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Jimi's Got a Glitch (brake/tail fail indicator light)

Discussion in 'The Garage' started by YamadudeXS650C, Aug 19, 2019.

  1. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    Jimi has been real good to me since I found him for sale on the side of the road two years ago for $500 just east of Richfield Springs. He has served as my winter rat, though I keep him well-maintained.

    1980 XS650G Special, essentially stock, electrical system unmolested. 6,000 miles on the odo. Some might remember him from local winter trips I've taken.

    Jimi.smaller.jpg

    So, last week we were in the Catskill mountains and the red brake/tail fail light comes flickering on briefly during upshifts. Came to a halt, turned the bike off. Switch on, and the light comes on constant. Start the bike, the light goes off. Take off down the road, and it again flickers on briefly during upshifts. No other anomalies .

    brake light 003.JPG

    The lights all work fine.
    Once we were home, I read the other postings about this same issue, so I did the following:

    > Tried 2 other 1157 bulbs, and even hooked up a spare complete tail lamp assembly to the connections under the seat. No improvement.

    I have read that this brake/tail fail light also serves as an alternator status indicator, so I did these diagnostics:

    > Battery is good. 12.6v as it sits. Starts the bike easily, quickly.
    > Load test: With volt meter connected, I started the bike: volts drop to 10.5 while the starter is engaged (WNL)
    > Idling, I'm getting 12.6V
    > At 3,000rpm, I've got 14.7 V
    > out on the road, I'm getting 14.8 V at 3,000 and 4,000 rpm, with no voltage peculiarities as I go through the gears, nor when the red light flickers on.

    Ive looked inside the headlight bucket and don't see any bad connections.

    I put a temporary jumper wire from the battery ground to the taillamp ground wire to make sure I'm getting a solid ground.

    So, I'm stumped at this point. Any ideas?
    .
    .
     
    Last edited: Aug 19, 2019
    Jim likes this.
  2. Jim

    Jim People will come Ray, people will definately come. Top Contributor XS650.com Supporter

    If the brake and tail lights are working normally, about all it could be is the "Light Checker." My book doesn't show it clearly, but it looks like it's just underneath the RLU.
     
    gggGary and YamadudeXS650C like this.
  3. 5twins

    5twins XS650 Guru Top Contributor

    17,776
    7,584
    688
    Maybe the light checker unit is going bad? I've not heard of this being an issue but anything is possible on bikes this old. I don't think there's anything you can do to it as far as servicing goes because it's sealed up in rubber. Maybe check the plug and wire connections?
     
    gggGary and YamadudeXS650C like this.
  4. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    I'm trying to identify the Light Checker......not sure I've found it yet.
    By RLU, do you mean the Reserve Lighting Device, Jim?
     
    Jim likes this.
  5. Jim

    Jim People will come Ray, people will definately come. Top Contributor XS650.com Supporter

    Yeah. According to my Yamaha book, the SG just has the RLU... and the G has both the RLU and Light Checker.

    IMG_20190819_130217.jpg
     
    gggGary and YamadudeXS650C like this.
  6. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    Yup, I've got that indicated on my wiring diagrams, too, but finding it on the bike is more difficult.
    ....and altho I've got the Yamaha, Clymer and Haynes manuals, they don't picture it or otherwise diagram it.
     
    gggGary and Jim like this.
  7. Jim

    Jim People will come Ray, people will definately come. Top Contributor XS650.com Supporter

    Here's the only ref. I could find.... Looks to be underneath the RLU.

    IMG_20190819_131937.jpg

    IMG_20190819_131946.jpg
     
    gggGary and YamadudeXS650C like this.
  8. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    Thanks, Jim !
    Aha! ...buried deep in the box, underneath sheet metal, and out of plain sight, it seems. When I lift the RLU, it is not revealed.
    I will look further and perhaps the connector is accessable..
     
    Jim, MaxPete and gggGary like this.
  9. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    The Mystery continues.....it is not below the RLU. The tool box fills that cavity.
     
    Jim and MaxPete like this.
  10. MaxPete

    MaxPete Life with Lucille...I suggest, she decides. Top Contributor XS650.com Supporter

    Maybe you've got a bad connector up in the headlight bucket or under the fuel tank Dude...?
     
    YamadudeXS650C likes this.
  11. 5twins

    5twins XS650 Guru Top Contributor

    17,776
    7,584
    688
    Yes, it's buried behind the battery box but in front of the rear inner fender. The connector should be up on top of the battery box though. To get at the unit, that rear inner fender needs to come off. You can see it here, it's the little black rubber box hanging off the bottom of the tool box .....

    [​IMG]
     
    MaxPete, YamadudeXS650C and Jim like this.
  12. XSLeo

    XSLeo XS650 Guru Top Contributor

    One way to ID electrical parts is by the wiring. Everything has a different combo of the wires color and number of wires.
    Look on your wiring diagram. Find the unit you are looking for. In this case the light checker. You will see it has 7 wires.
    Colors are black, yellow, red/white, black/red, blue, blue/yellow and brown.
    You might have to look in from the side to see it. I think its mounted on the front of the rear fender, or on the back of the battery box. Not sure.
    Leo
     
    YamadudeXS650C likes this.
  13. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    AHA !
    Thanks, 5T.
    I'm back to my search for the connector.
     
  14. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    Yup, that's part of my search. Its amazing how intact these connections are on this bike.
     
  15. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    Yes, the connector is right there in plain sight :doh:
    I cleaned it when I got the bike, and just did so, again. No help:(
    ..
     
  16. Jim

    Jim People will come Ray, people will definately come. Top Contributor XS650.com Supporter

    Although I'm sure someone knows how to jumper around it, but since both your rear lights work normally, you could just pull the little peanut bulb and call it a day.
     
    MaxPete likes this.
  17. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    :)I had that thought. But was hoping someone else would suggest it first.
     
    Jim likes this.
  18. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    .....or a piece of black tape.
     
    Jim likes this.
  19. Jim

    Jim People will come Ray, people will definately come. Top Contributor XS650.com Supporter

    Lookie what I just found in my XS boneyard Jeff. I have no idea if it works or not. Yours for shipping if you want it.

    IMG_20190819_144125.jpg
     
    YamadudeXS650C likes this.
  20. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    Absolutley, Jim !!
    Thank You !
    I'll try it, then find a spot for it if it works.
    I'll PM you.
     

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