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Thread: '92 K75S Engine Trouble Light Stays On - help!

  1. #1

    '92 K75S Engine Trouble Light Stays On - help!

    My 92 K75S sat for about 6 years after making a cross-country trip. I flew out to Calif and got the bike and rode it back to Ohio in 2010. The prior owner took the bike to Cal-BMW for new tires, battery, brake fluid, and general check out before I flew out. My good luck was having 98lee spend about 10 hours with me after I landed in Calif. He gave me a whirlwind tutorial on K75S bikes while checking out the whole bike. Bike ran great, but since I have a number of other bikes, the 92 K75S sat thereafter. (This didn't stop me from flying out to AZ last year and getting an 88 K75S to make another cross country trip - but I let Iron Horse BMW give that bike a thorough going over).

    So now I am giving my well rested 92 K75S (this is the blue one, Lee) a going over. I replaced tires, all fluids and filters (oil, air, fuel). All of the body work was removed in 2010 and replaced recently (what an interesting experience that was in some doing and undoing until I got it back together). The front brake lines were replaced (with Spiegler lines) and all brake fluid was flushed. Brakes feel good, not mushy.

    Today I added fuel and the bike started right up. Once rolling the ABS light cleared, but the red engine light (with triangle symbol) stayed on. In looking at the wiring diagram I don't see where I could have left something unplugged, but I did notice a "bulb monitor" function. I have replaced brake, tail light, and head light with LED bulbs and have added LED running lights. I also added a Stebel horn using the existing horn wires.

    Any suggestions regarding the Engine Trouble Light? Is this just a result of the "bulb monitor" not liking the LED lights? All connectors were disconnected, cleaned (WD-40), had a dab of dielectric grease applied, and reassembled - I did this one-at-a-time to avoid confusion - all lights (e.g. turn, hazard, brake, tail, headlight, etc.) appear to work correctly. Wonder if I have screwed something up?
    Last edited by robsryder; 07-10-2016 at 02:06 AM.

  2. #2
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    4,030
    Rob,

    There is no engine trouble light. That is the bulb monitor light. When you put in your led tail and brake lights the leds don't show the proper resistance to the bulb monitor, so you get the light. There are some leds that have a resistor in parallel with the led to trick the bulb monitor.

    As a test, change the tail and brake lights back to stock bulbs and make sure it works properly. Then search out leds that have the appropriate resistor.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  3. #3
    Thanks, Lee! Puts my mind at rest that it actually is something that I likely caused and can fix.

    As I've gone thru this bike, I've really come to appreciate the time and work that you did for me (and the K tutorial)!!

  4. #4
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    4,030
    Any time. If you are searching for another one, there happens to be several very nice ones for sale near me at the moment.


    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

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