K11 Owners Group

Scott_Anderson · Posted: Thu Aug 08, 2019 6:16 pm Post subject:

Yep, it's called a "BMU" for bulb monitor unit.....
It is supposed to, as the name implies, monitor the brake lamp and light the red warning dash light if the brake lamp fails, or if either of the brake lever switches fail(startup test).

BTW, the BMU does not play well with LED lamps... Drake has written up a procedure to alter or bypass the BMU unit if you use an LED brake lamp.
_________________
Ride safe.

1995 K1100LT 0302044
1997 R1100RT ZC62149
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
Garmin Zumo 550
Garmin Zumo XT
"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)

Jim · Posted: Fri Aug 09, 2019 12:03 am Post subject:

Make sure you have a good German bulb in the brake light socket. I couldn't get Asian bulbs to work on the K. The bulbs were OK - the BMU didn't like them.
_________________
Jim
1997 K1100LTSE 94,000 - has gremlins!
1995 R100RT Classic 16,650 crashed - repairing
1992 K75RTP 46,000

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

flybd5 · Posted: Fri Aug 09, 2019 2:09 am Post subject:

I'm not getting any warnings on the dash. And German bulbs? Smile

I think one of the two connectors related to this have become disconnected.
_________________
To err once is human. To do so repeatedly is incompetence.
1995 K1100LT SE

flybd5 · Posted: Fri Aug 09, 2019 2:27 pm Post subject:

The mechanic figured it out. The rear brake pedal activates the brake light just fine. It's the hand brake that doesn't work, and it makes sense, because that's part of where the bike landed when I dropped it, and the brake mechanism went south too, leaking fluid. He will replace it.
_________________
To err once is human. To do so repeatedly is incompetence.
1995 K1100LT SE

Flying Duck · Posted: Sat Aug 10, 2019 2:41 pm Post subject:

The BMU:

http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/bmu/bmu.htm
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

flybd5 · Posted: Mon Aug 12, 2019 4:24 am Post subject:

Flying Duck · Posted: Mon Aug 12, 2019 1:32 pm Post subject:

Welded with ultrasoujnd? Nah, There's just some expoxy or whatever. Just stick a screwdriver in around the edges and pop it open.

And in case you want to run LED turn signal bulbs you might want to do this while you have it apart:
http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/ledoemflrelay/ledoemflrelay.htm
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

flybd5 · Posted: Tue Aug 13, 2019 4:35 am Post subject:

flybd5 · Posted: Tue Aug 13, 2019 4:19 pm Post subject:

I got it open. The casing is in fact ultrasound welded, rather than gluing the two molded halves together. You were right, the bottom where the connector comes out just had this simple glue. The housing on the connector popped off and I pulled out the board.

The pcb appears to be the same, but with different identifying stencil on the side with the transformer coils. This one has a symbol, then 4D, and below that 754093-A. The most significant difference is the absence of a number of components that are there on the picture on that link you posted. On the front the capacitor at top right is gone, on the back a whole row of what appear to be resistors is gone, among other things.

There's no apparent damage. Would be nice to have a schematic to troubleshoot it. I'll post pics tomorrow.
_________________
To err once is human. To do so repeatedly is incompetence.
1995 K1100LT SE

flybd5 · Posted: Wed Aug 14, 2019 4:19 am Post subject:

_________________
To err once is human. To do so repeatedly is incompetence.
1995 K1100LT SE