I just bought an 01 Road King Classic and I noticed last night when I was riding that the headlight brightness was changing every once in a while Is this a sign of some electrical part going bad or what? The bike has 15,000 miles on it.

 

Is that dimming a gradual thing, or does it get dim and then bright?

If gradual, which is very hard to detect when the bulb is actually wearing out! And what I mean is since the bulb most likely is an incandesant or a hallogen it won't last forever it clouds up the inside of the glass and less light is emitted.

If you have had a sharp jolt to the bulb it could go rather quickly and then poof its gone. Those I have seen, and some times the actuall bulb bursts.

But if yours is changing intensity, up and down, what are the rest of the lights doing, are they also getting bright and dim?

This could be a battery being week, not taking charge. Or a regulator going out.


Need more info, whats up with the lights when the engine is on/ off/ at idle/ and with it up around 1800 or so rpm's, with high beam/ low beam/ and break lights on and off? Post the rusults...

 

It's not a gradual thing it gets dim then bright and continues, it doesn't do it fast it will change about every 2 minutes or so. I have noticed the passing lamps doing it to but I haven't paid any attention to the rest of the lights. I don't think its the battery because it starts up fine everytime.

 

Just got my 04 ultra out of the shop. It was doing the same thing only it was after it had time to get fully warmed up. It ended up being the regulator breaking down and causing charging problems.

 

Take a look at the voltage regulator harness where it goes under the bracket on the frame. You may find the wires are chafed bare and it is shorting out to the frame. A common problem with baggers.

 

If all else fails, take the head lamp assy out of the front of the fork and pull off the wiring electrical connection to the bulb. In bright light look at the back of the bulb insulating material between the three prongs contacts, for heat and arcing burnt into the dirt from road grime that collects from riding in rainy damp weather / roads. It will kind of look like the arc trails that you could see in the inside of a distributor cap between the spark plug wire contacts.

That is something I have just found on mine when doing a conversion to the HID H-D lamp assy. I got to thinking about your post and it could have some bearing? If you find the little arc looking trails on the back of the bulb insulating block between the terminals.

Clean contacts only and back of bulb terminal insulator with some electrical contact cleaner or Isopropal alchol. Do not get any finger prints on the bulb or cleaner on the bulb if for some reason you have removed an H-4 type bulb from the head lamp assy, if you did wear cotton gloves when touching the bulb glass to keep your finger oils off of the glass and causing it to burst/burn out. You shouldn't have to remove the bulb from the headlamp. Then get some Permatex Electrical Contact silicone and put on the contacts and the BACK of the contact insulator of the bulb and the contacts in the wiring harness. You can gob it, that stuff is not going to melt and has a super high temp capability. It will keep future moisture off the contacts and the back of the bulb. This is just a though, its worth looking.