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 Battery Junction Box (BJB) supplies the switched and control voltage to the horn relay (part of the Smart Junction Box (SJB)) through circuit SBB02 (YE/RD). When the horn switches (part of the steering wheel) are pressed, the horn relay is grounded through the horn switch circuitry, energizing the horn relay. The horn relay then sends voltage to the horn through circuit CBP05 (YE), sounding the horn. Ground for the horn is supplied through circuit GD123 (BK/GY).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Clockspring
- Steering wheel harness
- Horn switches (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 CBP05 (YE) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: SJB C2280a.
- 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
- Connect: SJB C2280a.
- Disconnect: SJB C2280b.
- 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 C218a.
- Measure the resistance between the clockspring C218a-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. Refer to Air Bag Systems.
- Connect: Clockspring C218a.
- Disconnect: Clockspring C218b.
- Measure the resistance between the SJB C2280b-6, 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. REFER to Air Bag Systems. TEST the system for normal operation.
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B5 CHECK THE STEERING WHEEL HARNESS FOR A SHORT TO GROUND
- Disconnect: Horn Switch C2296 and C2297.
- Measure the resistance between the clockspring 218b-1, circuit CRH02 (BU/WH), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
INSTALL a new steering wheel. INSTALL the driver air bag module. REFER to Air Bag Systems. TEST the system for normal operation.
No
REPAIR or INSTALL a new steering wheel harness. INSTALL the driver air bag module. REFER to Air Bag 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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