Ford Workshop Service and Repair Manuals

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

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 central junction box(CJB) and is supplied with a permanent voltage from the battery junction box (BJB).

The steering wheel switch shares the steering wheel clock-spring with the air-bag circuit although each of these systems work completely independent of each other.

Inspection and Verification

Visual Inspection Chart

Symptom Chart

Symptom Chart

Pinpoint Tests

NOTE:Use a digital multimeter for all electrical measurements.

PINPOINT TEST A : THE HORN(S) SOUND CONTINUOUSLY
TEST CONDITIONS	DETAILS/RESULTS/ACTIONS
A1: CHECK CIRCUIT 29S-GJ1 OG/BU FOR SHORT TO BATTERY POSITIVE
	1 Disconnect Horn Relay K33.
	Does the horn stop when the relay is disconnected? Yes GO to A2. No REPAIR circuit 29S-GJ1 (OG/BU), for short to battery positive. TEST the system for normal operation.
A2: CHECK CIRCUIT 91S-GJ7 (BK/BU) FOR SHORT TO GROUND
	1 Measure the resistance between the horn relay connector pin 2 91S-GJ7 (BK/BU), and ground.
	Is the resistance greater than 10,000 ohms (open circuit)? Yes INSTALL a new horn relay. TEST the system for normal operation. No Vehicles with stabilty assist, GO to A3. Vehicles without stabilty assist, GO to A4.
A3: CHECK STEERING WHEEL HORN SWITCH
	1 Remove the air-bag. REFER to: Driver Air Bag Module (501-20B Supplemental Restraint System, Removal and Installation).
	2 Remove the steering column lower shroud.
	3 Disconnect Clockspring C896.
	4 Measure the resistance between the clockspring C896 component side, pin 6 and pin 7.
	Is the resistance greater than 10,000 ohms (open circuit)? Yes Install a new relay. TEST the system for normal operation. No GO to A5.
A4: CHECK STEERING WHEEL HORN SWITCH
	1 Remove the air-bag. REFER to: Driver Air Bag Module (501-20B Supplemental Restraint System, Removal and Installation).
	2 Remove the steering column lower shroud.
	3 Disconnect Clockspring C898.
	4 Measure the resistance between clockspring C898 component side, pin 13 and pin 14.
	Is the resistance greater than 10,000 ohms (open circuit)? Yes Install a new relay. TEST the system for normal operation. No GO to A5.
A5: CHECK STEERING WHEEL HORN SWITCH
	1 Disconnect Horn Switch C920.
	2 Using a digital multimeter, measure the resistance between the Horn switch C920, pin 1 and pin 2.
	Is the resistance greater than 10,000 ohms (open circuit)? Yes INSTALL a new clockspring. REFER to: Clockspring (501-20B Supplemental Restraint System, Removal and Installation). TEST the system for normal operation. No INSTALL a new Horn switch(es). TEST the system for normal operation.

