Horns Malfunction
Horns Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
Battery positive voltage is applied at all times to the horn relay coil and the horn relay switch. Pressing the horn switch applies ground through the switch contacts and the horn relay control circuit to the coil side of the relay, energizing the relay. Battery voltage is then applied through the switch side of the relay and the horn control circuit to the horns.
Diagnostic Aids
A short to ground in the horn relay control circuit or a short to voltage in the horn control circuit will cause the horn to sound continuously until the horn overheats and become inoperative.
Rotate the steering wheel while pressing the horn pad to identify intermittent and poor connections within the steering column.
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.
* Debris in direct contact with the horn
* Vehicle components vibrating while the horn is sounding
Reference Information
Schematic Reference
Horn Schematics (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 (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Circuit/System Verification
Ignition ON, press and release the steering wheel horn pad. The horns should sound and emit a clear and even tone only when the horn pad is pressed.
If the horns do not sound when the horn pad is pressed or continues sounding after the horn pad is released, refer to Horn Switch Circuit Test.
If the sound emitted from the horns are not clear and even, refer to Horn - Poor Tone.
Circuit/System Testing
Horn Switch Circuit Test
1. Disconnect the HORN relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
• If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
• If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the appropriate horn.
6. Test for less than 1 ohm between the ground circuit terminal 1 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the horn.
8. Connect a 20A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the horns are activated.
• If the horns do not activate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the horn.
9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Press and release the steering wheel horn pad. 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 ground. If the circuit tests normal, inspect for a sticking horn switch.
• If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, inspect for an open horn switch.
11. If all circuits test normal, test or replace the HORN relay.
Horn - Poor Tone
1. Ignition OFF, disconnect the harness connector at the appropriate horn.
2. Test for less than 1 ohm between the ground circuit terminal 1 and ground.
• If greater than the specified range, test the ground circuit for a high resistance.
3. Disconnect the HORN relay.
4. Test for less than 1 ohm between the control circuit terminal 87 at the HORN relay and the control circuit terminal 2 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 appropriate horn.
2. Install a 15A fused jumper wire between the control terminal 2 and 12 V. Install a jumper wire between the ground terminal 1 and ground. Verify the horn emits a clear and even tone.
• If the sound emitted is not clear and even, replace the horn.
Relay Test
1. Ignition OFF, disconnect the HORN relay.
2. Test for 60-180 ohm between terminals 85 and 86.
• If not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
• If not the specified value, replace the relay.
4. Install a 30A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohm between terminals 30 and 87.
• If greater than the specified range, replace the relay.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Within an Electrical Center) (Service and Repair)
* Horn Replacement (Notchback) (Horn Replacement (Notchback))Horn Replacement (Hatchback) (Horn Replacement (Hatchback))
* Steering Wheel Inflatable Restraint Module Replacement (Steering Wheel Inflatable Restraint Module Replacement)