For 1990-2009 cars

### Diagnostic Fault Information

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

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Horn Relay Control | B2750 00 | B2750 00 | B2750 00 | --
Horn Control | 2 | 2 | 1 | --
Horn Ground | -- | 2 | -- | --
Horn Switch Ground | -- | 2 | -- | --
1. Horns Always ON 2. Horns Inoperative

### Circuit/System Description

When the horn button is pressed, ground is applied through the horn switch contacts and the horn relay control circuit to the coil side of the relay. The horn relay coil is then energized, causing the relay switch contacts to close applying voltage through the horn control circuit to the horns. For theft deterrent functions, the body control module (BCM) also controls the horn relay by applying ground to the relay control circuit to the relay.

### Reference Information

#### Schematic Reference

Horn Schematics .

#### Connector End View Reference

Component Connector End Views .

#### Electrical Information Reference

• | Circuit Testing .

• | Connector Repairs .

• | Testing for Intermittent Conditions and Poor Connections .

• | Wiring Repairs .

#### Scan Tool Reference

Control Module References

### Circuit/System Verification

Ignition ON, use scan tool Horn output control to command the horn relay On. The Horn Relay Command output data parameter should display On and both horns should sound.

### Circuit/System Testing

1. Ignition OFF, test for less than 1.0 ohm of resistance between the inoperative horn ground circuit terminal A and ground.

⇒ | If greater than 1.0 ohm, test the ground circuit for an open/high resistance.

2. Test for voltage at the inoperative horn connector B.

⇒ | If voltage is present, replace the inoperative horn.

3. Repair the open or high resistance in the horn control circuit.

### Repair Instructions

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

Horn Replacement