Pinpoint Test C: The Horn Is Inoperative - Stripped Chassis
Horn
Pinpoint Tests
Pinpoint Test C: The Horn Is Inoperative - Stripped Chassis
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 control and switched voltage to the horn relay. When the horn pad is pressed, the horn switch supplies ground through the clockspring to the horn relay. The horn relay is then energized routing voltage to the horn, enabling the horn to sound.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Horn relay
- Horn
- Clockspring
- Steering wheel harness
- Horn switch
PINPOINT TEST C: THE HORN IS INOPERATIVE - STRIPPED CHASSIS
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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C1 CHECK THE HORN RELAY
- Ignition OFF.
- Disconnect: Horn Relay.
- Substitute a known good relay and recheck the horn operation.
- Does the horn operate correctly?
Yes
REMOVE the known good relay. INSTALL a new horn relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to C2.
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C2 CHECK FOR VOLTAGE TO THE HORN RELAY
- Measure the voltage between the horn relay pin 3, circuit SBB34 (YE/RD), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to C3.
No
VERIFY the BJB fuse 34 (20A) is OK. If OK, REPAIR circuit SBB34 (YE/RD) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
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C3 CHECK FOR VOLTAGE TO THE HORN RELAY COIL
- Measure the voltage between the horn relay pin 1, circuit SBB34 (YE/RD), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to C4.
No
REPAIR circuit SBB34 (YE/RD) for an open. TEST the system for normal operation.
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C4 BYPASS THE HORN RELAY
- Connect a fuse jumper wire between the horn relay pin 3, circuit SBB34 (YE/RD), BJB face side and the horn relay pin 5, circuit SRH01 (YE/RD), BJB face side.
- Does the horn sound?
Yes
REMOVE the jumper wire. GO to C7.
No
LEAVE the jumper wire connected. GO to C5.
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C5 CHECK FOR VOLTAGE TO THE HORN
- Ignition OFF.
- Disconnect: Horn C131.
- Measure the voltage between the horn C131-2, circuit SRH01 (YE/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
LEAVE the jumper wire connected. GO to C6.
No
REMOVE the jumper wire. REPAIR circuit SRH01 (YE/RD) for an open. TEST the system for normal operation.
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C6 CHECK FOR VOLTAGE TO THE HORN USING THE CONNECTOR GROUND
- Measure the voltage between the horn C131-2, circuit SRH01 (YE/RD), harness side and the horn C131-1, circuit GD122 (BK), harness side.
- Is the voltage greater than 10 volts?
Yes
REMOVE the jumper wire. INSTALL a new horn. REFER to Horn Service and Repair. TEST the system for normal operation.
No
REMOVE the jumper wire. REPAIR circuit GD122 (BK) for an open. TEST the system for normal operation.
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C7 CHECK FOR VOLTAGE TO THE CLOCKSPRING
- Connect: Horn Relay.
- Disconnect: Clockspring C218.
- Measure the voltage between the clockspring C218-3, circuit CRH02 (BU/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to C8.
No
REPAIR circuit CRH02 (BU/WH) for an open. TEST the system for normal operation.
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C8 CHECK FOR VOLTAGE TO THE CLOCKSPRING USING THE CONNECTOR GROUND
- Measure the voltage between the clockspring C218-3, circuit CRH02 (BU/WH), harness side and the clockspring C218-4, circuit GD114 (BK/BU), harness side.
- Is the voltage greater than 10 volts?
Yes
GO to C9.
No
REPAIR circuit GD114 (BK/BU) for an open. TEST the system for normal operation.
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C9 CHECK THE CLOCKSPRING FOR AN OPEN
- Remove the horn switch. Refer to Horn Switch Service and Repair.
- Disconnect: Upper Clockspring Connector.
- Measure the resistance between the clockspring C218 pin 3, component side and the upper clockspring connector pin 3, component side.
- Measure the resistance between the clockspring C218 pin 4, component side and the upper clockspring pin 2, component side.
- Are the resistances less than 5 ohms?
Yes
GO to C10.
No
INSTALL a new clockspring. REFER to Supplemental Restraint System Service and Repair. TEST the system for normal operation.
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C10 CHECK THE STEERING WHEEL HARNESS
- Inspect the steering wheel harness for damage or opens.
- Is the steering wheel harness OK?
Yes
INSTALL a new horn switch. REFER to Horn Switch Service and Repair. TEST the system for normal operation.
No
REPAIR or INSTALL a new steering wheel harness. INSTALL the horn switch. REFER to Horn Switch Service and Repair. TEST the system for normal operation.
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