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R75/5 Ignition Switch - Mystery Wire
R75/5 Ignition Switch - Mystery Wire
So, I opened the headlight, and as you might expect, there were a lot of melted wires. Most were melted together. I documented it as best I could with photos, but it wasn't a pretty sight. It looks like the worst came from the common ground wire connecting the idiot lights; however, it also went up into the right handlebar switch.
I replaced both handlebar switches from MAXBMW (love that place!). I also had to remove the ignition and light switch (those tabs are frightening!). So, as I'm looking at the switch, things are fairly straightforward except for one mystery wire. I can't find it documented ANYWHERE; however, I've seen it in online pictures... just no mention of what it goes to... and, it's in several different color configurations. On mine it's green, but I've seen it as white and white/black.
The actual wiring diagram from the original owner's manual shows that there are no white or white/black wires attaching to the ignition and light switch. Also, the only green wires I see illustrated all come from post 15, and include the common ground for the idiot lights (to flasher relay post 31), one going to the right ignition coil, and one going to the horn (post 15). Yet, I have this unidentified green wire, soldered to the switch, which is energized when the key is in the on position. It's looking kind of ragged, and I'll replace it... just need to know where the other end goes! Haha.
And, yes, I am labelling every wire with shrink wrap. I find that makes my life much easier down the road. I've attached 2 pics showing both sides of the switch. In both pics I have circled the connection spot in green and used an arrow to point to the wire. Any help would be greatly appreciated!!
Also, if there's any interest, I've got a spreadsheet (saved as a .pdf) that shows every wire and where it goes on this R75/5, including color and size. I'll gladly share it, if told where you'd like me to post it.
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- schrader7032
- Posts: 9062
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
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Dr. B - Welcome! I saw your
Welcome! I saw your post on the MOA forum...kind of forgot about it some. I've looked in my Haynes and the 30/51 post on the ignition switch board shows two wires attached to it. One solid red, fairly thick, going to terminal 30 on the starter relay. Another green wire with red stripes goes to terminal 30 on the lights/horn switch. As I recall, red wires are hot all the time, while green wires with red stripes are switched power.
Do you have anything currently going to that terminal on the horn switch? Maybe someone replaced the original green/red wire with solid green at some point.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
No, this wire isn't connected
in the first image, I've circled where the wire is soldered, so you can see it in relationship to the board. In the second image, you can see the proximity to terminals, but it is soldered. Any help is appreciated.
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That isnt a very good clean
twocams
92 R100RT/69 R69S
2004 Aprilia Atlantic 500cc single cylinder Scooter
83 Honda V65 Magna, fastest production bike in1983
2015 Can Am Spider SE6 1,688 miles
2018 Moto Guzzi V711 Special
not white (WS) but gray (GR)
the wiring diagram shows it from position 58, powering instrument illumination and parking lights.
The green wire at upper right on my board shown above runs power to the idiot lights (oil press, gen & neutral) horn, turn signal flasher relay, etc.
Two of my switch boards don't have the fuse holders - being from early /5s - otherwise they all look the same.
Have you looked at DIN 72552? https://en.wikipedia.org/wiki/DIN_72552
it indicates #58 is for "licence plate lights, instrument panel". Scroll down to Lights for that. I believe the DIN has been revised since '71, but usually all the little numbers near electrical connections describe the function through the DIN coding.
I'm interested in seeing your wiring spreadsheet. I'm assembling a '71 and the harness is just about next.
- Snakecharmer
- Posts: 7
- Joined: Sat Jan 20, 2018 1:44 pm
Headlamp wiring
Anyone got any information on how to assemble the headlamp switch itself?
Regards, in anticipation.
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Headlight wiring..
Re: R75/5 Ignition Switch - Mystery Wire
- r67boxer
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- schrader7032
- Posts: 9062
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
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Re: R75/5 Ignition Switch - Mystery Wire
https://bmwmotorcycletech.info/1973-electricals.pdf
https://bmwmotorcycletech.info/Slash5Schematic.jpg
Snowbum's website is available through the Knowledge Base link in the upper right.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.