Pinpoint Test D: The Horn Is Always On - Stripped Chassis

Horn

Pinpoint Tests

Pinpoint Test D: The Horn Is Always On - Stripped Chassis

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

Normal Operation

The Battery Junction Box (BJB) supplies the control and switched voltage to the horn relay. When the horn pad is pressed, the horn switch supplies ground through the clockspring to the horn relay. The horn relay is then energized routing voltage to the horn, enabling the horn to sound.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- Horn relay
- Clockspring
- Steering wheel harness
- Horn switch


PINPOINT TEST D: THE HORN IS ALWAYS ON - STRIPPED CHASSIS

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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D1 CHECK THE HORN RELAY OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE


- Ignition OFF.
- Disconnect: Horn Relay.
- 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 D2.

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D2 CHECK THE HORN SWITCH INPUT


- Substitute a known good relay.
- Does the horn continue to sound?

Yes
REMOVE the known good relay. GO to D3.

No
REMOVE the known good relay. INSTALL a new horn relay. TEST the system for normal operation.

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D3 CHECK THE HORN RELAY COIL GROUND CIRCUIT FOR A SHORT TO GROUND


- Disconnect: Clockspring C218.
- Measure the resistance between the clockspring C218-3, circuit CRH02 (BU/WH), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to D4.

No
REPAIR circuit CRH02 (BU/WH) for a short to ground. TEST the system for normal operation.

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D4 CHECK THE CLOCKSPRING FOR A SHORT TO GROUND


- Remove the horn switch. Refer to Horn Switch Service and Repair.
- Connect: Clockspring C218.
- Measure the resistance between the horn relay pin 2, circuit CRH02 (BU/WH), BJB face side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to D5.

No
INSTALL a new clockspring. REFER to Supplemental Restraint System Service and Repair. TEST the system for normal operation.

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D5 CHECK THE STEERING WHEEL HARNESS FOR DAMAGE OR SHORTS


- Inspect the steering wheel harness for damage or shorts.
- Is the steering wheel harness OK?

Yes
INSTALL a new horn switch. REFER to Horn Switch Service and Repair. TEST the system for normal operation.

No
REPAIR or INSTALL a new steering wheel harness. INSTALL the horn switch. REFER to Horn Switch Service and Repair. TEST the system for normal operation.

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