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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