1981 HD Sportster Electrical Problem?

Question

My headlight & tail light stopped working after riding the other day. The tail light only works when the brakes are applied. I replaced the battery & the headlight switch. When I turn the power on, the generator light dims & I hear a pop from under the seat then the gen light brightens but still no head or tail light. This usually happens in about 15-20 sec cycle. I'm thinking that the lighting circuit breaker may be the problem. Any thoughts & suggestions? Are circuit breakers known to go bad? Could it be a short?

Answer 1

You have a short in the headlight-tail-running light circuit.  Many years ago I traced down a similiar problem on my friend's 80' FLH.  The problem ended up being inside the headlamp shell.  A wire had rubbed against a threaded stud or nut, either the one that held the shell on or held the direction lights on (can't remember for sure which one).  There was a stud and wire on both sides and on one side, vibration had worn through the insulation.  I wrapped it good with electrical tape and then split a short piece of automotive vacuum hose and slipped over the spot.  It never again caused a problem.

Answer 2

didnt you just post this exact same question a little while ago ?