Read Horn.pdf text version

413-06-1

Horn

413-06-1

DIAGNOSIS AND TESTING

Horn

Refer to Wiring Diagrams Cell 44 for schematic and connector information.

Special Tool(s) 73III Automotive Meter 105-R0057 or equivalent

4.

If the cause is not visually evident, connect the diagnostic tool to the data link connector (DLC) and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle: · · · check that the program card is correctly installed. check the connections to the vehicle. check the ignition switch position.

5.

Worldwide Diagnostic System (WDS) Vehicle Communication Module (VCM) with appropriate adapters, or equivalent diagnostic tool

If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool operating manual. Carry out the diagnostic tool data link test. If the diagnostic tool responds with: · CAN circuits fault; all electronic control units no response/not equipped, refer to Section 418-00. No response/not equipped for the smart junction box (SJB), refer to Section 419-10. System passed, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs, and carry out self-test diagnostics for the smart junction box (SJB) and the instrument cluster.

6.

·

Principles of Operation

The horn switch is incorporated within the steering wheel. When the switch is closed, ground is supplied through the clockspring from the vehicle harness. The horn relay is than energized, supplying voltage to the horn enabling the horn to sound. The horn relay is located in the bussed electrical center (BEC). ·

7.

Inspection and Verification

1. 2. Verify the customer concern. Visually inspect for obvious signs of mechanical or electrical damage. 8.

If the DTCs retrieved are related to the concern, go to the Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Index. If no DTCs related to the concern are retrieved, GO to Symptom Chart.

Visual Inspection Chart Mechanical · Horns · Horn switch (part of the steering wheel) · Clockspring Electrical · Bussed electrical center (BEC) fuse 46 (25A) · Circuitry · Horn relay · Horn switch (part of the steering wheel)

3.

If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

Copyright © 2004, Ford Motor Company

Last updated: 7/21/2005

2005 Mustang, 12/2004

413-06-2

Horn

413-06-2

DIAGNOSIS AND TESTING (Continued)

Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Index DTC B1342 Description ECU is Faulted Source SJB Action DOCUMENT and CLEAR the DTCs. REPEAT the self-test. If DTC B1342 is retrieved again, INSTALL a new SJB. REFER to Section 419-10. GO to Pinpoint Test A. REFER to Section 419-10.

B1897 All Other DTCs

Horn Switch Circuit Failure --

SJB SJB

Symptom Chart

Symptom Chart Condition · The horn is inoperative · · · · · · · The horn is always on · · · · · · · Possible Sources Circuitry Horn relay Horn switch (part of the steering wheel) Horns Clockspring Bussed electrical center (BEC) Smart junction box (SJB) Circuitry Horn switch (part of the steering wheel) Clockspring Horn relay Bussed electrical center (BEC) Smart junction box (SJB) Action · GO to Pinpoint Test A.

· GO to Pinpoint Test B.

Connector Circuit Reference

Horn C131

Pin Number(s) 1 2

Circuit Designation/Description 1205 (BK) ground 6 (YE/LG) horn relay switched power output

Normal Condition/Measurement Less than 5 ohms between the horn and ground. 0 volts with the horn switch released. Greater than 10 volts with the horn switch pressed. Less than 5 ohms between the horn and the bussed electrical center (BEC). Greater than 10,000 ohms between the horn and ground. 2005 Mustang, 12/2004

413-06-3

Horn

413-06-3

DIAGNOSIS AND TESTING (Continued)

Horn Relay C1006

Pin Number(s) 30

Circuit Designation/Description Horn relay switched circuit

Normal Condition/Measurement 0 volts. Less than 5 ohms between the horn relay and the horn. Greater than 10,000 ohms between the horn relay and ground, with the horn disconnected. 0 volts, less than 5 ohms between the horn relay and ground when the horn button is pressed and greater than 10,000 ohms between the horn relay and ground when the horn button is released. Greater than 10 volts at all times. Greater than 10 volts at all times.

85

Horn relay switched coil

86 87

Horn relay coil voltage Horn relay switched voltage

Bussed Electrical Center (BEC) C1035a

Pin Number(s) A1

Circuit Designation/Description 1323 (OG/RD) horn relay control

Normal Condition/Measurement Less than 5 ohms between the BEC and the smart junction box (SJB). Greater than 10,000 ohms between the BEC and ground.

