bobyoungATntlworldDOTcom

Thanks Chris. After some serious disassembly I have removed spotlamps & foglamps and all associated wiring, relays and switches. Following your advice to look at earlier years things began to look a little clearer. I also cut the harness open along the inner wing to find the extent of burned cable. Didn't have to go far till I found main beam (LH) loops back and into 'step relay' near battery. I removed this and after close examination found that the base was partially melted, allowing contact to 'fall over!'. This locked the rocker in one position, not in contact with either circuit... SO tomorrow I am going to get a replacement step relay, and some new cable etc. and hopefully all will be well. The fault I believe originated in Spotlamp which was wired direct into LH main beam supply side. I am an electronics engineer by trade so this has been so frustrating. However I think I now understand how the whole thing works except for what is in the bulb failure unit. This appears to be an integral part of the dip beam circuit. I am probably now in a position to help others with this type of problem, it having kept me awake at night for some days.. Thanks for your good advice. The earlier diagram was the clincher.

Bob.