Horns Schematic Icons
Horns Schematic Icons Icon Icon Definition CAUTION: When performing service on or near the SIR components or the SIR wiring, the SIR system must be disabled. Refer to SIR Disabling and Enabling Zone 3 in SIR article. Failure to observe the correct procedure could cause deployment of the SIR components, personal injury or unnecessary SIR system repairs
Scheme 1
Scheme 2
| Callout | Component Name |
|---|---|
| 1 | Hood Ajar Switch (AP3) |
| 2 | Inflatable Restraint Front End Sensor - Left |
| 3 | Horn - Left |
| 4 | Cooling Fan - Left |
| 5 | Cooling Fan - Right |
| 6 | Ambient Air Temperature Sensor (UH8 or UH9) |
| 7 | Horn - Right |
| 8 | Inflatable Restraint Front End Sensor - Right |
| 9 | Hood Ajar Switch Connector (AP3) |
Scheme 3
| Callout | Component Name |
|---|---|
| 1 | Horn Switch Connector |
| 2 | Cruise Control Lever Connector (K34) |
| 3 | Steering Wheel Control Switch Assembly - Right (UK3) |
| 4 | Cruise Control Lever (K34) |
| 5 | S293 (UK3) |
| 6 | S297 (UK3) |
| 7 | Steering Wheel Ground |
| 8 | C279 Inflatable Restraint Steering Wheel Module Coil to Steering Wheel Harness |
| 9 | S295 (UK3) |
| 10 | Steering Wheel Control Switch Assembly - Left (UK3) |
Scheme 4
| Connector Part Information OEM: 12052644 Service: See Catalog Description: 2-Way F Metri-Pack 150 Series Sealed (L-GY) |
|---|
| Terminal Part Information Terminal: Not Serviced in Kit Core/Insulation Crimp: N/A Release Tool/Test Probe: N/A |
Horns Connector End Views
| Pin | Wire Color | Circuit No. | Function |
|---|---|---|---|
| A | BK | 1350 | Ground |
| B | D-GN | 29 | Horn Control |
Horn - Left
Horn - Right
| Connector Part Information OEM: 12052644 Service: See Catalog Description: 2-Way F Metri-Pack 150 Series Sealed (L-GY) |
|---|
| Terminal Part Information Terminal: Not Serviced in Kit Core/Insulation Crimp: N/A Release Tool/Test Probe: N/A |
Horns Connector End Views
| Pin | Wire Color | Circuit No. | Function |
|---|---|---|---|
| A | BK | 1250 | Ground |
| B | D-GN | 29 | Horn Control |
Horn - Right
Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2: Listen for an audible click when the horn relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
- 3: Tests for voltage at the coil side of the horn relay. The horn fuse supplies power to the coil side of the horn relay.
- 4: Verifies that the BCM is providing ground to the horn relay.
- 5: Tests if ground is constantly being applied to the horn relay.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Horns Schematics Connector End View Reference: Horns Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, command the horn relay ON and OFF. Does the horn relay turn ON and OFF with each command? | Go to Diagnostic Aids | Go to Step 3 |
| 3 | Turn OFF the ignition. Disconnect the horn relay. Turn ON the ignition, with the engine OFF. Probe the battery positive voltage circuit of the horn relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 4 | Go to Step 10 |
| 4 | Connect a test lamp between the control circuit of the horn relay and the battery positive voltage circuit of the horn relay. With a scan tool, command the horn relay ON and OFF. Does the test lamp turn ON and OFF with each command? | Go to Step 8 | Go to Step 5 |
| 5 | Does the test lamp remain illuminated with each command? | Go to Step 7 | Go to Step 6 |
| 6 | Test the control circuit of the horn relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 9 |
| 7 | Test the control circuit of the horn relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 9 |
| 8 | Inspect for poor connections at the horn relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 11 |
| 9 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 12 |
| 10 | Repair the battery positive voltage circuit of the horn relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 13 | |
| 11 | Replace the horn relay. Did you complete the replacement? | Go to Step 13 | |
| 12 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming. Did you complete the replacement? | Go to Step 13 | |
| 13 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset? | Go to Step 2 | System OK |
DTC B2750
Symptoms - Horns
| IMPORTANT | The following steps must be completed before using the symptom tables |
- On vehicles equipped with content theft deterrent (UA6), perform «Diagnostic System Check - Vehicle»(ref-241670-S16610990062006081100000) in Vehicle DTC Information, before using the symptom tables in order to verify that there are no DTCs set.