Bussed Electrical Center (BEC) C1035c

2005 Mustang, 12/2004

413-06-4

Horn

413-06-4

DIAGNOSIS AND TESTING (Continued)

Pin Number(s) D4 Circuit Designation/Description 6 (YE/LG) horn relay switched power output Normal Condition/Measurement Less than 5 ohms between the BEC and the horn.

Clockspring C2274

Pin Number(s) 7

Circuit Designation/Description 1 (DB) horn switch control

Normal Condition/Measurement Less than 5 ohms between the clockspring and the smart junction box (SJB). Greater than 10,000 between the clockspring and ground.

Smart Junction Box (SJB) C2280b

Pin Number(s) 39

Circuit Designation/Description 1 (DB) horn switch control

Normal Condition/Measurement Greater than 10,000 ohms to ground with the horn switch released. Less than 5 ohms to ground with the horn switch pressed.

Smart Junction Box (SJB) C2280c

Pin Number(s) 29

Circuit Designation/Description 1323 (OG/RD) horn relay control

Normal Condition/Measurement Greater than 10 volts at all times.

2005 Mustang, 12/2004

413-06-5

Horn

413-06-5

DIAGNOSIS AND TESTING (Continued)

Upper Clockspring Connector

Pin Number(s) 4

Circuit Designation/Description (GN) horn switch ground

Normal Condition/Measurement Less than 5 ohms between the upper clockspring pin 4 and the upper clockspring pin 5 with the horn switch pressed. Greater then 10,000 ohms between the upper clockspring pin 4 and the upper clockspring pin 5 with the horn switch released. Less than 5 ohms between the upper clockspring pin 5 and the upper clockspring pin 4 with the horn switch pressed. Greater then 10,000 ohms between the upper clockspring pin 5 and the upper clockspring pin 4 with the horn switch released.

5

(BK) horn switch signal circuit

Pinpoint Test A: The Horn Is Inoperative Normal Operation The horn relay control and switched voltage is supplied by the bussed electrical center (BEC) through circuit 2037 (RD). The smart junction box (SJB) receives the horn signal through circuit 1 (DB) from the horn switch (part of the steering wheel). When the horn switch is pressed, ground is supplied from the clockspring to the vehicle harness through circuit 1205 (BK). The SJB then activates the horn relay through circuit 1323 (OG/RD). Voltage is then sent to the horn through circuit 6 (YE/LG), enabling the horns to sound. Ground is provided to the horns through circuit 1205 (BK).

Possible Causes · circuit 1 (DB) open · circuit 6 (YE/LG) open · circuit 1205 (BK) open · circuit 1323 (OG/RD) open · horn relay · horn switch (part of the steering wheel) · horns · clockspring · BEC · SJB

PINPOINT TEST A: THE HORN IS INOPERATIVE

A1 Test Step TRIGGER THE SJB HORN CONTROL ACTIVE COMMAND · Connect the diagnostic tool. · Key in ON position. · Enter the following diagnostic mode on the diagnostic tool: Smart Junction Box (SJB) Active Commands. · Select the SJB active command for the horn. · Trigger the SJB horn active command on. · Does the horn sound? Result / Action to Take

Yes

GO to A10.

No

GO to A2.

(Continued)

2005 Mustang, 12/2004

413-06-6

Horn

PINPOINT TEST A: THE HORN IS INOPERATIVE (Continued)

413-06-6

DIAGNOSIS AND TESTING (Continued)

Test Step CHECK THE HORN RELAY FOR CORRECT OPERATION · Key in OFF position. · Disconnect: Horn Relay C1006. Carry out the horn relay component test. Refer to Wiring Diagrams Cell 149 for component testing. · Is the horn relay OK? CHECK THE SJB OUTPUT · Connect: Horn Relay C1006. · Disconnect: SJB C2280c. · Connect a fused (10A) jumper wire between the SJB C2280c-29, circuit 1323 (OG/RD), harness side and ground. Result / Action to Take

A2

Yes

GO to A3.

