Karranir Posted September 19, 2010 Share Posted September 19, 2010 I just wired a set of LED tail lights to my 78 XS400E. Just removed the old tail light and spliced in the wires for the tail where there used to be 3 wires meeting. Not a problem with the key on and the engine off. Works as a running light, lights up bright with the brakes applied. And then I go to start the bike. Starter clicks, the bike dies completely. I go to unscrew the negative terminal on the battery and the moment the screwdriver hits it, there's power again. Any ideas...? Link to comment Share on other sites More sharing options...
OllieB Posted September 19, 2010 Share Posted September 19, 2010 I just wired a set of LED tail lights to my 78 XS400E. Just removed the old tail light and spliced in the wires for the tail where there used to be 3 wires meeting. Not a problem with the key on and the engine off. Works as a running light, lights up bright with the brakes applied. And then I go to start the bike. Starter clicks, the bike dies completely. I go to unscrew the negative terminal on the battery and the moment the screwdriver hits it, there's power again. Any ideas...? On something like that, without being there it is hard to say. Could it be your battery is failing? You say there is juice the minute you touch the battery terminal - could the terminal be loose inside the battery and not making contact internally until some force is applied to the terminal? Had a battery do that once. Is the battery new or old and is it fully charged by an external charger, not the system on the bike? All this assuming your wiring job is correct and the light units are compatible and not defective. Link to comment Share on other sites More sharing options...
Karranir Posted September 19, 2010 Author Share Posted September 19, 2010 On something like that, without being there it is hard to say. Could it be your battery is failing? You say there is juice the minute you touch the battery terminal - could the terminal be loose inside the battery and not making contact internally until some force is applied to the terminal? Had a battery do that once. Is the battery new or old and is it fully charged by an external charger, not the system on the bike? All this assuming your wiring job is correct and the light units are compatible and not defective. I fully charged the battery with an external charger and tightened down the terminal, and now everything is fine. Bike starts with the lights on no problem. I guess I should really take some steel wool to all the ground connections just to be sure. I was gonna take it out for an hour or so and hope it doesn't decide to die on me. I'm sure the light unit is compatible, it's made for CB750s () and I'm pretty sure my wiring job is correct. I mean, I used crimp-on terminals and everything is nice and heat shrunk, so there's no short there, I'm positive of it. Can anyone think of anything else that might have caused the problem that I could try to correct? Kinda scares me that it works now haha. Anyone have any suggestions on a side mount license plate bracket? I really want to eliminate the rear fender entirely, now that I have the light mounted to the back of the seat. I have the current bracket flipped upside-down so it doesn't interfere with the tail light and it looks like absolute shit. Link to comment Share on other sites More sharing options...
rXsOwNeR Posted September 19, 2010 Share Posted September 19, 2010 I would de wire it and then re wire it one at a time to see where the fault lies , Its definatley shorting somewhere although why its coming back to life when you touch the neg terminal is beyond me . Thats a weird one for sure. Link to comment Share on other sites More sharing options...
OllieB Posted September 19, 2010 Share Posted September 19, 2010 I fully charged the battery with an external charger and tightened down the terminal, and now everything is fine. Bike starts with the lights on no problem. I guess I should really take some steel wool to all the ground connections just to be sure. I was gonna take it out for an hour or so and hope it doesn't decide to die on me. I'm sure the light unit is compatible, it's made for CB750s () and I'm pretty sure my wiring job is correct. I mean, I used crimp-on terminals and everything is nice and heat shrunk, so there's no short there, I'm positive of it. Can anyone think of anything else that might have caused the problem that I could try to correct? Kinda scares me that it works now haha. Anyone have any suggestions on a side mount license plate bracket? I really want to eliminate the rear fender entirely, now that I have the light mounted to the back of the seat. I have the current bracket flipped upside-down so it doesn't interfere with the tail light and it looks like absolute shit. Sounds like your problem was a loose and/or corroded terminal/connection. Only questioned the light compatibility and wiring because you didn't include much info. Yes, it would be good to go over the grounds on a bike as old as ours. Good luck on your ride. Link to comment Share on other sites More sharing options...
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