Checking the output signal

Activate the horn.

HINT: Listen for a click from the relay to determine whether the fault is in the relay circuit or in the wiring for the horn itself. 

1. The horn is functioning

   OKAY:  Troubleshooting has been completed.

2. The relay clicks

   Refer to Checking the wiring for the horn 

3. The relay does not click.

   Refer to Checking the cable for the relay 

Fig 1: Identifying VCT2000 Diagnostic Tool Symbol In VIDA

Courtesy of VOLVO CARS OF NORTH AMERICA.