Pinpoint Test B: The Horn Is Always On

Horn

Pinpoint Tests


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 Smart Junction Box (SJB) supplies the switched and control voltage to the horn relay (integrated into the SJB). When the horn switch (part of the steering wheel) is pressed, the switch is grounded to the steering wheel. Ground is then supplied to the horn relay, energizing the horn relay. The horn relay then sends 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 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 POWER SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE


- Ignition OFF.
- Disconnect: SJB 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.

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B2 CHECK THE HORN SWITCH INPUT


- Disconnect: SJB C2280b.
- Connect: SJB C2280e.
- Does the horn continue to sound?

Yes
GO to B6.

No
GO to B3.

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B3 CHECK THE HORN RELAY COIL GROUND CONTROLLED CIRCUIT FOR A SHORT TO GROUND


- Depower the Supplemental Restraint System (SRS). Refer to Restraint Systems.
- Disconnect: Clockspring C2274.
- Measure the resistance between the clockspring C2274-8, circuit CRH02 (BU/WH), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to B4.

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

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B4 CHECK THE CLOCKSPRING FOR A SHORT TO GROUND


- Remove the driver air bag module. Refer to Restraint Systems.
- Connect: Clockspring C2274.
- Disconnect: Upper Clockspring .
- Measure the resistance between the SJB C2280b-41, circuit CRH02 (BU/WH), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to B5.

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

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B5 CHECK THE STEERING WHEEL HARNESS FOR A SHORT


- Remove the driver air bag module. Refer to Restraint Systems.
- Disconnect: Upper Clockspring .
- Disconnect: Horn Switch .
- Inspect the steering wheel harness for shorts.
- Is the steering wheel harness OK?

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

No
REPAIR or INSTALL a new steering wheel harness. INSTALL the driver air bag module. REFER to Restraint Systems. TEST the system for normal operation.

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B6 CHECK FOR CORRECT SJB OPERATION


- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB 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 SJB. REFER to Body Control Systems. 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.

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