For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC B2501 5A: Horn Switch Stuck

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Horn Switch Signal | B2501 5A | 2 | 2 | --
Horn Control | 2 | 2 | 1 | --
Horn Switch Ground | -- | 2 | 2 | --
Horn Ground | -- | 2 | 2 | --
1. Horn Always On 2. Horn Inoperative

### 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.

### Conditions for Running the DTC

When the output is actively being requested by steering wheel module.

### Conditions for Setting the DTC

The steering wheel module detects a short to ground in the horn switch signal circuit or a stuck horn switch for greater than 60 seconds.

### Action Taken When the DTC Sets

The horn will continuously sound until it is disconnected or when it overheats 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

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Horns System Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Ignition ON, observe the scan tool Horn Relay Status parameter while pressing and releasing the horn pad, the reading should change from On to Off.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the right steering wheel control switch.
2. Test for infinite resistance between the signal circuit terminal 2 and the low reference circuit terminal 1.

⇒ | If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, check for a sticking horn switch.

3. Ignition ON, verify the scan tool Horn Relay Status parameter is Off.

⇒ | If not the specified value, replace the right steering wheel control switch.

4. If all circuits test normal, replace the horn switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Steering Wheel Horn Switch Replacement

• | Control Module References for steering wheel module replacement, setup, and programming