Battery positive voltage is applied at all times to the horn relay coil and horn relay switch. Pressing the horn switch applies ground to the horn relay control circuit. The body control module (BCM) also may apply ground to the horn relay control circuit. When the horn relay control circuit is grounded, the horn relay is energized and battery positive voltage is applied to the horn via the horn control circuit. The horn will sound as long as ground is applied to the horn relay control circuit.

Schematic Reference

Horn Schematics

Connector End View Reference

Horn Connector End Views

Electrical Information Reference

Scan Tool Reference

1. Press the horn switch. The horn relay should click and the horn should sound as long as the horn switch is pressed.
2. Turn ON the ignition. With a scan tool, command the BCM Horn Output. The horn relay should click and the horn should sound while commanded ON and stop sounding when commanded OFF.

1. Verify the horn mounting hardware is tightened to the proper torque. Refer to Fastener Tightening Specifications .

⇒	If the mounting hardware is not tightened to the proper torque, retorque the fastener to spec.

2. Ignition OFF, disconnect the harness connector at the horn assembly.
3. Test for less than 1.0 ohm of resistance between the ground circuit terminal A and ground.

⇒	If greater than 1.0 ohm, test the ground circuit for a high resistance.

4. If all circuits test normal, test or replace the horn assembly.

Install a 15-amp fused jumper wire between the control terminal B and 12 volts. Momentarily install a jumper wire between the ground terminal A and ground. The horn should emit a clear and even tone.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Horn Replacement