DTC 524213-1 - Horn Alarm Output Driver OC

1- HORN OUTPUT DRIVER SHORT TO BATTERY
2- HORN OUTPUT DRIVER SHORT TO GROUND
3- HORN OUTPUT DRIVER OPEN CIRCUIT
4- VSM FUNCTIONAL FAILURE

If DTC 524213-1, go to Cause 3

CAUSE 3 - HORN OUTPUT DRIVER OPEN CIRCUIT
PROCEDURE OR ACTION:
1. Turn truck power OFF.
2. Disconnect the indicated connectors at horn and VSM.
3. On the DMM, select ohms scale. Verify DMM zero reading.
4. Measure resistance between the horn output driver pins at each of the indicated connectors.
Is resistance less than 0.5 ohms?
YES: Go to Cause 4.
NO: The horn output driver wire is shorted to ground. Locate and repair/replace shorted wire/connection.

CAUSE 4 - VSM FUNCTIONAL FAILURE
PROCEDURE OR ACTION:
1. Turn truck power OFF.
2. Reconnect harness connectors to horn and VSM.
3. Turn truck power ON and check DTC display.
Did DTC reoccur?
YES: Replace the VSM.
NO: Problem corrected. Resume operation.

Basically Cause 4 is VSM failure if previous check and repair does not fix problem.