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 (part of the SJB). When the horn switch (part of the steering wheel) is pressed, the switch is grounded through circuit GD114 (BK/BU). Ground is then supplied to the horn relay through circuit CRH02 (BU/WH), energizing the horn relay. The horn relay then sends voltage to the horn through circuit SRH01 (YE/RD), enabling the horn to sound. Ground for the horn is supplied through circuit GD123 (BK/GY).
Possible Causes
- 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 CIRCUIT SRH01 (YE/RD) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: SJB C2280e.
- Does the horn continue to sound?
Yes
REPAIR the circuit. 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 CIRCUIT CRH02 (BU/WH) FOR A SHORT TO GROUND
- Depower the Supplemental Restraint System (SRS). Refer to Air Bag Systems.
- Disconnect: Clockspring C218.
- Measure the resistance between the clockspring C218-8, circuit CRH02 (BU/WH), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to B4.
No
REPAIR the circuit. REPOWER the SRS. REFER to Air Bag 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.
- Connect: Clockspring C218.
- 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. INSTALL the driver air bag module. TEST the system for normal operation.
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B5 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 steering wheel. TEST the system for normal operation.
No
INSTALL a new steering wheel harness. 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. 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. TEST the system for normal operation.
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