Morning all. I have a frustrating problem.  I have a phase 1.5 , 1989 1.6gti. Horn  and rear window heater are not working.  Changed fuse (no.8), no joy. Switched relay (green 1 on far roght of board) with same 1 on other side of fuse board,  no joy. Relay clicks as it should.  Light on rear window heater switch works but goes out when you push button.  Does anyone know what's going on?  Thanks.  Stephen