Blowing headlight fuse

[aldo5468]

My nearly stock '82 Special is blowing headlight fuses and so far, I haven't been able to figure out why. All headlight wiring is stock; still have the RLU - saw no visible wiring damage when I removed it for inspection, and the connector seems to close tightly; no visible cuts/breaks in insulation on the headlight wiring inside the headlight bucket; all three grommets in headlight bucket holes are in good shape; fuse block is good (I rebuilt it two years ago using the Radio Shack method); headlamp has appropriate resistance readings between the ground lug and the high and low beam lugs, so is not shorted internally; headlamp plug is not shorted internally (no continuity wire-to-wire when removed from harness). With the ignition key either off or on and the beam selector switch on "Low", I have continuity between the ground lead in the headlamp plug and the yellow wire. With the beam selector switch on "High", I have continuity between the ground lead and both the yellow and green wires. I took the left side handlebar switch apart - none of the headlight-involved wires are loose from their solder points and there are no visible insulation breaks. Turn signals work fine. Subject search on the forum didn't turn up anything helpful. Any ideas would be greatly appreciated - thanx in advance.

 

[jayel]

My nearly stock '82 Special is blowing headlight fuses and so far, I haven't been able to figure out why. With the ignition key either off or on and the beam selector switch on "Low", I have continuity between the ground lead in the headlamp plug and the yellow wire. With the beam selector switch on "High", I have continuity between the ground lead and both the yellow and green wires. I took the left side handlebar switch apart - none of the headlight-involved wires are loose from their solder points and there are no visible insulation breaks. Turn signals work fine. Subject search on the forum didn't turn up anything helpful. Any ideas would be greatly appreciated - thanx in advance.

high beam is the yellow wire, low is the green but you are not looking for continuity you should be testing for voltage... 12v on yellow or green, one or the other but not both at the same time if you have voltage on both at the same time you've just doubled the draw check the switch wires from bar into headkight

 

[5twins]

Maybe your RLU has gone bad. It's supposed to switch from low to high beam if the low burns out but maybe yours is stuck somewhere in between, powering both. Simple enough to try, just unplug it and jumper the required wire .....

http://www.excess650.co.uk/tips & tricks.htm

 

[aldo5468]

Maybe your RLU has gone bad. It's supposed to switch from low to high beam if the low burns out but maybe yours is stuck somewhere in between, powering both. Simple enough to try, just unplug it and jumper the required wire .....

http://www.excess650.co.uk/tips & tricks.htm

Good call, 5twins - it was the RLU. I had begun to suspect it, simply because I couldn't find any other visible fault in plug connections, wire insulation, headlight switch, etc. I made up a small jumper to connect the pins for the blue-yellow and blue-black wires and threw the RLU in the trashcan. Problem solved - many thanks.

 

[5twins]

Now, put that "Headlight Failure" indicator light to good use since you no longer need it .....

http://xs650temp.proboards.com/index.cgi?board=Charging&action=display&thread=9140

 

[aldo5468]

That certainly is a much more valuable use for "white" light. However, I don't have one anymore - last year, I removed the pilot light box, installed an SR500 tach to regain the neutral and Turn Signal pilots, and mounted a voltmeter between the speedo and tach.