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 Central Junction Box (CJB) supplies the switched and control voltage to the horn relay (part of the Generic Electronic Module (GEM)). When the horn switch is pressed, the switch closes and ground is applied from the steering wheel harness through the clockspring to the horn relay. The horn relay is then energized, applying voltage to the horn, enabling the horn to sound.

The Tire Pressure Monitoring System (TPMS) module is also wired to the horn relay coil controlled circuit. The TPMS module sounds the horn during TPMS sensor training.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- Steering wheel harness
- Clockspring
- Driver air bag module
- GEM
- TPMS module



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 HORN POWER SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE


- Ignition OFF.
- Disconnect: GEM C201c.
- Does the horn continue to sound?

Yes
REPAIR circuit 29-GJ6 (OG/YE) for a short to voltage. TEST the system for normal operation.

No
GO to B2.

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B2 CHECK THE TPMS MODULE


- Connect: GEM C201c.
- Disconnect: TPMS Module C2409b.
- Does the horn continue to sound?

Yes
GO to B3.

No
GO to B8.

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B3 ISOLATE THE GEM


- Disconnect: GEM C201b.
- Connect: GEM C201c.
- Does the horn continue to sound?

Yes
GO to B7.

No
GO to B4.

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B4 CHECK THE HORN SWITCH INPUT CIRCUIT FOR A SHORT TO GROUND


- Depower the Supplemental Restraint System (SRS). Refer to Restraint Systems.
- Disconnect: Clockspring C218.
- Measure the resistance between the clockspring C218-6, circuit 31S-JG5 (BK/BU), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to B5.

No
REPAIR the horn switch input circuit for a short to ground. TEST the system for normal operation.

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B5 CHECK THE HORN CONTACT BAR FOR DAMAGE


- Remove the driver air bag module. Refer to Restraint Systems.
- Inspect the horn contact bar for damage.
- Is the horn contact bar OK?

Yes
GO to B6.

No
INSTALL a new driver air bag module. REFER to Restraint Systems. TEST the system for normal operation.

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B6 CHECK THE STEERING WHEEL HARNESS FOR SHORTS


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

Yes
INSTALL a new clockspring. REFER to Restraint Systems. 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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B7 CHECK FOR CORRECT GEM OPERATION


- Disconnect all the GEM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the GEM 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 GEM. 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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B8 CHECK FOR CORRECT TPMS MODULE OPERATION


- Disconnect all the TPMS module connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the TPMS module 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 TPMS module. REFER to Wheels and Tires. 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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