Diagnostic Test

1) DTC IS ACTIVE
NOTE: If P0562-BATTERY VOLTAGE LOW or P0563-BATTERY VOLTAGE HIGH is set along with this DTC, diagnose the battery voltage DTC first.

Ignition on, engine not running.

With the Scan Tool, select View DTCs in the Steering Control Module.

Is the DTC status Active at this time?

Yes
1. Go to step 2).
No
1. Go to step 7).
2) (X3) HORN SWITCH SIGNAL CIRCUIT SHORT TO (X903) HORN SWITCH RETURN CIRCUIT

Fig 1: Measuring Resistance Between Horn Switch Horn Switch Return Circuits
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Remove the Driver Airbag in accordance with the Service information.

Disconnect the Horn Switch harness connector.

Disconnect the Right Steering Switch harness connector.

NOTE: Before proceeding, thoroughly inspect the wiring harness and connectors between the Horn Switch and the Right Steering Switch for a short to ground or any other circuit.

Measure the resistance between the (X3) Horn Switch circuit and the (X903) Horn Switch Return circuit.

Is the resistance below 5.0 ohms?

Yes
1. Repair the (X3) Horn Switch circuit for a short to the (X903) Horn Switch Return circuit.
No
1. Go to step 3).
3) (X3) HORN SWITCH SIGNAL CIRCUIT SHORT TO GROUND

Fig 2: Measuring Resistance Between Horn Switch Circuit And Ground
Courtesy of DAIMLERCHRYSLER CORP.

NOTE: Before proceeding, thoroughly inspect the wiring harness and connectors between the Horn Switch and the Right Steering Switch for a short to ground or to any other circuit.

Measure the resistance between the (X3) Horn Switch circuit at the harness connector to the Right Switch and ground (include the metal casing at the back side of the Airbag).

Is the resistance below 5.0 ohms?

Yes
1. Repair the (X3) Horn Switch circuit for a short to ground.
No
1. Go to step 4).
4) HORN SWITCH

Fig 3: Measuring Resistance Between Horn Switch & Horn Switch Return Circuits
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance between the (X3) Horn Switch circuit and the (X903) Horn Switch Return circuit at the harness connector to the horn switch.

Is the resistance below 5.0 ohms?

Yes
1. Replace the Horn Switch in accordance with the Service Information.
No
1. Go to step 5).
5) RIGHT STEERING SWITCH
Turn the ignition off.

Replace the Right Steering Switch in accordance with the Service Information.

Turn the ignition on.

NOTE: The C206 (LIN bus) connector must be connected for this test.

Press and release the Horn Switch several times.

With the Scan Tool, Clear Stored DTCs in the Steering Control Module.

With the Scan Tool, select Data Display and view the Horn switch data.

While monitoring the Horn switch data, press and release the Horn Switch several times.

Does the Horn switch data change from Set to Not Set when the switch is pressed and released?

Yes
1. Test Complete.
No
1. Go to step 6).
6) STEERING CONTROL MODULE (SCM)
View repair.

Repair
1. Replace the Steering Control Module (SCM) in accordance with the Service Information.
7) INTERMITTENT HORN SWITCH INPUT CIRCUIT/PERFORMANCE DTC
The conditions necessary to set this DTC are not present at this time.

Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.

While monitoring the scan tool data relative to this circuit, wiggle test the wiring and connectors.

Look for the data to change or for the DTC to reset during the wiggle test.

Were any problems found?

Yes
1. Repair as necessary.
No
1. Test complete.