BMW K bikes (Bricks)


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Simon

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Any suggestions much appreciated. Have traced a draining battery problem to fuse #5 on my 1991 K100RS. There is a very minor draw (shows .01 volts) across fuse #3 also. Where is the problem? This is a brand-new Deka 30AH gel cell, BTW. Everything seems to run and operate fine, but the battery will drain when sitting, key out, and of course there is current when I connect the ground cable, key out. Thanks!

    

charlie99

charlie99
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0.01 volts drop accross the fuse ..could be significant simon im hoping that is with the fuse removed from the carrier.... if it isnt i would be putting the multimeter on to current settings and remeasuring with the fuse removed (just on the contacts )

the clock is always active ....but there must be something else drawing current somewhere ....like maybe a taillight globe or something connected and on, but not enough light escaping from it to show its still on....(happpens when they turn black on the inside but draw less but still some current )

i thought the main ignition switch has a number of positions ...position 1 turns on the parking lamps second position turns on the main power ...could there be some leakage accross the switch drawing some current ...but not enough to see whats still on ?

other wise ...heres a thought .....if your alternator has a blown diode internally ...it may draw current and not be metered or fused


might be better to remove either the positive or negative from the battery and measure the current draw ... try to isolate the wire drawing the current and chase it


heres a link to the fuse layout on some kbikes .......not sure if its the same
http://k100rt.aforumfree.com/t2058-fusebox-layout
good luck

    

Simon

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Clarification: measurement across the fuse-box terminals (with all fuses removed) = about battery voltage 12+ volts across terminals at fuse position #5 (with all fuses removed), and 0.01 volts at fuse position #1 (with all fuses removed). These values are obtained with the instrument cluster removed, to get the clock out of the system. All lights and bike functions are working normally when up and running, i.e. the 4-way flashers, turn signals, high and low beams, horns, etc. From the Clymer manual it looks to me as though fuse #5 is dedicated to the alarm system socket (unused, in my case) and to another ("special") socket I'm not clear about. Anybody know where these are physically located on this model? (1991 K100RS 16-valve). Thanks.

    

charlie99

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ok 0.01 volts across the contacts of the fuse holder means there is no load ....that is there is nothing to draw current at this time
if it was 12.0 volts or so that would mean there is some load

you should be using the current/amps range to check for active losses
reminder to remove the cables at the positive battery terminal
put the red lead to the battery positive the black lead to the terminals that feed the wires and see what you get

to me it sounds like someone has installed a relay somewhere ....and wired it to be always active instead of switched through the ignition switch (about 50 milliamps )
but we really need more information
how long does it tke to discharge the battery ..a few hours .. a week ....overnight ?

good luck

    

K-BIKE

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You must measure using current not volts. If you have a nifty fuse / meter adaptor you can measure each fuse drain one by one writing down what you measure on each.

The other way is to take one of the battery leads off and measure there so you can see total drain, write down the value and pull fuses one by one writing down any change when a fuse is pulled and leaving out the pulled fuses.

When you pull the last if there is still a drain you have an unfused drain which is not good. Trace back from each fuse which showed a change and that way you should be able to identify the device that is drawing. Tell us what you find and we can go from there.

A problem with 2nd hand bikes and cars is often there has been someone there before you tweaking, twiddling and fiddling.
REGARDS,
K-BIKE

    

Simon

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Problem "solved"? Okay, I got a new multimeter with an amperage function that works, removed all fuses and put the meter inline between battery and ground, determining that there was a 0.8 amp current with just the top fuse installed. That's a R/Y = red and yellow wire, which supplies the relay for the Motronic unit. Removed that fuse, installed just #5 (R/W = red and white wire, goes to bulb monitoring unit, and clock) to also find 0.8 amp current. Installed both the above fuses = 1.6 amps current. That "sort of" makes sense I thought, because that's a substantial current and when I installed the new battery there was a nice spark at the terminal which I thought strange but figured some capacitance somewhere was charging up. None of the other fuses, installed alone, resulted in any current. Scratching my head and looking at the engine and frame wiring diagrams I could not figure any common load-drawing relay or device between these two fuses/circuits. So I resorted to direct exam and exposed and checked every connector. No bare wires, no cracked insulation. There sure is a mess of wiring and connectors packed and cooking under the tank, though, not my idea of good design really. Note the above readings were obtained both with and without the instrument cluster installed. I took the amp-meter out of the circuit, reconnected the battery, and turned the ignition switch (key) on and off a few times and leaving it on felt each relay for any heat. None. Said "Well I'll be dammed" and I've monitored battery voltage for over 16 hours now and it's 12.90 volts and holding. There is no more drain with the ignition off. I'm happy, but would rather have found a source of the problem. Thanks all for your thoughtful and helpful input. Ride safe.

    

Adiwan Djohanli

Adiwan Djohanli
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Problem "solved"?

Next time it happens again..please measure the current of the 2 fuses, but this time take out the ECU ?Motronic. See if there is still current.

Good luck.


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Adiwan Djohanli
Jakarta-Indonesia[i]
    

Simon

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Banjak terima kasih, Adiwan.
I did not mention in my post but I got the same results with both the Motronic and the ABS "brains" disconnected, and just for good measure with the instruments disconnected also. I find it so strange that the current draw was equally 0.8 amps on each of those two unrelated circuits. The only thing which comes to mind is the heated grips, having a resistance of 7-8 ohms (each). That would be a current of 12/7.5 = 1.6 amps... Still a mystery, as all the wiring looks good.
Thanks again for the helpful suggestions.

    

charlie99

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just a guess simon ....the only thing that you said that you did was to excersize the main switch.

it might be a good idea to get some contact cleaner and deoxit and attempt to open it up and/or clean it out ...i have seen bits of brass/copper sit between "tracks" on switches before .


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
1987 k100rs ########   "Red"  - (red sports rs TWB style )
1989 K100rt #009637   "Black Betty"  (naked rt ala Nigel , now sporting an rs main fairing )
    

Adiwan Djohanli

Adiwan Djohanli
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Simon...

Where did you learn the language: Banyak terima kasih (thank you very much)

You are far away from this part of the world.

Cheers.


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Adiwan Djohanli
Jakarta-Indonesia[i]
    

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