Diagnostic Routine A

Diagnostic Routine A

Diagnostic Overview

The Horn Is Inoperative

Refer to Wiring Diagram Set 44 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

REFER to Horn Operation .

Visual Inspection and Diagnostic Pre-checks

Inspect the BCM (Body Control Module) fuse 22 (20A).

Pinpoint Test

1. CHECK THE BCM (Body Control Module) OUTPUT

1. Ignition ON.

2. Using a scan tool, view BCM (Body Control Module) PIDs (Parameter Identifications).

3. Select the BCM (Body Control Module) active command PID (Parameter Identification) HORN. Command the horn on and then off.

Does the horn sound when commanded on?








2. CHECK FOR VOLTAGE TO THE SCCM (Steering Column Control Module)

1. Ignition OFF.

2. Disconnect: SCCM (Steering Column Control Module) C2414A.

3. Measure:





Is the voltage greater than 11 volts?








3. CHECK THE HORN RELAY COIL GROUND CONTROLLED CIRCUIT FOR AN OPEN

1. Disconnect: BCM (Body Control Module) C2280B.

2. Measure:





Is the resistance less than 3 ohms?








4. CHECK THE CLOCKSPRING GROUND CIRCUIT FOR AN OPEN

1. Disconnect: Clockspring C218A.

2. Measure:





Is the resistance less than 3 ohms?








5. ISOLATE THE STEERING WHEEL HARNESS

1. Connect: Clockspring C218A.

2. Remove the driver air bag module. REFER to Driver Air Bag Module .

3. Disconnect: Clockspring C218B.

4. Connect: Battery Ground Cable.

5. Measure:





Is the voltage greater than 11 volts?








6. CHECK FOR VOLTAGE THROUGH THE CLOCKSPRING

1. Measure:





Is the voltage greater than 11 volts?








7. CHECK FOR AN OPEN IN THE CLOCKSPRING

1. Remove the clockspring. REFER to Clockspring .

2. Measure:





Is the resistance less than 3 ohms?








8. CHECK FOR VOLTAGE AND GROUND TO THE HORN

1. Disconnect: Horn.

2. While activating the horn, measure:





Is the voltage greater than 11 volts?








9. CHECK FOR VOLTAGE TO THE HORN

1. While activating the horn, measure:





Is the voltage greater than 11 volts?








10. CHECK THE BCM (Body Control Module) HORN OUTPUT CIRCUIT FOR AN OPEN

1. Ignition OFF.

2. Disconnect: BCM (Body Control Module) C2280E.

3. Measure:





Is the resistance less than 3 ohms?








11. CHECK FOR CORRECT BCM (Body Control Module) OPERATION

1. Disconnect and inspect all BCM (Body Control Module) connectors.

2. Repair:

- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary

3. Reconnect the BCM (Body Control Module) connectors. Make sure they seat and latch correctly.

4. Operate the system and determine if the concern is still present.

Is the concern still present?








12. CHECK FOR CORRECT SCCM (Steering Column Control Module) OPERATION

1. Disconnect and inspect all SCCM (Steering Column Control Module) connectors.

2. Repair:

- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary

3. Reconnect the SCCM (Steering Column Control Module) connectors. Make sure they seat and latch correctly.

4. Operate the system and determine if the concern is still present.

Is the concern still present?