BMW Problem, some serious thinking needed....

[England-Kev]

So armed with my trusty multi-meter, and a cup full of enthusiasm (for enthusiasm, read coffee) I headed out to my little lock-up, and the faulty beemer waiting inside.

So the battery, as it sat having not been played with for a week, has a voltage of 12.98V. So all good there then.

next was to check the voltage with the bike running, well this was harder to do as the bike struggles to run, but perseverence wins through, and the battery tops out at a charge rate of 13.95v or very near to that. so that too is in the ball park.

my next move was to pull the plug from the electronic regulator, now this cured the problem, the bike was back to running perfectly again. So I pulled the regulator from the frame and installed my old good mechanical regulator. This put the fault back into play, so we now know it is nothing to do with either reg.

Next I removed the battery lead, and took off the front cover, pulled the big lead from the diode board, started the bike and it ran great again. So I removed the diode board completely, but could find no outward signs of a problem. So I cleaned all contact faces, for the push on connectors, and reinstalled the board, but the fault was still there.

So I am guessing I have a failed diode board?

 

[Rob Farmer]

Seems to be a common problem at the minute. Mine failed so I pulled the front cover on my 100/7 to pinch the diode board from it only to find the front circuit board cracked on that one. Two diode boards needed it's the first time in all the years I've been riding airheads that I've had a diode board problem.

 

[England-Kev]

Well my next plan of attack is to buy a used board from MW's if they have one, so I can be sure that I have isolated the problem (I would borrow one if I could, but can't find anybody with a spare) if it is the diode board, then I shall invest in one of the new high power units. if not then I guess it will be the bean can. but I need to find the root of the fault before splashing loads of cash.

 

[Uncle-Fester]

Any news on this?

Seems to have gone a bit quiet......

 

[Roger Chatterton]

Hi England Kev-
I think I have both a spare diode board and beancan that you'd be welcome to borrow to check your system. Diode board was working fine when it was removed, to make way for an EME alternator etc. Beancan purchased for a spare - just in case !!
Drop me a PM and thenEmail me if I can help. I'm based in Cambs, but could meet up half way somewhere perhaps ( you buy the coffee and sticky buns ......)

Roger

 

[England-Kev]

Thanks Roger...

I attached a new diode board this morning, and double checked all the earth connections, but I still have the same fault? This leads me to the conclusion that the bean can must be screwed.
But if it is the bean can, why then would the bike run smooth with either B+ from the diode board, or the plug from the regulator disconnected?


I am confused by the fault

 

[Roger Chatterton]

Points to the regulator I think?
Or a short to ground on wiring loom?
Check for bent pins on connectors and try moving looms/ wiring
with engine running.
Do you have a known working regulator to swap out for existing?
Very hard to diagnose without being next to your bike!

 

[England-Kev]

Already swapped reg, no difference? can't check with bike running, as I can't keep the bike running

 

[England-Kev]

Anybody close to Reading with a spare ICU, I could try on the bike?

 

[England-Kev]

So yesterday I won a a good working used bean can and matching ICU on ebay for a great price (under £70, for the pair) this morning I fitted them both (I know you guys would like me to have fitted them one at a time) anyway, I bolted them on, and hit the button, and it runs

I now have to sort out the timing, as I fitted it by eye, but right now it is again running.

So a big thank you to all those who really took the time to help me work through the problem, and those who offered me parts. Have a virtual beer on me.

I will now send both the ICU's that I have up to Rob, so he can check them out for me on the tester, then we will know if it was just a second faulty ICU or the bean can.

 

[chrisshrops]

good new matey ,i hope it all works out for you