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    Headlight fuse keeps blowing

    Wondering what the main reasons a headlight fuse would consistently blow, just started happening last night
    Ian

    1982 GS650GLZ
    1982 XS650

    #2



    Here's my battery test, see what you guys think
    Ian

    1982 GS650GLZ
    1982 XS650

    Comment


      #3
      Originally posted by timebombprod View Post
      https://youtu.be/8jRDkd5_NTU


      Here's my battery test, see what you guys think
      im not sure what the specs are for the range on your bike but in my experience and overvotage condition results in blown bulbs or bulbs that visibly "flare" in brightness.

      thought this was a 450 is it a 650?

      yeah so looked it up
      do dload this manual its the hammer of the gods

      14-15.5 v @5000 rpm
      Last edited by Cipher; 01-15-2022, 07:59 PM.
      1983 GS 550 LD
      2009 BMW K1300s

      Comment


        #4
        its a 650, i have it in my signature area. i do have the correct voltage at 5k but for some reason at idle im charging at 14.44v

        is there any other reason other than a bad regulator for my fuse to keep blowing?
        Ian

        1982 GS650GLZ
        1982 XS650

        Comment


          #5
          Originally posted by timebombprod View Post
          its a 650, i have it in my signature area. i do have the correct voltage at 5k but for some reason at idle im charging at 14.44v

          is there any other reason other than a bad regulator for my fuse to keep blowing?
          I think all these GS bikes had a leg of the stator going to the headlight.
          Its a dull pita biz but chase the wiring harness for the circuit whose fuse is blowing.
          An accumulation of resistance in the circuit should also cause fuses to blow.
          Also all old bike harnesses can suffer from fatigue in the section that gets twisted sided to side at the steering head.

          If its popping as soon a the light is on then its a joyful happy dead short which should be easy to find.
          So something is most likely shorting. But at least you have a meter.
          1983 GS 550 LD
          2009 BMW K1300s

          Comment


            #6
            Originally posted by Cipher View Post
            I think all these GS bikes had a leg of the stator going to the headlight.
            Its a dull pita biz but chase the wiring harness for the circuit whose fuse is blowing.
            An accumulation of resistance in the circuit should also cause fuses to blow.
            Also all old bike harnesses can suffer from fatigue in the section that gets twisted sided to side at the steering head.

            If its popping as soon a the light is on then its a joyful happy dead short which should be easy to find.
            So something is most likely shorting. But at least you have a meter.
            I did the headlight loop delete I run a sh775a R/R now, it doesn't pop as soon as I replace it, I turned the ignition on, off, the key on and off, hit both turn signals and I also revved it to 5k and it didn't blow, it just happened some point during riding, I'm not sure why?

            I guess.ill just trace the circuit and see if I can find something obvious going on
            Ian

            1982 GS650GLZ
            1982 XS650

            Comment


              #7
              okay so just for a quick check and not actually tracing the circuit i put a new fuse in, turned the key on, ignition on, ignition off, did both turn signals, turned the highbeams on then back to normal ones, pressed the brake lever, steered the forks to both sides all the way and key off, turned it back on, i turned my speakers on and redid everything i just said, and nothing happened to the fuse.

              i know this is a quick check and not thorough but i think what ill do tomorrow is somehow set it up to where i can tell exactly when the headlight goes out and put another fuse in, do the same thing, and see if it happens again.
              Ian

              1982 GS650GLZ
              1982 XS650

              Comment


                #8
                Originally posted by timebombprod View Post
                okay so just for a quick check and not actually tracing the circuit i put a new fuse in, turned the key on, ignition on, ignition off, did both turn signals, turned the highbeams on then back to normal ones, pressed the brake lever, steered the forks to both sides all the way and key off, turned it back on, i turned my speakers on and redid everything i just said, and nothing happened to the fuse.

                i know this is a quick check and not thorough but i think what ill do tomorrow is somehow set it up to where i can tell exactly when the headlight goes out and put another fuse in, do the same thing, and see if it happens again.
                you may have pinched somnething in your stator leg deletion too
                also are these glass tubes or plastic blades?
                The older tubes have issues with the holders getting corroded
                the flat blades have probs if you buy el cheapo ones as they tend to be ill fitting and will melt your fuse box and or blow
                1983 GS 550 LD
                2009 BMW K1300s