PINPOINT TEST B : THE HORN DOES NOT SOUND
TEST CONDITIONS	DETAILS/RESULTS/ACTIONS
B1: CHECK FUSE 7 (40A)
	1 CHECK Fuse 7 (40A) Central Junction Box.
	Is the Audio Unit operating correctly? Yes GO to B2. No INSTALL a new fuse 7. TEST the system for normal operation.
B2: CHECK FUSE 34 (20A)
	1 CHECK Fuse 33 (20A) Central Junction Box.
	Is the fuse OK? Yes GO to B3. No INSTALL a new fuse 33. TEST the system for normal operation.
B3: CHECK THE HORN RELAY
	1 Disconnect Horn Relay K33.
	2 Perform the relay component test.
	Is the relay OK? Yes GO to B4. No INSTALL a new Horn relay. TEST the system for normal operation.
B4: CHECK POWER TO THE CJB
	1 Measure the voltage between the Horn relay C1023 pin 1, harness side and ground, and the Horn relay C1023 pin 3, harness side and ground.
	Are the voltages greater than 10 volts? Yes Vehicles with stabilty assist, GO to B5. Vehicles without stabilty assist, GO to B8. No REPAIR circuit 30-DA1 (RD). TEST the system for normal operation.
B5: CHECK POWER TO HORN SWITCH
	1 Connect Horn Relay K33.
	2 Remove the air-bag. REFER to: Driver Air Bag Module (501-20B Supplemental Restraint System, Removal and Installation).
	3 Disconnect Clockspring C896.
	4 Remove the steering column lower shroud.
	5 Measure the voltage between the clockspring C896 pin 6, circuit 91S-GJ7 (BK/BU), harness side and ground.
	Is the voltage greater than 10 volts? Yes GO to B6. No REPAIR circuit 91S-GJ7 (BK/BU), TEST the system for normal operation.
B6: CHECK HORN SWITCH GROUND CIRCUIT
	1 Measure the resistance between the clockspring C896 pin 7, circuit 91-PG30 (BK/WH), harness side and ground.
	Is the resistance less than 1 ohm? Yes GO to B7. No REPAIR circuit 91-PG30 (BK/WH), TEST the system for normal operation.
B7: CHECK OPERATION OF CLOCKSPRING
	1 Measure the resistance between the clockspring component side C896 pin 6 and pin 7. Take note of the reading with the switch pressed as well as with the switch released.
	Is the resistance greater than 10,000 ohms (open circuit) with the switch released and less than 1 ohm with the switch pressed? Yes GO to B12. No GO to B11.
B8: CHECK POWER TO HORN SWITCH
	1 Connect Horn Relay K33.
	WARNING:For correct deactivation procedure of air-bag, refer to procedure in Section 501-20B. 2 Remove the air-bag. REFER to: Driver Air Bag Module (501-20B Supplemental Restraint System, Removal and Installation).
	3 Disconnect Clockspring C898.
	4 Remove the steering column lower shroud.
	5 Measure the voltage between the clockspring C898 pin 13, circuit 91S-GJ7 (BK/BU), harness side and ground.
	Is the voltage greater than 10 volts? Yes GO to B9. No REPAIR circuit 91S-GJ7 (BK/BU), TEST the system for normal operation.
B9: CHECK HORN SWITCH GROUND CIRCUIT
	1 Measure the resistance between the clockspring C898 pin 14, circuit 91-PG30 (BK/WH), harness side and ground.
	Is the resistance less than 1 ohm? Yes GO to B10. No REPAIR circuit 91-PG30 (BK/WH), TEST the system for normal operation.
B10: CHECK OPERATION OF AIR-BAG SLIDING CONTACT
	1 Measure the resistance between the clockspring component side C898 pin 13 and pin 14. Take note of the reading with the switch pressed as well as with the switch released.
	Is the resistance greater than 10,000 ohms (open circuit) with the switch released and less than 1 ohm with the switch pressed? Yes For vehciles with single horn, GO to B12. For vehciles with dual horns, GO to B14. No GO to B11.
B11: CHECK HORN SWITCH
	1 Disconnect Horn Switch C920.
	2 Measure the resistance between the horn switch C920 pin 1 and pin 2. Take note of the reading with the switch pressed as well as with the switch released.
	Is the resistance greater than 10,000 ohms (open circuit) with the switch released and less than 1 ohm with the switch pressed? Yes Install a new air-bag sliding contact. TEST the system for normal operation. No INSTALL new horn switch(es). TEST the system for normal operation.
B12: CHECK POWER TO THE HORN
	1 Connect Clockspring C896 or C898.
	2 Connect Horn Switch C920.
	3 Disconnect Horn C77.
	4 Measure the voltage at horn C77 pin 1, circuit 29S-GJ1 (OG/BU), harness side and ground, whilst depressing the horn switch.
	Is the voltage greater than 10 volts? Yes GO to B13. No REPAIR circuit 29S-GJ1 (OG/WH). TEST the system for normal operation.
B13: CHECK GROUND CIRCUIT TO HORN
	1 Measure the resistance between Horn C77 pin 2 circuit 31-GJ1 (BK), harness side and ground.
	Is the resistance less than 1 ohm? Yes INSTALL new horn. TEST the system for normal operation. No REPAIR circuit 31-GJ1 (BK). TEST the system for normal operation.
B14: CHECK POWER TO THE HORN(S)
	1 Connect Clockspring C896 or C898.
	2 Connect Horn Switch C920.
	3 Disconnect Horn C982 or C981.
	4 Measure the voltage at Horn(s) C982 pin 1, circuit 29S-GJ6 (OG/YE), harness side and ground; and C981 pin 1, circuit 29S-GJ10 (OG/GN), harness side and ground, whilst depressing the horn switch.
	Are the voltages greater than 10 volts? Yes GO to B15. No REPAIR circuit 29S-GJ6 (OG/YE) or 29S-GJ10 (OG/GN) as necessary. TEST the system for normal operation.
B15: CHECK GROUND CIRCUIT TO HORN(S)
	1 Measure the resistance between the horn(s) C982 pin 2, circuit 31-GJ6 (BK), harness side and ground; and C981 pin 2, circuit 31-GJ10 (BK), harness side and ground.
	Are the resistances less than 1 ohm? Yes INSTALL new Horn(s) as necessary. TEST the system for normal operation. No REPAIR circuit 31-GJ6 (BK) or circuit 31-GJ10 (BK) as necessary. TEST the system for normal operation.

Component Test