K11 Owners Group

pbciii · Posted: Sun Sep 14, 2014 8:10 pm Post subject: BMU Light

I've been having issues with my BMU light randomly coming on. Tried new bulbs - same result. I decided to remove the BMU relay and I think I followed the directions on ClassicBikes. BUT, it is still lit . . . did I miss something or can something else light the Triangle. 93 K1100LT

Inge K. · Posted: Mon Sep 15, 2014 12:21 am Post subject:

It could be that the wire (white/blue) between the instrument cluster and BMU relay socket or the ABS ECU is randomly shorting to ground.

Jim · Posted: Mon Sep 15, 2014 8:57 am Post subject:

Did you try using bulbs made in the Fatherland? I never had much luck with other bulbs - would not work, brand new out of the package. A lot of them apparently don't have the right type of filament. I always use German made - no problem.
_________________
Jim
1997 K1100LTSE 94,000 - still has gremlins!
1995 R100RT Classic 16,650 crashed - repaired!
1992 K75RTP 46,000

"We shall not all die, but we shall all be changed."

pbciii · Posted: Mon Sep 15, 2014 11:09 am Post subject:

I've tried the original German bulbs and "other" bulbs. Since I've removed the BMU, I think the brand should be moot. I'm not an expert at wiring diagrams but it looks like the only other thing "feeding" that bulb is the ABS brain. I'll try separating the two white/blue wires and see if that kills the light. I know it wouldn't flash at startup but the ABS light would still be active.

Is there any reason the ABS brain would be keeping that bulb on while stopping the flashing on that bulb and the ABS light? I don't want to disconnect the BMU light if the ABS brain is trying to tell me something! Any thoughts???

Shoganai · Posted: Wed Sep 24, 2014 10:02 am Post subject:

pbciii · Posted: Wed Sep 24, 2014 12:13 pm Post subject:

I searched the forum again and found a user that had this identical problem in 2013 and found the ABS brain was at fault. I've serviced the ABS switch, checked for fault codes again (found none), and finally contacted the ABS brain rebuilder in Japan. He's had me run some tests and wants me to check the wh/blue wire from the ABS brain (terminal eight) to the front display to insure it's not broken or shorted before sending it in for repair. Since I've removed the BMU relay, it should be a straight shot to the bulb. I opened the ABS brain and it's clean and dry with no signs of ever being wet. The mystery continues!!
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1993 K1100LT Classic Metallic Black

1Snowbum · Posted: Mon Oct 06, 2014 7:52 pm Post subject:

Before you assume the ABS brain is at fault, be aware that the BMU can have problems with ITS solder joints. While I can post some links to how to properly test the ABS, try checking the BMU. While the following article (well, the longish item #2 in the article) was written for problems I had with my BMU on my sidecar rig, which has extra lamps, a lot is applicable to the BMU's in general, and there are TWO types, with the exact SAME part numbers on them!
see, item 2, in the following:
http://bmwmotorcycletech.info/k-hints.htm

snowbum
_________________
Bob Fleischer, AKA Snowbum
dba Fleischer's Service,
http://bmwmotorcycletech.info

pbciii · Posted: Mon Oct 06, 2014 8:19 pm Post subject: Fixed

As I posted earlier I had already removed my BMU to facilitate LED brake lights. I started getting a steady BMU light after the ABS flashing stopped when rolling off. The only thing feeding the BMU light at this point was the ABS. If I unplugged the ABS, no BMU light - solid ABS light and no ABS!

So, I purchased a rebuilt ABS brain from Tosi in Japan. Problem instantly solved. Old brain had no fault codes but something was bad. I'm sending the old one to him to see if it's fixable. If so, he'll buy it for 8,000 yen. Keeping my fingers crossed . . .
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1993 K1100LT Classic Metallic Black

1Snowbum · Posted: Mon Oct 06, 2014 8:55 pm Post subject:

My error, I thought it was another poster that said that...I just went back through the thread and saw it was you, originator.
sorry,
bum
_________________
Bob Fleischer, AKA Snowbum
dba Fleischer's Service,
http://bmwmotorcycletech.info

pbciii · Posted: Mon Oct 06, 2014 9:20 pm Post subject:

No worries. I'm thankful for all the info and suggestions here.
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1993 K1100LT Classic Metallic Black