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Topic-icon Neutral light comes on when clutch lever is pulled in

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1 month 1 week ago #6466 by 7620
After replacing the neutral safety switch on my '78 R80/7 the neutral light comes on every time the clutch is disengaged. It didn't do that before I replaced the switch.
Everything else works properly. Is this normal? If not, I would appreciate suggestions as to what I might have done wrong!

Thanks for any help!

Jon
1978 R80/7
2006 FJR1300
USMC '62-'65
Retired MSF Instructor

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1 month 6 days ago #6472 by murphyam53
A little background information here might be useful. The neutral safety switch in the transmission allows the starter relay to be energized only when the transmission is in neutral. The neutral light will indicate this. The switch at the clutch lever will override this interlock and allow the starter relay to be energized when the clutch lever is pulled in. A diode on the back side of the interconnect circuit board in the headlight bucket prevents the neutral light from lighting when the clutch lever is pulled in, but the transmission is not in neutral.
You are a little unclear if you replaced the switch at the transmission or the switch at the clutch lever. If you replaced the transmission switch, and it does indeed indicate neutral when it should, that's not the problem. If you replaced the clutch lever switch, you most likely connected the brown/yellow lead to the brown terminal on the interconnect circuit board. Moving that wire to the brown/yellow terminal moves the clutch switch to the correct side of the diode. There is the possibility that the diode is shorted internally. You can test it with an ohmmeter. See bmwmotorcycletech.info/electricalhints.htm for lots of information on this issue.
Let us know what you find, we can fix this annoyance.

Andy
ABC# 15601
1995 R00RT

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1 month 6 days ago #6473 by 7620
Thanks for the quick and very informative reply.
I did replace the clutch lever switch, but didn't get into the headlight. There was a plug outside of it. Part of the problem is that I only had the bike a short time before replacing the two switches and I don"t remember if it did this before.

I checked today and the brown/yellow wires go the brown/yellow terminals on the board so I guess that narrows it down to the diode unless there is something else I have missed.

I appreciate the help. I'll keep you updated.

Jon

Jon
1978 R80/7
2006 FJR1300
USMC '62-'65
Retired MSF Instructor

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