B2750

DTC B2750

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of this diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor
DTC B2750 01
- Horn Relay Control Circuit Short to Battery

Diagnostic Fault Information





Circuit/System Description

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.

Conditions for Running the DTC

The BCM monitors the voltage level on the horn relay control circuit whenever the ignition is in the RUN position.

Conditions for Setting the DTC

The BCM will set DTC B2750 as current whenever an improper voltage level is detected on the horn relay control circuit for more than 15 seconds.

Action Taken When the DTC Sets

The BCM will disable the driver for the horn relay control circuit whenever DTC B2750 is set as current.

Conditions for Clearing the DTC

DTC B2750 will clear when an improper voltage level is no longer detected on the horn relay control circuit, or when a scan tool is used to clear DTCs.

Diagnostic Aids

Inspect for a sticking horn pad or horn switch.

Circuit/System Verification

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.

Circuit/System Testing

1. Ignition ON, install a scan tool.
2. Remove the horn relay.
3. Connect a test lamp between the battery supply voltage circuit and the horn relay control circuit.
4. Verify the test lamp turns ON and OFF when using the scan tool to command the horn relay.

• If the test fails to illuminate, test the horn relay control circuit for a short to voltage or an open. The horn relay control circuit includes the steering wheel coil assembly and horn switch. If the circuit/connections test normal, replace the BCM.
• If the test lamp remains illuminated at all times, test the horn relay control circuit for a short to ground. The horn relay control circuit includes the steering wheel coil assembly and horn switch. If the circuit/connections test normal, replace the BCM.

5. If all circuits test normal, test or replace the horn relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Inflatable Restraint Steering Wheel Module Coil Replacement
* Relay Replacement (Attached to Wire Harness) Relay Replacement (Within an Electrical Center)
* Control Module References for BCM replacement, setup, and programming Programming and Relearning