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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: henbird57 on March 09, 2025, 07:50:02 PM

Title: Never A Bulb Warning Light
Post by: henbird57 on March 09, 2025, 07:50:02 PM
1993 K1100RS -I never have noticed a bulb warning light on the speedometer even when my headlight connector was separated from the bulb.  There isn't even the logo in the lower right corner of the speedometer that I have seen on other models(K100).  Previous owner has added after market pulsing brake lights. It has been this way since I bought it in 2012.  Recently the fuse for tail light will blow when immediately starting the bike.  Suspecting he did something with the BMU as I have seen suggested on this site in previous posts.  Is this where I should begin?
Title: Re: Never A Bulb Warning Light
Post by: frankenduck on March 09, 2025, 09:58:14 PM
BMU has nothing to do with the headlight. It only monitors the tail and brake light bulbs as well as the brake switches.

Learn more here:
https://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/bmu/bmu.htm

It's not common but it is possible that the insulation from the BMU to the taillight has worn and is grounding to the frame.

First thing I would do is pull the BMU and see if the gray/black wire shorts to ground.
Title: Re: Never A Bulb Warning Light
Post by: henbird57 on March 10, 2025, 04:23:17 PM
Thanks frankenduck, I will let you know how it all worked out.
Title: Re: Never A Bulb Warning Light
Post by: henbird57 on March 14, 2025, 09:25:17 PM
Your diagnosis was correct Frankenduck.  Ran another wire to replace, all good now. Thank you.  Collie pup and a collie flower for you!
Title: Re: Never A Bulb Warning Light
Post by: frankenduck on March 14, 2025, 11:56:17 PM
Glad that my Internet diagnosis worked for you.

(That Collie-flower poem is a dad joke that I had to endure WAY too many times in my life. Almost daily.)