GM Service Manual Online
For 1990-2009 cars only

When the horn switch is depressed, the coil side of the horn relay is grounded. This action results in the following conditions:

    • The relay is energized.
    • The switch side of the relay closes.
    • Battery voltage is applied to the horns.

The body function controller also grounds the horn relay in order to produce a horn chirp. The horn chirp confirms the locked state of the door locks. The horn will also sound when the panic button is depressed on the remote door lock transmitter key fob.