replace your battery.

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Battery replaced - no help

 

was the battery replaced back 5k miles when the problem last arose? may be a charging issue.

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From looking at the wiring diagrams in the Haynes manual, the items you list as failing appear to have a common Earth. No idea where it is, but you could be suffering from poor earthing on that circuit.

 

As far as I can recall the main earth is left side somewhere around the upper engine mount - I was told where it was but ultimately didn't have to look as I realised my problem wasn't related to that

 

I agree your view Mokkybear. ECUs earth (pin 3) is directly connected to battery minus and works fine. ZFE pin 5 should get earth via "point 31l" which is again connected to battery minus. Would be interesting to know the location of "point 31l" where a number of earth wires seem to meet.

 

https://plus.google.com/photos/111266577605871003300/albums/5840070657543245633/5889795856560728914?banner=pwa&pid=5889795856560728914&oid=111266577605871003300

This seems to be the location where the harness is connected to earth and positive. Need to check tomorrow.

 

That's the starter motor earth - I'd be surprised if everything went through there. You could disconnect it and see if everything else works except the starter, just to confirm one way or another.

 

Finally some progress. [] Voltage at the battery is fine after starting the bike (14.2-14.5), but after minute or two it starts climbing up, specially if reving or loading the engine. Voltage goes up to 15... 16... 17... The computer obviously has some self defense system and shuts down around 16V. If adding some load like handle bar heaters the voltage comes down below 15V and the computer and LCD display return to normal.

Either alternator or rectifier/regulator which I have no means to test or repair [!]

Taking the bike back to BMW dealer.

 

F800ST Altenator Stator Rotor



Hi

How did this turn out? I am sitting with a similar problem and have found it easy to test and find the problem. [8D] The test consists of testing battery, rectifier/regulator and finally the alternator/generator.

I also discovered that BMW only sell the alternator kit for A$1600 [!] which includes what seems to be a revamped rotor with large holes in it which the old one did not have. Apparently better to cool you with my dear. [err] My bike has 52000km on the clock. So decision is do I replace with part from Electrosport for US $200 and go for another 52000km or get new kit for Aus $1600 and ride for hopefully longer.

Your findings would be interesting.[]

 

Sounds like a rectifier/regulator problem - the alternator loses voltage when a field fails. Check all connections, but most likely it's a replacement job.

 

I helped a friend replace his stator ( alternator ) with the Electrosport a few years ago. No issues. BMW replaces both the stator and the flywheel, which as you pointed out now has larger holes for better cooling. The aftermarket stator has better windings which will stand up to the heat much better. I see no need to give BMW such an excessive amount of money for this part. I do think that since it is obviously an issue and they have changed the part for better cooling....they really could give customers a break on the replacement price.
Your original lasted all these years and 52K...the Electrosport part is much better....why spend any more. btw if you are handy at all it is an easy repair. Wiring plugs can be difficult to access and disconnect but the stator is mounted inside the engine cover with 3 machine screws.

 

Find it hard that the dealer did not find this voltage spike problem as it is a basic thing to check at the start of electrical fault finding. Me thinks they just plugged in the laptop and looked at what it said rather than doing any 'garage stuff'

 

Without being that familiar with their service PC, I'd have though voltage would have been one of the things the bikes computer recorded. If so they could be forgiven for simply plugging it in and looking for any alarms.
How reliable those fault code logs are is another matter entirely.......

 

I'm new here...just got myself a 2008 F800ST.

The LCD console went intermittently blank once the bike runs well.
When it cools down or slow down, it comes back on again.
It's similar to the problems described in this thread.

May I know how this item was resolved eventually?
Many thanks in advance.

 

Check you stator if it's bad Euroelectric in Denver

 

I agree - check the charging system including the rectifier/regulator. If the voltage to the battery rises with revs, then voltage to the instrument panel could be cutting out for protection.

 

VLT, Mokkybear...thanks, it's a little late.

 

Is it something like that? Any one have solution? I've checked controllers on dash and make some soldering... Nothing changed.

 

ero_, don't seem to understand your issue based on your video...

 

This issue is that, after shutting down bike my tacho turns on. Some time 1 or more repeat this issue.

If the weather is cold it makes this more often.

 

ero_, sorry but don't think that I can't help you here.

my issue 2yrs back was due to electrical overcharging by faulty rectifier. the faulty rectifier led to over-voltage which occurred only when the engine gets warmed up or is revving higher than 3k rpm. when this happens, the charging voltage goes high resulting in the console blanking itself out as a protection against over voltage. once the temp drops or the rev becomes low, the charging voltage drops below the safety threshold and the console works again. besides the console, the F800ST works fine...except for the blowing of the main headlight bulbs from over-voltage.

 

What did you end up doing? My 2012 F800ST has the exact problem. Bulbs blow in a few hours, speedometer loses power and goes to zero, main display shuts down. Importantly, the tach always works and the computer itself is NOT shutting down...it does NOT go through the initialization like it does when you start the bike. Just the display blinks off, sometimes for 30 seconds, sometimes for an hour. Bike runs great (except it is illegal to ride without a front light in my area) and everything else is fine. Stop or even slow down for awhile and the power comes back by itself.

 

Have you checked the battery connections? And also check for the earthing point of the dash. That sound is what you get if you disconnect a battery terminal then touch it back to the terminal.

 

I thinked so and make major cleaning and make some soldering at connection on dash board. I'll check ZFE connection point today.

At this point here in Turkey our weather come hot above 20 degree celcius and I think there is no problem for now.

 

Hi Ari,

Yes, a similar problem happened last year to my 2007 F800S.

While riding the display panel went blank and appeared moments later only to once again blank out. I worried as was in an isolated area far from help and hoped it would not cause a problem to the engine, however about 10 minutes later the engine lost and resumed power more and more often and was lucky to pull up to a fuel bowser in a small town. What to do as it needed fuel so had to turn it off....so it never fired up again..Anyway it was the coil which was faulting and causing the power losses. My not be your problem but similar.

Regards Simon