Horn - Horn
Mondeo 2007.5 (02/2007-)
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Diagnosis and Testing
Principles of Operation
The horn system consists of a relay, a steering wheel switch and either one or two horns. The horn(s) receives voltage from the switched side of the relay,
and the relay switch is controlled on its ground side by the steering wheel switch.
The horn relay, is located in the battery junction box (BJB) and is supplied with a permanent voltage from the battery.
The steering wheel horn switch shares the steering wheel clockspring circuit with the air-bag circuit. Each of these systems work completely independent of
each other.
Inspection and Verification
1.
1. Verify the customer concern.
2.
2. Visually inspect for obvious signs of mechanical or electrical damage.
Visual Inspection Chart
3.
3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
4.
4. Retrieve the Diagnostic Trouble Code (DTC)s and refer to the DTC Index Chart.
Diagnostic Trouble Code (DTC) Index Chart
1.
1. If the cause is still evident, refer to the Symptom Chart.
Symptom Chart
Pinpoint Tests
Electrical
Fuse(s)
Wiring harness
Electrical connector(s)
Horn switch
Horn
Clockspring
Horn relay
BJB
DTC
Description/Condition
Possible Source
Action
9C5512
Horn relay- circuit short to battery
BJB
REFER to Ford diagnostic equipment.
9C5514
Horn relay - circuit short to ground or open
BJB
REFER to Ford diagnostic equipment.
Symptom
Possible Sources
Action
The horn is inoperative
Circuit(s).
Horn.
Horn relay.
Clockspring.
Horn switch.
BJB.
*
*
*
*
*
*
GO to Pinpoint Test
A.
*
The horn is always on
Horn relay.
BJB.
Horn switch.
Circuit(s).
Clockspring.
*
*
*
*
*
REFER to the Ford diagnostic equipment.
*
PINPOINT TEST A : THE HORN IS INOPERATIVE
TEST CONDITIONS
DETAILS/RESULTS/ACTIONS
A1: CHECK POWER TO THE HORN
Disconnect Horn C1RH02.
1
Measure the voltage between the horn C1RH02 pin 2, circuit GBB31B (BU/OG), harness side and ground while
pressing the horn switch.
2
Is the voltage greater than 10 volts?
Yes
GO to A2
.
No
GO to A3
.
A2: CHECK GROUND TO THE HORN
Measure the resistance between the horn C1RH02 pin 1, circuit GD312G (BK/VT), harness side and ground.
1
Is the resistance less than 5 ohms?
Yes
INSTALL a new horn. TEST the system for normal operation.
No
REPAIR circuit GD312G (BK/VT). TEST the system for normal operation.
A3: CHECK POWER TO THE HORN RELAY
Disconnect Horn Relay R9.
1
Measure the voltage between the horn relay R9 pin 1, harness side and ground; and horn relay R9 pin 3, harness side
and ground.
2
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Are the voltages greater than 10 volts?
Yes
GO to A4
.
No
INSTALL a new BJB. TEST the system for normal operation.
A4: CHECK HORN SWITCH CIRCUIT FOR OPEN
Measure the resistance between the horn relay R9 pin 2, circuit CRH04A (VT/GN), harness side and ground while
pressing the horn switch.
1
Is the resistance less than 5 ohms?
Yes
INSTALL a new horn Relay R9. Test the system for normal operation.
No
GO to A5
.
A5: CHECK SUPPLY TO THE CJB
Disconnect CJB 1BB01.
1
Measure the voltage between the CJB 1BB01 pin 1, harness side and ground and between the CJB 1BB01 pin 2,
harness side and ground.
2
Are the voltages greater than 10 volts?
Yes
REPAIR the circuit SBB17. TEST the system for normal operation.
No
GO to A6
.
A6: CHECK CIRCUIT CRH04A (BN) FOR OPEN
Measure the resistance between the CJB 1BB01 pin 46 component side and ground while pressing the horn switch.
1
Is the resistance less than 5 ohms?
Yes
REPAIR the circuit CRH04A. TEST the system for normal operation.
No
GO to A7
.
A7: CHECK CJB 1BB01 FOR OPEN
Measure the resistance between the CJB 1BB01 pin 13, harness side and ground while pressing the horn switch.
1
Is the resistance less than 5 ohms?
Yes
INSTALL a new CJB 1BB01. Test the system for normal operation.
No
GO to A8
.
A8: CHECK CIRCUIT CRH03A (BN) FOR OPEN
WARNING: To deactivate the driver air bag, refer to the procedure in section 501-20B. Failure to follow this instruction, may result in personal
injury.
Disconnect steering wheel module 2R115.
1
Measure the resistance between the steering wheel module 2R115 pin 4, circuit CRH03-A (BN), harness side and horn
relay R9 pin 2, CRH03-A (BN), harness side.
2
Is the resistance less than 5 ohms?
Yes
GO to A9
.
No
REPAIR the circuit CRH03-A. TEST the system for normal operation.
A9: CHECK CIRCUIT GD133CJ (BK) FOR OPEN
Measure the resistance between the steering wheel module 2R115 pin 7, circuit GD133CJ (BK), harness side and
1
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ground.
Is the resistance less than 5 ohms?
Yes
GO to A10
.
No
REPAIR the circuit GD133CJ. TEST the system for normal operation.
A10: CHECK CIRCUIT C2RH02AB FOR OPEN
Disconnect horn switch 2RH03.
1
Measure the resistance between the steering wheel module 2R115 pin 7, circuit CRH02AB, harness side and horn
switch 2RH03 pin 1, circuit C2RH02B, harness side.
2
Is the resistance less than 5 ohms?
Yes
GO to A11
.
No
REPAIR the circuit C2RH02AB. TEST the system for normal operation.
A11: CHECK THE HORN SWITCH
Measure the resistance between the horn switch 2RH03 pin 1, component side and horn switch 2RH03 pin 2,
component side while pressing the horn switch.
1
Is the resistance less than 5 ohms?
Yes
GO to A12
.
No
INSTALL a new horn switch 2RH03. TEST the system for normal operation.
A12: CHECK CIRCUIT C2RH03AB FOR OPEN
Measure the resistance between the steering wheel module pin 4, circuit CRH03AB, harness side and horn switch
C2RH03 pin 2, circuit C2RH03AB, harness side.
1
Is the resistance less than 5 ohms?
Yes
INSTALL a new steering wheel module. TEST the system for normal operation.
No
REPAIR the circuit C2RH03AB. TEST the system for normal operation.
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