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 horn relay is part of the Smart Junction Box (SJB) and cannot be replaced independently. When the horn switch (part of the steering wheel) is pressed, the switch closes and ground is applied from the steering wheel harness through the clockspring to the horn relay through circuit CRH02 (BU/WH). The horn relay is then energized, applying voltage to the horn through circuit CBP14 (VT/OG), enabling the horn to sound.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Steering wheel harness
- 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 CIRCUIT CBP14 (VT/OG) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: SJB C2280e.
- Does the horn continue to sound?
Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
No
GO to B2.
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B2 CHECK THE HORN SWITCH INPUT
- Connect: SJB C2280e.
- Disconnect: SJB C2280c.
- 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. CLEAR the DTCs. REPEAT the self-test.
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B4 CHECK THE CLOCKSPRING FOR A SHORT TO GROUND
- Remove the driver air bag module.
- Connect: Clockspring C218a.
- Measure the resistance between the SJB C2280c-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. CLEAR the DTCs. REPEAT the self-test.
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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. CLEAR the DTCs. REPEAT the self-test.
No
REPAIR or INSTALL a new steering wheel harness. INSTALL the driver air bag module. CLEAR the DTCs. REPEAT the self-test.
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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.
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