                Comment


                  #9
                  Originally posted by Cipher View Post
                  you may have pinched somnething in your stator leg deletion too
                  also are these glass tubes or plastic blades?
                  The older tubes have issues with the holders getting corroded
                  the flat blades have probs if you buy el cheapo ones as they tend to be ill fitting and will melt your fuse box and or blow

                  i have the glass fuses, i did the headlight loop deletion almost 2 years ago now and that specific wire doesnt have any power going to it anymore, i will have to check at the headlight loom to make sure that the inch of wire that still gets power is not possibly touching something and shorting out.

                  the last fuse i put in the fusebox was a brand new one, and the one before was old and bit of corrosion, i could have 2 faulty fuses but the fact that one blew before those two replacements probably means that is not the case.

                  this is a brand new issue but im glad its this and not something major, i can still ride around no problem but just not at night lol.
                  Ian

                  1982 GS650GLZ
                  1982 XS650

                  Comment


                    #10
                    good news, i found what keeps causing it the fuse to blow, i just have to narrow it down to the exact wire or whatever it is to fix it.

                    i went for a ride seeing as its night time and i could see right when my headlight goes out, i went through the powerband making sure it wasnt anything to do with too much current getting through the system and nothing blew, i got home and i turned full lock to the right, all was well, i did full lock to the left and the headlight went out, i put another fuse in and did full lock to the left and it went out again, so its somthing to do with the harness or the wiring coming from the left hand module that controls the low/high beam.

                    might do it tonight but dont know forsure, ill have to pull out the wiring diagram and narrow down my searches to make sure i dont do more than necessary.

                    thanks cipher for the help
                    Ian

                    1982 GS650GLZ
                    1982 XS650

                    Comment


                      #11
                      Originally posted by timebombprod View Post
                      good news, i found what keeps causing it the fuse to blow, i just have to narrow it down to the exact wire or whatever it is to fix it.

                      i went for a ride seeing as its night time and i could see right when my headlight goes out, i went through the powerband making sure it wasnt anything to do with too much current getting through the system and nothing blew, i got home and i turned full lock to the right, all was well, i did full lock to the left and the headlight went out, i put another fuse in and did full lock to the left and it went out again, so its somthing to do with the harness or the wiring coming from the left hand module that controls the low/high beam.

                      might do it tonight but dont know forsure, ill have to pull out the wiring diagram and narrow down my searches to make sure i dont do more than necessary.

                      thanks cipher for the help
                      First place to check is the harness as it goes past the steering stem and under the tank. This is obviously a part that gets repeated bending and you would not be the first to find issues at that point.
                      97 R1100R
                      Previous
                      80 GS850G, 79 Z400B, 85 R100RT, 80 Z650D, 76 CB200

                      Comment


                        #12
                        I gotta ask, what exactly am I gonna be looking for in the harness? Damage to wires?

                        I noticed that the black and white wire goes to many many other things but I'm guessing that's my ground wire so it shouldn't be the issue? Not sure, I'm gonna keep inspecting and see what I can find and if there's anything noticable and I'll take a picture of it
                        Ian

                        1982 GS650GLZ
                        1982 XS650

                        Comment


                          #13
                          Originally posted by timebombprod View Post
                          I gotta ask, what exactly am I gonna be looking for in the harness? Damage to wires?

                          I noticed that the black and white wire goes to many many other things but I'm guessing that's my ground wire so it shouldn't be the issue? Not sure, I'm gonna keep inspecting and see what I can find and if there's anything noticable and I'll take a picture of it
                          take a peek in the headlight bucket to
                          1983 GS 550 LD
                          2009 BMW K1300s

                          Comment


                            #14
                            I found the issue, my headlight dimmer module wires were rubbing in my triple tree area and rubbed through the wiring and was grounding on the frame
                            Ian

                            1982 GS650GLZ
                            1982 XS650

                            Comment


                              #15
                              Thanks for posting your results. You may have just helped someone else. Good job.

                              edit: also please post your meter readings as compared to the readings before finding the problem.
                              Larry

                              '79 GS 1000E
                              '93 Honda ST 1100 SOLD-- now residing in Arizona.
                              '18 Triumph Tiger 800 (gone too soon)
                              '19 Triumph Tiger 800 Christmas 2018 to me from me.
                              '01 BMW R1100RL project purchased from a friend.

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