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No power at dash

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ThompsonJP
Posts: 53
Joined: Thu May 22, 2014 11:45 pm

No power at dash

Post by ThompsonJP »

Hi,
I'm looking for some suggestions on what to try to chase down an electrical problem. Here are the basics of what's happening.
- 1974 R90/6
- Dyna III electronic ignition
- diode board replaced four months ago
- no power to dash or anywhere when ignition engaged
- battery has been tested and is good
- positive and negative connections are tight
- there was no build up to this problem, it just quit
Any suggestions would be appreciated. Electrical problems are my weakness/
Thanks
JPT

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schrader7032
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Location: San Antonio, TX
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First thing I'd check is that

Post by schrader7032 »

First thing I'd check is that you have power to the starter relay.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

ThompsonJP
Posts: 53
Joined: Thu May 22, 2014 11:45 pm

where to check

Post by ThompsonJP »

I'm not sure which wire or terminal to check. Do I pull the wire, apply the positive on the voltmeter and ground the negative?
I've attached the diagram from MotoElectrik.
Thanks
Attachments
relay-104_diagram.jpeg
relay-104_diagram.jpeg (21.97 KiB) Viewed 3056 times
JPT

ThompsonJP
Posts: 53
Joined: Thu May 22, 2014 11:45 pm

fixed

Post by ThompsonJP »

Well, I got inside the headlight bucket to check the fuses and discovered a suspect ignition connection. The hot one, I think. So, I cut back the wires, cleaned up the connector, threw it all back together. Now I have lights at the dash. All good.
Thanks
JPT

ThompsonJP
Posts: 53
Joined: Thu May 22, 2014 11:45 pm

spoke too soon

Post by ThompsonJP »

The bike was running. Then I came back this evening to fire it up again and got nothing but a click and screeching sound from the headlight bucket. (That stopped too after a bit.) This was with the headlight off, so I'm sure it was from in there. I'm just not sure what caused it.
Any advice on what to check next?
Thanks
JPT

ThompsonJP
Posts: 53
Joined: Thu May 22, 2014 11:45 pm

still stumped

Post by ThompsonJP »

I checked current to the starter relay, and I get the same reading as at the battery itself. Still, I don't have any dash lights, and of course no start or even noise at the relay.
So, I removed the diode board and have been trying to test it. I video I found from Moto Phoenix gave some tips but the board is new and I can't test it the same way as recommended.
I included photos of my diode board.
Any more recommendations?
Thanks
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img_20191102_180330429.jpg
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img_20191102_180313257.jpg
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JPT

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schrader7032
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The diode board is part of

Post by schrader7032 »

The diode board is part of the charging circuit. Basically it has nothing to do with the dash lights working or not. Just to be sure, have you check the kill switch on the handlebar?

If you follow the wiring diagram checking for voltage from the battery to the starter solenoid, you will likely some point where the 12v disappears which will tell you what the issue is. Snowbum has two lengthy articles on starter problems:

https://bmwmotorcycletech.info/boschvaleostarter.htm

https://bmwmotorcycletech.info/startingprobs.htm
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

ThompsonJP
Posts: 53
Joined: Thu May 22, 2014 11:45 pm

condenser broken

Post by ThompsonJP »

I'n trying to follow the wiring diagram and find the problem. However, in taking off the front cover, I discovered that the connection to the condenser is broken off. I have electronic ignition, so I'm not sure if that is bypassed anyway. Would it make sense to order a new condenser, since my bike still has points installed and could be used as a backup.
Thanks again.
JPT

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schrader7032
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The Dyna III doesn't use the

Post by schrader7032 »

The Dyna III doesn't use the condenser. I have the same set up on my /7. But, yes, you need a working condenser if you ever have to shift back to the stock ignition.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

ThompsonJP
Posts: 53
Joined: Thu May 22, 2014 11:45 pm

Problem solved

Post by ThompsonJP »

After checking a bunch of connections multiple times, I finally opened the headlight bucket again. One a wire leading to the ignition switch was a crappy connector I was suspicious of. I turned on the ignition, wiggled it, and sure enough my dash lit up. So I took it off, soldered the connection and heat shrunk it. Works fine now.
Thanks for the suggestions.
JPT

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