Ford Workshop Service and Repair Manuals

Refer to Wiring Diagrams Section 413-06, for schematic and connector information.

Inspection and Verification

Visual Inspection Chart

Symptom Chart

Symptom	Possible Sources	Action
The horn is inoperative	* Fuse(s). * Circuit(s). * Horn switch. * Horn. * Clockspring. * GEM.	* GO to Pinpoint Test A.
The horn is always on	* Clockspring. * Horn switch. * Circuit(s). * GEM.	* GO to Pinpoint Test B.

Pinpoint Tests

NOTE:Use a digital multimeter for all electrical measurements.

PINPOINT TEST A : THE HORN IS INOPERATIVE
TEST CONDITIONS	DETAILS/RESULTS/ACTIONS
A1: CHECK THE HORN FOR POWER
	1 Disconnect Horn C413 - All Except Vehicles with 2.0L Duratec-HE (MI4) engine or 1.6L Duratorq-TDCi (DV) Diesel engine.
	2 Disconnect Horn C414 - Vehicles with 2.0L Duratec-HE (MI4) engine or 1.6L Duratorq-TDCi (DV) Diesel engine.
	3 Measure the voltage between the horn C413 pin 1 or C414 pin 1, circuit 29S-GJ6 (OG/YE), harness side and ground while pressing the horn switch.
	Is the voltage greater than 10 volts? Yes All Except Vehicles with 2.0L Duratec-HE (MI4) engine or 1.6L Duratorq-TDCi (DV) Diesel engine, INSTALL a new horn. TEST the system for normal operation. Vehicles with 2.0L Duratec-HE (MI4) engine or 1.6L Duratorq-TDCi (DV) Diesel engine, GO to A2. No GO to A3.
A2: CHECK THE HORN GROUND CIRCUIT 31-GJ6 (BK)
	1 Measure the resistance between the horn C414 pin 2, circuit 31-GJ6 (BK), harness side and ground.
	Is the resistance less than 5 ohms? Yes INSTALL a new horn. TEST the system for normal operation. No REPAIR the circuit. TEST the system for normal operation.
A3: CHECK CIRCUIT 29S-GJ6 (OG/YE) FOR OPEN CIRCUIT
	1 Disconnect GEM C317.
	2 Measure the resistance between the GEM C317 pin 3, circuit 29S-GJ6 (OG/YE), harness side and the horn C413 pin 1 or C414 pin 1, circuit 29S-GJ6 (OG/YE), harness side.
	Is the resistance less than 5 ohms? Yes GO to A4. No REPAIR the circuit. TEST the system for normal operation.
A4: CHECK THE GEM FOR POWER
	1 Measure the voltage between the GEM C317 pin 4, circuit 29-GJ8 (OG), harness side and ground.
	Is the voltage greater than 10 volts? Yes GO to A5. No REPAIR circuit 29-GJ8 (OG). TEST the system for normal operation.
A5: CHECK THE GEM GROUND CIRCUIT 31-DK20 (BK)
	1 Disconnect GEM C318.
	2 Measure the resistance between the GEM C318 pin 3, circuit 31-DK20 (BK), harness side and ground.
	Is the resistance less than 5 ohms? Yes GO to A6. No REPAIR the circuit. TEST the system for normal operation.
A6: CHECK THE HORN SWITCH CIRCUIT FOR OPEN
	1 Disconnect GEM C320.
	2 Measure the resistance between the GEM C320 pin 15, circuit 31S-GJ7 (BK/BU), harness side and ground while pressing the horn switch.
	Is the resistance less than 5 ohms? Yes INSTALL a new GEM. REFER to: Generic Electronic Module (GEM) (419-10 Multifunction Electronic Modules, Removal and Installation). TEST the system for normal operation. No GO to A7.
A7: CHECK THE HORN SWITCH GROUND CIRCUIT
	1 Disconnect Clockspring C763 - Vehicles Without Stability Assist.
	2 Disconnect Clockspring C353 - Vehicles With Stability Assist.
	3 Measure the resistance between the clockspring C763 pin 7, circuit 31-GJ9 (BK) (vehicles without stability assist) or C353 pin 14, circuit 31-GJ9 (BK) (vehicles with stability assist), harness side and ground.
	Is the resistance less than 5 ohms? Yes GO to A8. No REPAIR circuit 31-GJ9 (BK). TEST the system for normal operation.
A8: CHECK CIRCUIT 31S-GJ7 (BK/BU) FOR OPEN CIRCUIT
	1 Measure the resistance between the clockspring C763 pin 6, circuit 31S-GJ7 (BK/BU) (vehicles without stability assist) or C353 pin 13, circuit 31S-GJ7 (BK/BU) (vehicles with stability assist), harness side and the GEM C320 pin 15, circuit 31S-GJ7 (BK/BU), harness side.
	Is the resistance less than 5 ohms? Yes GO to A9. No REPAIR the circuit. TEST the system for normal operation.
A9: CHECK THE CLOCKSPRING CIRCUIT FOR OPEN CIRCUIT
WARNING:To deactivate the driver air bag, refer to the procedure in section 501-20B for the correct air bag deactivation procedure. Failure to follow this instruction, may result in personal injury.
	1 Remove the driver air bag module. REFER to: Driver Air Bag Module (501-20B Supplemental Restraint System, Removal and Installation).
	2 Measure the resistance between the driver air bag connector, clockspring side and the clockspring C763 pin 6, circuit 31S-GJ7 (BK/BU) (vehicles without stability assist) or C353 pin 13, circuit 31S-GJ7 (BK/BU) (vehicles with stability assist) component side.
	Is the resistance less than 5 ohms? Yes GO to A10. No INSTALL a new clockspring. REFER to: Clockspring (501-20B Supplemental Restraint System, Removal and Installation). TEST the system for normal operation.
A10: CHECK THE CLOCKSPRING CIRCUIT FOR OPEN CIRCUIT
	1 Measure the resistance between the driver air bag connector, clockspring side and clockspring C763 pin 7, circuit 31-GJ9 (BK) (vehicles without stability assist) or C353 pin 14, circuit 31-GJ9 (BK) (vehicles with stability assist) component side.
	Is the resistance less than 5 ohms? Yes GO to A11. No INSTALL a new clockspring. REFER to: Clockspring (501-20B Supplemental Restraint System, Removal and Installation). TEST the system for normal operation.
A11: CHECK THE HORN SWITCH CIRCUIT FOR OPEN CIRCUIT
	1 Measure the resistance between the clockspring pin 6 and pin 7 (vehicles without stability assist) or pin 13 and pin 14 (vehicles with stability assist) component side while pressing the horn switch.
	Is the resistance less than 5 ohms? Yes INSTALL a new GEM. REFER to: Generic Electronic Module (GEM) (419-10 Multifunction Electronic Modules, Removal and Installation). TEST the system for normal operation. No INSTALL a driver air bag module. REFER to: Driver Air Bag Module (501-20B Supplemental Restraint System, Removal and Installation). TEST the system for normal operation.

