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Mother board or main wiring panel in /6 headlight assembly


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Does anyone out there know the significance of the color scheme on the main electrical board in the /6 headlamp assembly? The board is divided into three zones that I can tell; red yellow and green? I am trying to figure out why my speedo and tach do not have lighting to them. The center row of warning lamps all work except for the turn signal idicator and that is based on the position of the euro switch, but that is a defferent stroy.


When I opened the headlamp I noticed a green wire with balck stripe not connected. In research that I have done so far, I have identified this as the instrument lighting power source but do not know where to plug it in.


Any help is appreciated.



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I spent a long time today loking inside the headlight assembly. There way more than three zones and they all make sense now. They are color coded to match the wires that are connected to it. The only problem is that one of the previous owners did some improvising and things are not where they should be. It will take a while to figure this one out.....


Not all of the connections on the cable going to the instrument cluster have power. The only ones that do are # 1, 3, 8, 10 and 12. #10 does not have an associated post to plug into it, but has power. Something is amiss...

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Thanks Larry! That is so much nicer than the one in the Clymer manual. I had the assembly apart on Saturday and it seems pretty straight forward with wire colors and board markings/colors. There have been several mods in the headlight bucket though so I have to figure that out. I may just put it all back to stock and start over.

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  • 2 months later...

After a month of trying to figure all of this out, I gave up and brought the bike to Rick Jones of Motorad elektic. It has taken Rick some time, but he has solved my issues. The wiring colors on the replacement handlebar swithces do not match the original BMW wire color so that was the issue with the horn.


The instrument lighting failure was due to a faulty ground in the main wiring harness that he is fixing by installing an additional ground.


I hope to have her back and ready this weekend.


I took the liberty to treat the tank with POR 15 while he had the bike. It was a pretty simple process, but messy and time consuming and the sealant does not come with any type cleaner after it has set for a few minutes. I am very happy with the outcome and am now waiting the 96 hours for it to completely cure before adding fuel.


All I need now is a paint job and she will look as good as new!

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