No

INSTALL a new horn relay. TEST the system for normal operation.

A3

Yes

REMOVE the jumper wire. GO to A11.

No

A4 · Does the horn sound? CHECK THE HORN RELAY CONTROL FOR AN OPEN · Disconnect: Horn Relay C1006. LEAVE the jumper wire connected. GO to A4.

(Continued)

2005 Mustang, 12/2004

413-06-7

Horn

PINPOINT TEST A: THE HORN IS INOPERATIVE (Continued)

413-06-7

DIAGNOSIS AND TESTING (Continued)

Test Step CHECK THE HORN RELAY CONTROL FOR AN OPEN (Continued) · Measure the resistance between the horn relay C1006-85, harness side and ground. Result / Action to Take

A4

Yes

REMOVE the jumper wire. GO to A6.

No

A5 · Is the resistance less than 5 ohms? CHECK CIRCUIT 1323 (OG/RD) FOR AN OPEN · Disconnect: BEC C1035a. · Measure the resistance between the SJB C2280c-29, circuit 1323 (OG/RD), harness side and the BEC C1035a-A1, circuit 1323 (OG/RD), harness side. REMOVE the jumper wire. GO to A5.

Yes

INSTALL a new BEC. TEST the system for normal operation.

No

A6 · Is the resistance less than 5 ohms? CHECK THE VOLTAGE SUPPLY TO THE HORN RELAY · Disconnect: Horn Relay C1006. REPAIR the circuit. TEST the system for normal operation.

(Continued)

2005 Mustang, 12/2004

413-06-8

Horn

PINPOINT TEST A: THE HORN IS INOPERATIVE (Continued)

413-06-8

DIAGNOSIS AND TESTING (Continued)

Test Step CHECK THE VOLTAGE SUPPLY TO THE HORN RELAY (Continued) · Measure the voltage between the horn relay C1006-86, harness side and ground; and between the horn relay C1006-87, harness side and ground. Result / Action to Take

A6

Yes

GO to A7.

No

A7 · Are the voltages greater than 10 volts? CHECK CIRCUIT 6 (YE/LG) FOR AN OPEN · Disconnect: BEC C1035c. · Disconnect: Horn C131. · Measure the resistance between the horn C131-2, circuit 6 (YE/LG), harness side and the BEC C1035c-D4, circuit 6 (YE/LG), harness side. INSTALL a new new BEC. TEST the system for normal operation.

Yes

GO to A8.

No

· Is the resistance less than 5 ohms? REPAIR the circuit. TEST the system for normal operation.

(Continued)

2005 Mustang, 12/2004

413-06-9

Horn

PINPOINT TEST A: THE HORN IS INOPERATIVE (Continued)

413-06-9

DIAGNOSIS AND TESTING (Continued)

Test Step CHECK CIRCUIT 1205 (BK) FOR AN OPEN · Measure the resistance between the horn C131-1, circuit 1205 (BK), harness side and ground. Result / Action to Take

A8

Yes

GO to A9.

No

A9 · Is the resistance less than 5 ohms? CHECK THE BEC FOR AN INTERNAL OPEN · Connect: BEC C1035c. · Connect a fused (5A) jumper wire between the horn relay C1006-30, harness side and the horn relay C1006-87, harness side. REPAIR the circuit. TEST the system for normal operation.

(Continued)

2005 Mustang, 12/2004

413-06-10

Horn

PINPOINT TEST A: THE HORN IS INOPERATIVE (Continued)

413-06-10

DIAGNOSIS AND TESTING (Continued)

Test Step CHECK THE BEC FOR AN INTERNAL OPEN (Continued) · Measure the voltage between the horn C131-2, circuit 6 (YE/LG), harness side and ground. Result / Action to Take

A9

Yes

INSTALL a new horn. REFER to Horn in this section. TEST the system for normal operation.

No

A10 · Is the voltage greater than 10 volts? CHECK THE HORN SIGNAL TO THE SJB · Key in OFF position. · Disconnect: SJB C2280b. · Measure the resistance between the SJB C2280b-39, circuit 1 (DB), harness side and ground, while pressing and releasing the horn switch. INSTALL a new BEC. TEST the system for normal operation.

