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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Jbuffalo on March 15, 2014, 03:25:08 PM

Title: Bmw K75s update Tail light problem
Post by: Jbuffalo on March 15, 2014, 03:25:08 PM

The bike is turning over nicely and I will start it as soon as I get  new gas; tank clean, new filter.    The tail light is not working.  I had to clean up the back wiring because of an old brake flasher wired in but the tail light never had power.  The license plate bulb does have power but I found a 6 volt bulb in the socket, the brake light has power when the brake is applied.    Is the tail light /brake light a dual bulb?  I have a single socket.  All connections and relays cleaned, new right hand switch, new battery.  thanks Jim

Title: Re: Bmw K75s update Tail light problem
Post by: Inge K. on March 15, 2014, 03:38:51 PM

The tail/license and brake light is two separate bulbs in the OEM wiring, 10W and 21W.

Title: Re: Bmw K75s update Tail light problem
Post by: Jbuffalo on March 15, 2014, 03:49:21 PM

Thank you.  I now see that I have stock tail light sockets, I was not sure. 

Title: Re: Bmw K75s update Tail light problem
Post by: Jbuffalo on March 15, 2014, 03:52:14 PM

I also see that they are single bulbs.  I do not have power to the tail light. thank Jim

Title: Re: Bmw K75s update Tail light problem
Post by: Jbuffalo on March 15, 2014, 03:58:37 PM

Also note the heated handgrip on the left side does not work. 

Title: Re: Bmw K75s update Tail light problem
Post by: Inge K. on March 15, 2014, 03:59:48 PM

Does your park light  above the headlight function? If not check fuse #2.

Title: Re: Bmw K75s update Tail light problem
Post by: Jbuffalo on March 15, 2014, 06:20:11 PM

Parking light works, high and low beam work. 

Title: Re: Bmw K75s update Tail light problem
Post by: Inge K. on March 15, 2014, 07:53:17 PM

Then I would guess that you have a problem with the BMU, which you find in the relay box, center, LHS.
Measure if you got power at the output to the tail bulb (grey/black wire).
But first you could check at both sides of the connector in the duck tail (same colour code).

The BMU can be bypassed, .....if it's where the problem is, and you don't get another one.

Title: Re: Bmw K75s update Tail light problem
Post by: Jbuffalo on March 15, 2014, 09:10:36 PM

I will check as suggested.  I was also thinking of the bulb monitoring relay.  I ordered a working used one to test.  thanks Jim

Title: Re: Bmw K75s update Tail light problem
Post by: Jbuffalo on March 16, 2014, 09:29:46 AM

Following the directions I traced all the tail light wiring, cleaned all contacts and replaced a bulb that looked good but did not work.  I now have brake and tail lights.  thank you Jim

Title: Re: Bmw K75s update Tail light problem
Post by: Inge K. on March 16, 2014, 11:33:00 AM

  :clap:

Title: Re: Bmw K75s update Tail light problem
Post by: Jbuffalo on March 16, 2014, 02:13:07 PM

All systems work and the bike starts and runs.  I am now bleeding the brakes-thanks Jim