PINPOINT TEST B : THE HORN IS ALWAYS ON
TEST CONDITIONS	DETAILS/RESULTS/ACTIONS
B1: CHECK THE HORN SWITCH CIRCUIT FOR SHORT TO GROUND
	1 Disconnect GEM C320.
	Does the horn stop sounding with C320 disconnected? Yes GO to B2. No INSTALL a new GEM. REFER to: Generic Electronic Module (GEM) (419-10 Multifunction Electronic Modules, Removal and Installation). TEST the system for normal operation.
B2: CHECK CIRCUIT 31S-GJ7 (BK/BU) FOR SHORT TO GROUND
	1 Disconnect Clockspring C763 - Vehicles Without Stability Assist.
	2 Disconnect Clockspring C353 - Vehicles With Stability Assist.
	3 Measure the resistance between the GEM C320 pin 15, circuit 31S-GJ7 (BK/BU), harness side and ground.
	Is the resistance greater than 10,000 ohms? Yes GO to B3. No REPAIR the circuit. TEST the system for normal operation.
B3: CHECK THE CLOCKSPRING FOR SHORT TO GROUND
WARNING:To deactivate the driver air bag, refer to the procedure in section 501-20B for the correct air bag deactivation procedure. Failure to follow this instruction, may result in personal injury.
	1 Remove the driver air bag module. REFER to: Driver Air Bag Module (501-20B Supplemental Restraint System, Removal and Installation).
	2 Measure the resistance between the clockspring C763 pin 6, circuit 31S-GJ7 (BK/BU) (vehicles without stability assist) or C353 pin 13, circuit 31S-GJ7 (BK/BU) (vehicles with stability assist) component side and ground.
	Is the resistance greater than 10,000 ohms? Yes INSTALL a new driver air bag module. REFER to: Driver Air Bag Module (501-20B Supplemental Restraint System, Removal and Installation). TEST the system for normal operation. No INSTALL a new clockspring. REFER to: Clockspring (501-20B Supplemental Restraint System, Removal and Installation). TEST the system for normal operation.