- Review the system operation in order to familiarize yourself with the system functions. Refer to «Horns System Description and Operation»(ref-241673-S16097291542006081100000) .
The numbers below refer to the step numbers on the diagnostic table.
- 8: Tests if ground is constantly being applied to the horn relay.
- 10: The horn relay control circuit includes the horn slip ring and the horn switch. The horn switch is part of the inflatable restraint steering wheel module. The horn slip ring and the horn switch must be tested for a short to ground.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Is the vehicle equipped with content theft deterrent (UA6)? | Go to Step 2 | Go to Step 3 |
| 2 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 4 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 3 | Did you review the horns operation and perform the necessary inspections? | Go to Step 4 | Go to Symptoms - Horns |
| 4 | Depress and release the horn switch. Is the horn on at all times? | Go to Step 5 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems |
| 5 | Is the vehicle equipped with theft deterrent (UA6)? | Go to Step 6 | Go to Step 7 |
| 6 | Disconnect the body control module (BCM). Is the horn on at all times? | Go to Step 7 | Go to Step 11 |
| 7 | Disconnect the horn relay. Is the horn on at all times? | Go to Step 12 | Go to Step 8 |
| 8 | Connect a test lamp between the battery positive voltage circuit of the horn relay coil and the horn relay control circuit. Does the test lamp illuminate? | Go to Step 10 | Go to Step 9 |
| 9 | Inspect for poor connections at the horn relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 14 |
| 10 | IMPORTANT: The horn switch is part of the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement in SIR. To disable the SIR system refer to SIR Disabling and Enabling Zone 3 in SIR. Repair the short to ground in the horn relay control circuit. The horn relay control circuit includes the horn slip ring and the horn switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 15 | |
| 11 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 13 |
| 12 | Repair the short to voltage in the horn control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 15 | |
| 13 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming. Did you complete the replacement? | Go to Step 15 | |
| 14 | Replace the horn relay. Did you complete the replacement? | Go to Step 15 | |
| 15 | Operate the horn. Does the horn operate properly? | System OK | Go to Step 1 |
| IMPORTANT |
|---|
| The horn switch is part of the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement in SIR. |
Horns Always On
The numbers below refer to the step numbers on the diagnostic table.
- 5: This step tests for voltage at the battery positive voltage terminal of the horn relay coil.
- 7: This step tests for voltage at the battery positive voltage terminal of the horn relay switch. The HORN fuse supplies power to the battery positive voltage terminal of the horn relay switch.
- 12: The horn needs maximum current flow to operate properly. A high resistance, greater than 0.5 ohm, in the horn control circuit or the horn ground circuit could cause operating problems with the horn. Inspect the circuits for faults that would restrict current flow.
