The horn is just a switch which grounds the wire plugged into the back. The little wire should run to the coil of a relay with battery +12V on the other side of the coil. This relay then switches the horn. So the little wire should read +12V normally. Not sure where the relay should be on a MK3, but you can always wire a new one up yourself.
Wed, 12 October 2005 23:17
