Horns Malfunction
Horns Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The right steering wheel control switch monitors the horn switch signal circuit, when the horn pad is pressed, the right steering wheel control switch detects the drop in the horn switch signal circuit and sends a serial data message to the underhood fuse block which commands the horn to sound.
Diagnostic Aids
If diagnosing a Horn- Poor Tone condition, inspect the following:
* Debris or water in the horn assembly.
* Proper horn mounting hardware torque. Refer to Fastener Tightening Specifications (Specifications) .
* Debris in the joint where the horns attach to the vehicle.
Reference Information
Schematic Reference
Horn Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Horns System Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool Horn Relay Status parameter while pressing and releasing the horn pad, the parameter should change from On to Off.
• If the parameter does not change, refer to Horn Switch Circuit Test.
2. Ignition ON, command the horn ON and OFF with a scan tool. The horn should sound when changing between the commanded states.
• If the horn does not sound, refer to Horn Circuit Test.
• If the sound emitted is not clear and even, refer to Horn - Poor Tone.
Circuit/System Testing
Horn Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the horn switch.
2. Test for less than 1 ohm between the ground circuit terminal and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Horn Relay Status parameter is Off.
• If not the specified parameter, test the signal circuit terminal for a short to ground. If the circuit tests normal, replace the right steering wheel control switch.
4. If all circuits test normal, replace the horn switch.
Horn Circuit Test
1. Ignition OFF, disconnect the harness connector at the horn.
2. Ignition OFF, test for less than 1 ohm between the ground circuit terminal 2 and ground.
• If greater than the specified range, test the ground circuit for and open/high resistance.
3. Connect a test lamp between the control circuit terminal 1 and ground.
4. Press and release the horn switch. The test lamp should turn ON and OFF when changing between the commanded states.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.
• If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the underhood fuse block.
5. If all circuit test normal, test or replace the horn.
Horn - Poor Tone
1. Ignition OFF, disconnect the harness connector at the horn.
2. Test for less than 1 ohm between the horn ground circuit terminal 2 and ground.
• If greater than the specified range, test the ground circuit for a high resistance.
3. Disconnect the X1 harness connector at the underhood fuse block.
4. Test for less than 1 ohm between the control circuit terminal 32 at the underhood fuse block and the control circuit terminal 1 at the horn.
• If greater than the specified range, test the control circuit for a high resistance.
5. If all circuits test normal, test or replace the horn.
Component Testing
Horn
1. Ignition OFF, disconnect the harness connector at the horn.
2. Install a 15A fused jumper wire between the control terminal 1 and 12 volts. Install a jumper wire between the ground terminal 2 and ground. Verify the horn emits a clear and even tone.
• If the sound emitted is not clear and even, replace the horn.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Steering Wheel Horn Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for underhood fuse block replacement, setup, and programming