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Adapting a78r100 wiring loom to the bike, it was a73 r75/5 now it's more 78 r100 with a front drum. In be tween fits and starts everything has worked out ok. I'm chasing my tail trying to get the high beam indicator working as it should. Lights on low beam, high beam indicator comes on, on high beam also w.orks but slightly brighter. Using a dan Moto speedo tach, which apart from this problem works fine. The bike at this stage is non runner, a functioning high beam indicator is a roadworthy requirement as it will be on club plates. Using a circuit tester on the switch grip White has the power on low, and if you also touch the high beam (yellow) beside it I get a weak feedback through it enough to light up the led indicator in the speedo. I have probably done this all arse about face. It's something that you eventually stumble on, but I want to ride the bike while I can still chew solid food. Motor is r100, tank,seat and obviously headlight.

Regards to all for the coming festivities

r75bitsa wrote:Using a circuit tester on the switch grip White has the power on low, and if you also touch the high beam (yellow) beside it I get a weak feedback through it enough to light up the led indicator in the speedo.

Regards to all for the coming festivities

Sounds about right according to the wiring diagram. White goes to 56a on the board, yellow to 56b. Colour coded as you know.

I think I'd clean the connectors carefully first but only 'cause I don't know what else to do. (If you do this take care to do the switchgear in a big plastic bag or you'll lose the spring.) Maybe the white and yellow are rubbing somewhere???

G'day Steve
Yeah did that with the right hand side,what an adventure that was. Also in the diagram we see that white goes to high beam. Lights in the speedo are taken care of by the park light wire (grey/black) not sure whether it could be wires touching or some other mystical scenario that has you thinking you are a genius one moment and a gibbering mess the next.

Gidday Bitsa
The 78 R100 has the 'Light Relay', which adds complication and is of questionable value - something to do with turning off the headlight during starting. Is your loom set up for UK or US models? There are differences. Here is Snowbum's take on things (best of luck retaining your vision): http://bmwmotorcycletech.info/headlightrelay.htm

How are the low and high beams working? Do they appear to be distinct, as in low beam points down to the road and high beam points high (only)? If both beams appear to be on at either setting that would explain the idiot light being on. I advise scrupulous checking of ground connections. It gives you something to do while you are thinking.

If you are using the Haynes wiring diagram be aware that it is hard to distinguish between the Yellow wire (56b) and the Yellow/White wire (56), which feeds the High/Low switch. Confusing those will likely cause the problem too. Best of luck getting to the "Aha!" moment in a timely manner.

ps: Solid food is overrated.

I have an aha moment for you, further frustration - sorry investigation shows that when I thought how simple high beam indicator tap into the high beam wire nooooooo. Circuit tester found the bleed in the high beam wire when on low.. Seperaration of the wires found that when on low beam the was a bleed back from the fuse board, not forward from the switch. Sooooo does that mean that there is something going on there as the terminals are side by side they are in their proper slots. As the high beam works from the switch and they both have proper definitions in relations to function. Would it be like a duck on the water - all the action goes on underneath. The Haynes shows the White going to the high beam, is there a function in the old console that relates to that as iam not using it. All of the earth points and wires are good and you're right about solid food better using a straw. This is a uk loom no black wire.

Regards

Dunno about your duck.

The white wire is intended to be for high beam but I'm guessing you have swapped it for yellow? The original loom to the speedo/tach has a white wire going to the high beam indicator and earthing back through the loom to the board. I'd be inclined to go with the conventional wiring colours and layout and then tap off what you need for your instrument lights. The white zone on the terminal board has the extra pin to tap off from (there is even a bonus pin).

r75bitsa wrote: Seperaration of the wires found that when on low beam the was a bleed back from the fuse board, not forward from the switch. Sooooo does that mean that there is something going on there as the terminals are side by side they are in their proper slots.

Regards

I really don't know a thing about your switch. I do know that electricity takes the path of least resistance. And that there must be a difference of electrical potential for electricity to flow. Bleed back from the fuse board? Sounds like something is not grounded well enough.

I'd be checking grounding points with a test light.

Would that mean I could use a pilot, then run a white from the board slong with an earth to get the required result. At the moment I have a pilot and wires testing all options, slong with cleaning and tightening earths. I will try one of the white spares on the board. We'll see what happens then.

Would that mean I could use a pilot, then run a white from the board slong with an earth to get the required result. At the moment I have a pilot and wires testing all options, slong with cleaning and tightening earths. I will try one of the white spares on the board. We'll see what happens then.