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Discussion in 'The Garage' started by Raymondo, Jun 13, 2019.

  1. 5twins

    5twins XS650 Guru Top Contributor

    Yes, that small rubber box you found behind the battery with the 7 wires sounds like the light checker. Two versions were used on these. The Standard model used a simpler 3 wire unit. It monitored just the brake light and is easy to eliminate - you just unplug and remove it. Your Special model got the more complicated 7 wire unit. It monitors both the tail light and the brake light. Power for the tail light passes through it so you can't just remove it without adding a jumper wire to restore the power path to the tail light. Both units trigger a warning light in your dash if the brake light on the Standard or the brake or tail light on the Special burn out. Mine's gone, along with my reserve lighting unit.

    I actually had no problem with the light checker but when I switched to an L.E.D. tail light bulb, the warning light in the dash came on full time. I guess the low voltage use of the L.E.D. fooled the unit into thinking the bulb was burned out, so I removed it.
  2. Raymondo

    Raymondo XS650 owner, fettler, setting out on a journey

    Jim, thanks for the pointer - I have printed off the first one which will provide a useful reference & check.

    5T, thanks for identifying the lights checker. I know it works - the first time I ran the engine, just for a few minutes back in June, the bike was part dismantled and was using a fuel bottle hanging from a rafter in the garage. This bright red light in the middle of the warning cluster immediately came on and got my full attention because that's where you might reasonably expect an oil pressure warning. Glasses on and close scrutiny showed it was just a lights warning - was I relieved?

    In fact, at that point it was quite funny 'coz the rear mudguard and tail light were sitting on the bench . . .
  3. MaxPete

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

    It is interesting how Yamaha put all this fancy technology into systems to alert us to the failure of a bulb....I don’t think any other bike or car maker did that.

    Sort of technological dead end / solution looking for a problem I guess.
  4. Raymondo

    Raymondo XS650 owner, fettler, setting out on a journey

    Gives a bit of scope for pruning the number of wires running around though . . .

    Today, I have mostly been in the garage playing with coloured pens:


    Before you can hop, Grasshopper, you must find out what's there.

    I suppose it's fun in a way?
    MaxPete, Jim, Brassneck and 2 others like this.
  5. 5twins

    5twins XS650 Guru Top Contributor

    You'll need to keep up the research. That drawing you made shows some discrepancies. There is no dark blue wire going into the left control. There's a dark green for the right signal, and a normal green for the low beam. Maybe you confused one of those for a dark blue? I think the yellow/black soldered to yellows is normal but that yellow running to the headlight plug shouldn't connect to black, that's the ground. it should go to yellow (high beam). The end that goes nowhere originally went to the reserve lighting unit. The blue/yellow also originally came from the reserve lighting unit. It was the power feed to the hi/lo switch so will now need to be tied into the headlight on/off switch somehow. Normally, when you removed the RLU, you jumpered it to the blue/black to accomplish this.
    MaxPete and Raymondo like this.
  6. Raymondo

    Raymondo XS650 owner, fettler, setting out on a journey

    5T - you couldn't pop round and give me a hand, could you?

    I'm certain there will be discrepancies - at the moment, I'm just faithfully recording what is there.

    For the left handlebar, I have found 11 wires - 6 go to a block connector and 5 are loose wires. The block of six has Pink (horn), Brown/White (flasher relay), Yellow/Red (flasher cancel), Yellow/Black (joins up with yellow to headlamp, tacho and nowhere), Dark Blue (goes nowhere - I think it's blue), Blue/Yellow (what I thought was indicator harness, but might have been reserve lighting unit). The single loose wires are Yellow (headlamp), Green (headlamp), Black (headlamp), Brown (l/h indicator), Green/Black (r/h indicator).

    Some of the colours are a bit hard to call. There's Brown, Dark Brown and Chocolate, as well as Black/Brown and to add to the confusion, some PO has added lots of a different shade of brown. Plus some of the older wires are faded and dirty, so its hard to discern Red/White from Red/Yellow. The Sky Blue looks like duck-egg green in some places and has faded to almost cream in others.

    There's quite a few which don't go anywhere. Often terminated with a wrap of insulating tape.

    Some of the 41 year old cabling is very brittle and faded.

    Many other wires are newer, but often these have messy soldered joints with 5 or 6 black or brown cables wound together and soldered over. I suppose these are intended to be earth (ground) wires?

    I'm hoping that as this task continues it will become clearer. Already feels as though there will be scope to reduce the complexity.

    Onwards and (slowly) upwards.
    MaxPete and Jim like this.
  7. 5twins

    5twins XS650 Guru Top Contributor

    The black ground wire coming out of the left switch assembly is the ground for the whole thing. Don't connect it to the headlight ground, connect it to one of the ground wires that come out of the two harness looms. The headlight ground wire also gets connected to one of those. If you connected the switch ground to the headlight ground, you will have connected together two wires that are seeking a ground. Neither has it on their own and they're not going to find it connected to each other.
    Raymondo and MaxPete like this.
  8. Raymondo

    Raymondo XS650 owner, fettler, setting out on a journey

    5T, thank you for this!

    I followed the link you gave earlier for reserve lighting unit, so now I know what that is. Your dip element fails so the bike automatically switches to main bean AND illuminates a warning light to explain why the oncoming 40-ton lorry just lit up his eighteen headlamps and spots to full beam. Hahaha - absolute genius!

    The earth wires are very poor and definitely need re-doing. Things have moved on a bit since yesterday:



    Been doing some dissecting. That sound better than pulling it all apart wire by wire to see where it all goes.

    As noted above, the wiring is old, hacked about and of variable quality. Perhaps looks like I'm committed to fully replacing it now?

    Just hope I don't regret this . . .
    Last edited: Sep 12, 2019 at 11:21 AM
    MaxPete and Jim like this.

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