EL020 ELECTRICAL

I am fitting a wiring harness to my 1955 mss 500, my prob. is when I switch to dim, parking, speed and rear light works also horn and brake light, but when I switch to main beam I get no rear light. if I loop across to get rear light to work I get main beam on both sides of the switch. I have been told it maybe a Vemon harness, if so would that be the prob. and how could I overcome it? - Reg Taylor 9/10/2004

The harness and the switch are the same on the early springer MSS and early Venom. However, the wiring harness colour coding changed drastically when Veloce changed from a Miller dynamo to a Lucas dynamo and/or a Lucas switch. The Lucas switch started with the Thruxton, initially with a Miller dynamo then a Lucas dynamo, and then the same set up spread to the later Venoms and MSS. So it's usually more a question of have you got the right harness for your make of dynamo and switch, and is it connected up exactly as in the diagram. You can see the differences in the wiring diagrams in our Tech Info section.
However, it is most likely that you've got the right harness and you've just mixed up the connections to the switch. It sounds like you've just connected the rear light wire and the speedo bulb wire to terminal 5 (the one that the side light wire connects to) rather than terminal 7. (Assuming a Miller switch)
If you have a Miller switch as originally on the 1955 MSS double-check the wires are colour coded as for the "VSL351M" harness described in the Tech Info section and that you've connected them to the switch terminals exactly as in the diagram. It's easy to mix them up and get symptoms like you describe. The VSL351M diagram shows the actual switch connections quite clearly. - TW 9/10/2004

My dynamo amp meter and switch are Miller. I still have the old switch with the numbers on and will re-fit it instead of the new one with no numbers. I was told my wiring harness was for Miller dynamo. - RT 11/10/2004

Good idea to try a "proper" Miller switch since you have one. You'll see from the diagrams what wire goes into which terminal.
Your current switch may be a defective copy of a Miller, or it may just work differently and/or be from something like an LE. But you might be able to work out its equivalent connections to the "proper" Miller if you've got a test meter or a small bulb and battery once you've got it on the bench. - TW 10/10/2004

thanks, i now have a successful lighting system,i fitted the old switch that has number's and followed the diagram - RT 12/10/2004