- 14: The horn relay control circuit includes the horn slip ring and the horn switch. The horn switch is part of the inflatable restraint steering wheel module. The horn slip ring and the horn switch must be tested for a high resistance, an open or a short to voltage when testing the relay control circuit.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Is the vehicle equipped with content theft deterrent (UA6)? | Go to Step 2 | Go to Step 3 |
| 2 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 4 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 3 | Did you review the horns operation and perform the necessary inspections? | Go to Step 4 | Go to Symptoms - Horns |
| 4 | Depress the horn switch. Does the horn operate? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 5 |
| 5 | Disconnect the horn relay. Connect a test lamp between the battery positive voltage circuit of the horn relay coil and a good ground. Does the test lamp illuminate? | Go to Step 6 | Go to Step 13 |
| 6 | Connect a test lamp between the battery positive voltage circuit of the horn relay coil and the horn relay control circuit. Depress and hold the horn switch. Does the test lamp illuminate? | Go to Step 7 | Go to Step 14 |
| 7 | Connect a test lamp between the battery positive voltage circuit of the horn relay switch and a good ground. Does the test lamp illuminate? | Go to Step 8 | Go to Step 15 |
| 8 | Momentarily connect a 15-amp fused jumper wire between the battery positive voltage circuit of the horn relay switch and the horn control circuit. Does the horn operate? | Go to Step 11 | Go to Step 9 |
| 9 | Reconnect the horn relay. Disconnect the horn connector. Connect a test lamp between the horn control circuit and a good ground. Depress and hold the horn switch. Does the test lamp illuminate? | Go to Step 10 | Go to Step 16 |
| 10 | Connect a test lamp between the horn control circuit and the horn ground circuit. Depress and hold the horn switch. Does the test lamp illuminate? | Go to Step 12 | Go to Step 17 |
| 11 | Inspect for poor connections at the horn relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 19 | Go to Step 18 |
| 12 | Repair the high resistance in the horn control circuit or the horn ground circuit. A resistance as low as 0.5 ohm could cause operating problems with the horns. Also, though unlikely, it is possible that both horns are defective. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 19 | |
| 13 | Repair the open or high resistance in the battery positive voltage circuit of the horn relay coil. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 19 | |
| 14 | IMPORTANT: The horn switch is part of the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement in SIR. Disable the SIR system. Refer to SIR Disabling and Enabling Zone 3 in SIR. Repair the open or short to voltage in the horn relay control circuit. The horn relay control circuit includes the horn slip ring and the horn switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 19 | |
| 15 | Repair the open or high resistance in the battery positive voltage circuit of the horn relay switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 19 | |
| 16 | Repair the open or high resistance in the horn control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 19 | |
| 17 | Repair the open or high resistance in the horn ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 19 | |
| 18 | Replace the horn relay. Did you complete the replacement? | Go to Step 19 | |
| 19 | Operate the horn. Does the horn operate properly? | System OK | Go to Step 1 |
| IMPORTANT |
|---|
| The horn switch is part of the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement in SIR. |
Horns Inoperative
Horns - Poor Tone
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Is the vehicle equipped with content theft deterrent (UA6)? | Go to Step 2 | Go to Step 3 |
| 2 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 4 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 3 | Did review the horns operation and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Horns |
| 4 | Depress the horn switch. Does the horn have a harsh tone or buzzing? | Go to Step 5 | Go to Symptoms - Horns |
| 5 | Test the horn mounting hardware for adequate torque. The hardware should be tightened to 10 N.m (7 lb ft). Inspect the horn for debris in the joint where the horn attaches to the vehicle. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 |
| 6 | Perform the following for each of the horns: Disconnect the horn connector. Connect a 15-amp fused jumper wire between the positive battery terminal and the control terminal of the horn. Connect another jumper wire between the negative battery terminal and the ground terminal of the horn. Does the horn have a harsh tone or buzzing? | Go to Step 8 | Go to Step 7 |
| 7 | Repair the high resistance in the horn control circuit or the horn ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 9 | |
| 8 | Replace the horn. Refer to Horn Replacement . Did you complete the replacement? | Go to Step 9 | |
| 9 | Operate the horn. Does the horn operate properly? | System OK | Go to Step 1 |
Horns - Poor Tone
System Description
The horn system consists of the following components
- HORN fuse
- Horn relay
- Horn switch (Part of the multifunction turn signal lever)
- Horn assembly
- Body Control Module (BCM)
System Operation
The body control module (BCM) commands the horns on. The BCM commands the horns on under any of the following conditions
- When the horn switch is depressed.
- When the panic button is depressed on the remote control door lock transmitter. For further information refer to «Keyless Entry System Description and Operation»(ref-241691-S22882930082006081100000) in Keyless Entry.
- When the keyless entry system is used to lock the vehicle, a horn chirp may sound to notify the driver that the vehicle has been locked.
Circuit Operation
Battery positive voltage is applied at all times to the horn relay coil and the horn relay switch. Pressing the horn switch applies ground to the horn switch signal circuit. The BCM applies ground to the horn relay control circuit as described above. When the horn relay control circuit is grounded, the horn relay is energized and battery positive voltage is applied to the horns through the horn control circuit. The horns sound as long as ground is applied to the horn relay control circuit.