BMW K bikes (Bricks)

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Jonas Bodin

Jonas Bodin
active member
active member
Hello!

I'm changing the original cluster for an aftermarket "all in one"-speedometer.

My first question is if the lamp monitoring needs to be connected to anything? I don't feel the need of the luxury of lamp monitoring but of course want the bike to work properly  Cool

The second question is if the cancel relay signal (blue/green, no21) needs to be connected? I'm guessing it has something to do with the automatic cancelling of the turn signals? Doesn't feel the need of this luxury either, but again want's to know if it will affect the bike in any way to just leave it out?

Third and last I wonder if it's possible to use the speedometer illumination (grey/blue, no24) as a +12V source to indicate that the lights are on? I.e. will there be +12V on this cable when the lights are turned on? (And no feed when the lights are off?)

/Jonas

    

BobT

BobT
Life time member
Life time member
The Bulb monitoring unit can be completely bypassed, something that you need to do when you fit LED rear light bulbs. The diagram for doing it is on this forum somewhere as it has been covered many times. Mine has been eliminated and has been working fine for years now.

    

Jonas Bodin

Jonas Bodin
active member
active member
Lamp monitoring, cancel relay and speedometer illumination Img_0114

    

Holister

Holister
Life time member
Life time member
This may be simpler to follow.
Remove the BMU and insert jumper wires as per the diagram below. You'll just need some spade connectors from an auto or electronics store to crimp on the ends.
Don't throw the BMU away. Pass it on to someone in need or sell it on ebay.
Lamp monitoring, cancel relay and speedometer illumination Bmu11



Jonas Bodin wrote:Third and last I wonder if it's possible to use the speedometer illumination (grey/blue, no24) as a +12V source to indicate that the lights are on? I.e. will there be +12V on this cable when the lights are turned on? (And no feed when the lights are off?)
Yes. Instrument lights are switched off the main R/H light switch. In some parts of the world (like the US) this switch was later removed and lights remained on all the time. All later (16v ??) K-bikes were the same.
IMO tho... its very annoying to have a dash light glaring in your eyes constantly while you're riding at night and it can affect your vision of the road ahead. The instrument lights are just a dim glow. I would leave it out.


__________________________________________________

1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
 Lamp monitoring, cancel relay and speedometer illumination Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

Jonas Bodin

Jonas Bodin
active member
active member
Holister wrote:This may be simpler to follow.
Remove the BMU and insert jumper wires as per the diagram below. You'll just need some spade connectors from an auto or electronics store to crimp on the ends.
Don't throw the BMU away. Pass it on to someone in need or sell it on ebay.
Lamp monitoring, cancel relay and speedometer illumination Bmu11



Jonas Bodin wrote:Third and last I wonder if it's possible to use the speedometer illumination (grey/blue, no24) as a +12V source to indicate that the lights are on? I.e. will there be +12V on this cable when the lights are turned on? (And no feed when the lights are off?)
Yes. Instrument lights are switched off the main R/H light switch. In some parts of the world (like the US) this switch was later removed and lights remained on all the time. All later (16v ??) K-bikes were the same.
IMO tho... its very annoying to have a dash light glaring in your eyes constantly while you're riding at night and it can affect your vision of the road ahead. The instrument lights are just a dim glow. I would leave it out.

Thank's for your help!

Getting closer to sorting the Electrics out Smile

    

6Back to top Go down   Lamp monitoring, cancel relay and speedometer illumination Empty bmu eliminated still no brake lights Wed Dec 29, 2021 11:35 am

Spexbike

Spexbike
active member
active member
Hi there Peeps,
85 K100rs,I converted all my lights to led a while ago,modified the blinker relay and everything worked as it should.
The rear is an all in one brake/tail/license plate light.
I got new rear sets, including a new rear brake master cylinder with integrated reservoir and a pressure switch.
Before I switched to the new master cylinder and pressure switch the front and rear brake light worked fine,now neither brake light works.
- I tried 2 different pressure switches 
- All the blinkers,headlight and tail light work, but no break lights !
- I eliminated the bmu as described in this thread,thinking it would do the trick,but no.
- I do get current to the E2 grey/green wire/plug when rear brake is pressed.  
- I have continuity between the main ground under the tank and the ground at the gear box.
- cleaned the grounds anyways and put a bit of electro grease on contacts. 
- When I press the front or rear brake, the license plate light gets a tad bid brighter.
- wiggled the wires from tail light to the harness a bit,no difference.
Any advice before I set it on fire and push it off the next cliff? 
Much appreciate any good ideas,THX

http://www.spextattoo.com/
    

RicK G

RicK G
admin
admin
No need to post the same message in two places the same people see it when it comes up as a new post

Admin


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

Spexbike

Spexbike
active member
active member
RicK G wrote:No need to post the same message in two places the same people see it when it comes up as a new post

Admin
Sorry,just trying to get an answer,thx for the heads up

http://www.spextattoo.com/
    

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Sounds like a cafe racer, but okay, I'll bite.

Does the brake light work if you disconnect the rear brake pressure switch?  That would essentially put you back to where you were before you started having the problem.

If it does, then the problem is in the wiring of the rear brake pressure switch. 

If you still have a problem, you must have disturbed the wiring at your all -in-one brake-tail -license light unit.  Get the front brake switch working then go back and reconnect the rear switch to see if things work.

Not knowing what you did to remove the BMU, I'm at a disadvantage as to really understanding where you need to look for the problem.


__________________________________________________
Present:
1994 K75RT
1991 K100RS


Past:
1988 K100RS SE
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

10Back to top Go down   Lamp monitoring, cancel relay and speedometer illumination Empty Bmu Wed Dec 29, 2021 7:02 pm

daveyson

daveyson
Life time member
Life time member
Some other stuff to try. I'll guess you have a jumper wire from e1, e2 and 54a. I'd remove it and put a jumper wire from e2 to 54a (rear brake pedal to brake light) Then the light should work with the pedal pressed. Then remove it from e2 and place it in e1 (front brake to brake light) to see if that works. 

Since both front and rear don't work, and the license plate light gets brighter, I'm thinking about a bad earth. With a test light clip on battery positive and probe to brake light earth, the test light should glow. Then the other way around it should glow with a brake lever pressed.

If the globe is getting power and earth but not working, you want another globe.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

acftfliehr

acftfliehr
active member
active member
All, I like the idea of making Jumpers for this....  So simple and effectively clean without going through the act of with disruption at the connector level..

I started to look at both diagrams and compared the verbage of the original diagram with the present and it seems to have to be rotated to make sense side by side...

See if this is a better comparison with both....

http://forum.kforum-tech.com/members-upload/uploads/BMU_Bypass_w_Jumpers.pdf


http://forum.kforum-tech.com/members-upload/uploads/BMU_Bypass.pdf

    

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