.
- Connect: SJB C2280d.
- Disconnect: Clockspring C218a.
- Does the horn continue to sound?

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

No
GO to B4.

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B4 CHECK THE CLOCKSPRING FOR A SHORT TO GROUND


- Remove the driver air bag. Refer to Restraint Systems.
- Disconnect: Upper Clockspring C218c.
- Connect: Clockspring C218a.
- Measure the resistance between the upper clockspring C218c pin 5, component side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
INSTALL a new steering wheel. REFER to Steering Column. TEST the system for normal operation.

No
INSTALL a new clockspring. REFER to Restraint Systems. TEST the system for normal operation.

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