The electrical connections at the transmission had come loose. Tightening the center screw and using a couple spot ties to keep them together solved the problem. Bad or very weak batteries will cause the same problem
I had 2003 390 MY and it was located in the. Forward cabin syndrome side front cabinetry behind the forward panel. You can disconnect the supply line to the horn and add a few drops of light oil (hold it up to let the oil run down into the compresso...