Yes

· Is the resistance less than 5 ohms with the horn switch pressed, and greater than 10,000 ohms with the horn switch released? CHECK FOR CORRECT SJB OPERATION · Disconnect all the SJB connectors. · Check for: · corrosion · pushed-out pins · Connect all the SJB connectors and make sure they seat correctly. · Operate the system and verify the concern is still present. · Is the concern still present? CHECK CIRCUIT 1 (DB) FOR AN OPEN · Depower the supplemental restraint system (SRS). Refer to Section 501-20B. · Disconnect: Clockspring C2274. GO to A11.

No

GO to A12.

A11

Yes

INSTALL a new SJB. REFER to Section 419-10. TEST the system for normal operation.

No

The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

A12

(Continued)

2005 Mustang, 12/2004

413-06-11

Horn

PINPOINT TEST A: THE HORN IS INOPERATIVE (Continued)

413-06-11

DIAGNOSIS AND TESTING (Continued)

Test Step CHECK CIRCUIT 1 (DB) FOR AN OPEN (Continued) · Measure the resistance between the SJB C2280b-39, circuit 1 (DB), harness side and the clockspring C2274-7, circuit 1 (DB), harness side. Result / Action to Take

A12

Yes

GO to A13.

No

· Is the resistance less than 5 ohms? CHECK THE CLOCKSPRING FOR AN OPEN · Remove the driver side air bag module. Refer to Section 501-20B. · Disconnect: Upper Clockspring Connector. · Measure the resistance between the upper clockspring connector pin 5, component side and the clockspring C2274-7, component side; and between the upper clockspring connector pin 4, component side and the clockspring C2274-6, component side. REPAIR the circuit. REPOWER the SRS. REFER to Section 501-20B. TEST the system for normal operation.

A13

Yes

GO to A14.

No

· Are the resistances less than 5 ohms? INSTALL a new clockspring. REFER to Section 501-20B. TEST the system for normal operation.

(Continued)

2005 Mustang, 12/2004

413-06-12

Horn

PINPOINT TEST A: THE HORN IS INOPERATIVE (Continued)

413-06-12

DIAGNOSIS AND TESTING (Continued)

Test Step CHECK THE HORN SWITCH FOR CORRECT OPERATION · Measure the resistance between the upper clockspring connector pin 5, circuit 1 (BK), harness side and the upper clockspring connector pin 4, circuit 1205 (GN), harness side, while pressing and releasing the horn switch. Result / Action to Take

A14

Yes

REPAIR circuit 1205 (BK) between the clockspring and ground. INSTALL the driver air bag module. REFER to Section 501-20B. TEST the system for normal operation.

No

· Is the resistance less than 5 ohms with the horn switch pressed, and greater than 10,000 ohms with the horn switch released? INSTALL a new steering wheel. REFER to Section 211-04. INSTALL the driver air bag module. REFER to Section 501-20B. TEST the system for normal operation.

Pinpoint Test B: The Horn Is Always On Normal Operation The horn relay control and switched voltage is supplied by the bussed electrical center (BEC) through circuit 2037 (RD). The smart junction box (SJB) receives the horn signal through circuit 1 (DB) from the horn switch (part of the steering wheel). When the horn switch is pressed, ground is supplied from the clockspring to the vehicle harness through circuit 1205 (BK). The SJB then activates the horn relay through circuit 1323 (OG/RD). Voltage is then sent to the horn through circuit 6 (YE/LG), enabling the horns to sound. Ground is provided to the horns through circuit 1205 (BK).

Possible Causes · circuit 1 (DB) short to ground · circuit 6 (YE/LG) short to voltage · circuit 1323 (OG/RD) short to ground · horn switch (part of the steering wheel) · clockspring · horn relay · BEC · SJB

PINPOINT TEST B: THE HORN IS ALWAYS ON

B1 Test Step RETRIEVE THE SMART JUNCTION BOX (SJB) DIAGNOSTIC TROUBLE CODES (DTCs) · Check the recorded results from the SJB self-test. · Is DTC B1897 retrieved? Result / Action to Take

Yes

GO to B2.

