no lights after R&R upgrade

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  • crookedspoon
    • Jan 2026

    #1

    no lights after R&R upgrade

    hi all,

    so I installed a SH775 R&R on my old GS1000 '78 — it still had a separate regulator and rectifier and the cable mess that goes with it.
    Installation went fine, have a solid 14V on the battery when idling, engine seems to be running smoother at low revs as well because of stronger sparks.

    Only now, the lights aren't working anymore. No headlight, no high-beam, no taillight and no instrument lights. Brake light is fine, blinkers are fine.


    These cables are left unused now -> the stator-cables used to go in here. The single green/white cable, I think, is the one that did the headlight loop. I'm unsure how much the POs have improvised with the electrics.

    Any advise how to troubleshoot this? I have the electric schematics studied, but I'm not sure where to start really. Would appreciate any tips on where to start troubleshooting!

    thanks!
    Last edited by Guest; 07-12-2016, 06:25 AM.
  • tom203
    Forum Guru
    Past Site Supporter
    • Aug 2010
    • 8925
    • Norway,Maine

    #2
    Check for power at headlight fuse- should power "on" with ignition switch. Swap fuse with another 10 amp one in case it's fooling you.
    1981 gs650L

    "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

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    • crookedspoon

      #3
      oh, right: thanks for the feedback. Forgot to mention that I checked the fuse. It gets power and the fuse is working!

      Comment

      • tom203
        Forum Guru
        Past Site Supporter
        • Aug 2010
        • 8925
        • Norway,Maine

        #4
        Anything happen when you turn headlight switch " on/off" ?
        1981 gs650L

        "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

        Comment

        • crookedspoon

          #5
          nope... light stays off, whether switch is on 'on' or 'off', high or low beam. No fuses are blowing either.
          High-beam headlight flashing doesn't do anything either...

          Comment

          • tom203
            Forum Guru
            Past Site Supporter
            • Aug 2010
            • 8925
            • Norway,Maine

            #6
            Is your wiring layout similar to this 79 gs850?

            1981 gs650L

            "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

            Comment

            • Cipher
              Forum Sage
              • Mar 2016
              • 3129
              • Toronto Ontario

              #7
              I am no electrical guru but the headlight bypass thing may be the cause of this. It sounds like you have cut the circuit to the headlamp.
              1983 GS 550 LD
              2009 BMW K1300s

              Comment

              • crookedspoon

                #8
                I think I'm an idiot... will have to check again later when it stops raining ? a cable to the fusebox (fuse for the lights) got disconnected while fiddling around.

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