B2750

DTC B2750

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.

DTC Descriptors
DTC B2750 01
- Horn Relay Secondary Circuit Short to Battery

DTC B2750 02
- Horn Relay Secondary Circuit Short to Ground

DTC B2750 04
- Horn Relay Secondary Circuit Open

Diagnostic Fault Information





Circuit/System Description

The body control module (BCM) provides a ground for the Horn PCB relay within the underhood fuse block. The underhood fuse block will then provide B+ voltage to the horn control circuit, sounding the horns.

Conditions for Running the DTC

When the horn output is actively being requested by the BCM.

Conditions for Setting the DTC

B2750 01

The BCM detects a short to voltage in the horn relay control circuit.

B2750 02

The BCM detects a short to ground in the horn relay control circuit.

B2750 04

The BCM detects an open/high resistance in the horn relay control circuit.

Action Taken When the DTC Sets

B2750 01, B2750 04

The horns will be inoperative.

B2750 02

The horns will sound continuously until the horns are disconnected or when the horns overheat and becomes inoperative.

Conditions for Clearing the DTC

* The DTC clears when the fault is no longer detected.
* The current DTC will become history when the request for the output is removed.
* The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.

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)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Ignition ON, command the Horn Relay ON and OFF with a scan tool. The horns should turn ON and OFF when changing between the commanded states.

Circuit/System Testing

1. Ignition OFF, disconnect the X2 harness connector at the X50A underhood fuse block.
2. Connect a test lamp between the control circuit terminal 20 and B+.
3. Ignition ON, command the Horn Relay ON and OFF with the scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

• 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, replace the K9 BCM.
• If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K9 BCM.

4. If all circuits test normal, replace the X50A underhood fuse block.

Repair Instructions

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

* Accessory Wiring Junction Block Retainer Replacement (Removal and Replacement)
* Control Module References (Programming and Relearning) for BCM replacement, setup and programming