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Author Topic: Starter diode  (Read 1148 times)

Dizerens5

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Starter diode
« on: December 12, 2011, 07:37:13 AM »
A while ago this forum identified for me the cause of a strange malfunction in the neutral light and starter operation on my 79 -- I had a failed diode, under the tank in the starter control circuit. So I bought a new diode from Motorworks and took off the tank to instal it. I looked under that tank until my back creaked, with the brightest light I could find. No diode. Yet it's fairly big (1 1/4 inch long, 1/4 inch wide) and should be easily visible. Can anyone tell me where to find it? The only clue I have is that its wiring out of the control relay enters the harness going towards the back, not the front as I'd expect. But no, it's not behind the right side panel.

Offline Bob_Roller

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Re: Starter diode
« Reply #1 on: December 12, 2011, 08:40:27 AM »
It's hidden in the wiring harness under the black cloth tape 'somewhere' !!!!!!

Like you said, it's fairly large, inspect the harness for an unusual lump .
'81 R65
'82 R65 LS
'84 R65 LS
'87 Moto Guzzi V65 Lario
'02 R1150R
Riding all year long since 1993 .
I'll give up my R65, when they pry my cold dead hands from the handlebars !!!!!

Offline nhmaf

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Re: Starter diode
« Reply #2 on: December 12, 2011, 10:52:17 AM »
Yes, unfortunately you'll likely have to remove a fair amount of that cloth tape to find it - would have been nice if they left it somehow visible/identifiable
Airhead #12178 ? BMWMOA #123173 ?BMWRA #33525 ?GSBMWR #563 ?1982 BMW R65LS ?1978 BMW R100/7 1998 Kawasaki Concours

Dizerens5

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Re: Starter diode
« Reply #3 on: December 12, 2011, 10:59:12 AM »
Good grief! That's the strangest way of installing a component I ever heard of. Even Joe Lucas didn't do that! It sounds as though it might be easier, or anyway less messy, to bypass that bit of wiring. Connections might be difficult. I'll take another look. Fortunately engine still starts (but only by holding the clutch).

Offline Barry

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Re: Starter diode
« Reply #4 on: December 12, 2011, 11:48:05 AM »
On 78-80 R65's the diode is supposed to be in the wiring harness close to the starter relay.  Follow the Brown/yellow wire from terminal 85 on the starter relay.

Post 81 models had the diode built into the relay.
Barry Cheshire, England 79 R45

Dizerens5

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Re: Starter diode
« Reply #5 on: December 12, 2011, 01:44:30 PM »
Thanks everyone. This forum is better than any classroom I was ever iin.

Offline nhmaf

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Re: Starter diode
« Reply #6 on: December 12, 2011, 04:00:16 PM »
I would imagine that the diode would be somewhere in the first several inches of wire leading from the relay, but they wouldn't have put it where there was a sharp bend in the harness, so it could be  further back.

Diodes fail, but with relative rarity in this low voltage/low current type of application, so I can sense the reasoning behind them just taping it up with the wiring.  But still, for posterity's sake, it would have been much nicer to have left it in a more identifiable manner.

Airhead #12178 ? BMWMOA #123173 ?BMWRA #33525 ?GSBMWR #563 ?1982 BMW R65LS ?1978 BMW R100/7 1998 Kawasaki Concours

Dizerens5

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Re: Starter diode
« Reply #7 on: January 07, 2012, 08:49:05 AM »
Just for info. I did find the diode in the end. For anyone else needing to look for it, it's right under the regulator, buried in the harness, but you can feel its outline. There's very little room to work. I hacked an opening in the harness with a very small very sharp penknife. Separating the spade connectors which hadn't been disturbed for over 30 years needed a really good pull -- which caused the original diode casing to fall apart. So you can see the diode itself, it's tiny. Fitting the new one was finger-breaking too but all works fine now. Thanks again for the help!

Offline Barry

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Re: Starter diode
« Reply #8 on: January 07, 2012, 09:53:34 AM »
I'll know where to look now if mine ever goes.

Thanks. That's good information.
Barry Cheshire, England 79 R45