1975 BMW R75/6: Replacing Left Side Handlebar Switch

I had to replace this switch and decided to document “what wire goes where” inside the headlight shell on the circuit board and to the ignition switch and headlight relay.
I also explain how to map information found in various wiring diagrams to the labeled areas on the circuit board. There are some places where things got confusing for me in going between the various published wiring diagram(s) and the circuit board inside the headlight shell, so I hope this material helps others avoid being confused.
You will find this write-up here:

Here are a couple pictures from the write-up.

Broken Left Side Headlight Switch

Broken Left Side Headlight Switch

New Switch Assembly with (8) Wires

New Switch Assembly with (8) Wires

Wiring Circuit Board Inside Headlight Shell [Source: MAXBMW]

Wiring Circuit Board Inside Headlight Shell [Source: MAXBMW]

Green/Black Wire Is A Ground Wire-Goes to Brown Section of Circuit Board

Green/Black Wire Is A Ground Wire-Goes to Brown Section of Circuit Board

4 thoughts on “1975 BMW R75/6: Replacing Left Side Handlebar Switch

  1. Hi Brook,

    Once again your help in my own project has been tremendous as you’ve just made me realise I have a shorted neutral diode! Now I just have to get to it…

    Anyhow I wondered when you were talking about ground on the circuit board…you say area 30, but do you mean 31? Area 30 is the permanent, unswitched live positive feed isn’t it?

    Once again thanks for all your great advice, photos and the massive amount of time you must invest in creating such a useful knowledge base.

    • Hi Matt,

      Ah, thank you for catching my “fat finger” mistake. Of course you are correct, it is “Area 31”. I’ve made the edits. I appreciate you finding the mistake for me.

      Best.
      Brook Reams.

  2. Hi Brook, Sorry to hear about your recent scrape on Gonzo….I suppose that will give you something to do in the future when you run out of bikes to beautifully rebuild?! I thought you had replaced the left side handlebar switch on Gonzo but it was the /6 so it took me a while to find this entry. My /7 hi/low beam switch has seized up from the Indian dust/not enough use and am wondering about dismantling and cleaning. I notice you attempted something similar but purchased a new one in the end. Did you take any photos during dismantling the Hella switchgear? There must have been something pretty difficult in there for you to abandon the original unit. Can’t find much else online about it, so any advice on whether I should open it up or not would be great. Feel free to use my email address if needed. Thanks in advance, Matt

    • Hi Matt,

      Thank you for your kind note.

      I was unable to get the spring and ball mechanism to operate correctly and damaged the spring in the process, so I bought a replacement switch assembly.

      If you attempt a repair, put the switch inside a baggy and then take it apart so any small parts and the spring don’t go missing.

      Best.
      Brook.

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