No

GO to B5 B2 CHECK THE HORN SWITCH FOR A SHORT TO GROUND · Remove the driver air bag module. Refer to Section 501-20B. · Disconnect: Upper Clockspring Connector.

(Continued)

2005 Mustang, 12/2004

413-06-13

Horn

PINPOINT TEST B: THE HORN IS ALWAYS ON (Continued)

413-06-13

DIAGNOSIS AND TESTING (Continued)

Test Step CHECK THE HORN SWITCH FOR A SHORT TO GROUND (Continued) · Measure the resistance between the upper clockspring connector pin 5, circuit 1 (BK), harness side and the upper clockspring connector pin 4, circuit 1205 (GN), harness side. Result / Action to Take

B2

Yes

GO to B3.

No

INSTALL a new steering wheel. REFER to Section 211-04. INSTALL the driver air bag module. REFER to Section 501-20B. CLEAR the DTCs. REPEAT the self-test.

B3

· Is the resistance greater than 10,000 ohms? CHECK THE CLOCKSPRING FOR A SHORT TO GROUND · Connect: Upper Clockspring Connector. · Disconnect: Clockspring C218b. · Measure the resistance between the clockspring C2274-7, component side and the clockspring C2274-6, component side.

Yes

GO to B4.

No

INSTALL a new clockspring. REFER to Section 501-20B. INSTALL the driver air bag module. REFER to Section 501-20B. CLEAR the DTCs. REPEAT the self-test.

B4

· Is the resistance greater than 10,000 ohms? CHECK CIRCUIT 1 (DB) FOR A SHORT TO GROUND · Disconnect: SJB C2280b. · Install the driver air bag module. Refer to Section 501-20B.

(Continued)

2005 Mustang, 12/2004

413-06-14

Horn

PINPOINT TEST B: THE HORN IS ALWAYS ON (Continued)

413-06-14

DIAGNOSIS AND TESTING (Continued)

Test Step CHECK CIRCUIT 1 (DB) FOR A SHORT TO GROUND (Continued) · Measure the resistance between the SJB C2280b-39, circuit 1 (DB), harness side and ground. Result / Action to Take

B4

Yes

GO to B9.

No

B5 · Is the resistance greater than 10,000 ohms? CHECK THE SJB FOR CORRECT OPERATION · Key in OFF position. · Disconnect: SJB C2280c. · Does the horn continue to sound? CHECK CIRCUIT 1323 (OG/RD) FOR A SHORT TO GROUND · Disconnect: BEC C1035a. · Does the horn continue to sound? REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

Yes

GO to B6.

No

GO to B9.

B6

Yes

GO to B7.

No

REPAIR the circuit. TEST the system for normal operation. B7 CHECK CIRCUIT 6 (YE/LG) FOR A SHORT TO VOLTAGE · Disconnect: BEC C1035. · Disconnect: Horn C131. · Measure the voltage between the horn C131-2, circuit 6 (YE/LG), harness side and ground.

Yes

REPAIR the circuit. TEST the system for normal operation.

No

B8 · Is any voltage present? CHECK THE HORN RELAY FOR CORRECT OPERATION · Disconnect: Horn Relay C1006. Carry out the horn relay component test. Refer to Wiring Diagrams Cell 149 for component testing. · Is the horn relay OK? GO to B8.

Yes

INSTALL a new BEC. TEST the system for normal operation.

No

INSTALL a new horn relay. TEST the system for normal operation.

(Continued)

2005 Mustang, 12/2004

413-06-15

Horn

PINPOINT TEST B: THE HORN IS ALWAYS ON (Continued)

413-06-15

DIAGNOSIS AND TESTING (Continued)

Test Step CHECK FOR CORRECT SJB OPERATION · Disconnect all the SJB connectors. · Check for: · corrosion · pushed-out pins · Connect all the SJB connectors and make sure they seat correctly. · Operate the system and verify the concern is still present. · Is the concern still present? Result / Action to Take

B9

Yes

INSTALL a new SJB. REFER to Section 419-10. TEST the system for normal operation.

No

The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

2005 Mustang, 12/2004

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