tonight while riding my 04 ultra my lights dimmed and I noticed my volt meter went down to about 12v. Then after a few seconds the lights got bright and the volt meter went back up to about 15. It did this several times, any ideas on what might be wrong?

 

Might want to start with the battery connectors... Next do a drop test on the battery (most parts stores will do this for ya)... Good place to start checking...

 

Also, I have read that the voltage regulators in the '07 have been having issues. Check battery connections first, thentalk to the dealer about the regulator. IMO

 

Thanks, I have read about the regulator problems with the 07's, mine is a 04. I havent had this bike long and the battery for all I know is the org. Could it be the battery is just dying out and I dont have any other electrical problems? I have looked at several links on electrical checks and plan on doing those this morning, if I can beat the heat out in the garage... even my pool water is too hott!!!! I'm hoping it's just a battery issue, the bike has about 11k miles on it, and I just noticed this problem last night coming to work. Again I'm going to do all the checks mentioned in the other threads on here and see what I come up with... I'll let you know what I find.

 

H-D sent me a letter about the voltage regulator on my '06 Ultra so they must be having problems with that year too. Like the rest have said, I would check the battery connections and if they looked OK then(and only then)would Iconsider taking it to the dealer to have it looked at.

 

..dealer replaced voltage regulator on my 06 SGunder service bulletin..don't know if they had problems with earlier years.
Later

 

Well okay heres the poop on my problem. I owe finding this problem to a link someone posted that I found that took me to the "Harley Davidson Hangout" site. I checked my battery connections all were fine. I check the voltage on my battery with ignition off and it was 12.5 Not great but not bad. 12.9 is supposedly 100% charged. Then I started the bike and my voltage went to about 13.5 and when I reved it it went up to about 14.5 all good. I decided to go and check the regulator and the stator. I unplugged the regulator connector going to the stator, (thru the crankcase) and with the igniton off I checked the end of the plug going back to the regulator, what I found was I had 12 volts on each pin to ground. Ahhh not good!!!!! Should have been less than 2 volts, and I checked my other bike and it was in fact less than .5 volt. Funny thing was when I checked it with a test light the light didn't come on like there was no voltage present, but when i checked with a digital meter it showed 12 volts. Don't even ask me why the test light didn't show up, could have been the resistance from the bulb in the test light messing with the dioed in the regulator (just a guess tho) Anyway, I called the dealer told them what I had found and they said yes, if I had more than 2 volts from either of those pins, what was happning was the diodes were faulty and it was allowing voltage from the battery to come back thru the regulator to ground, hence making my voltmeter on the bike go down for a bit (about 12v) then back up. So just b/c it looks like the regulator is doing it's job supplying the battery with what it needs, doesn't mean it's always good. This was a great learning experince to say the least, and thanks to this board I was able to troubleshoot this problem all the way thru. Onething I did learn, throw away that test light when checking regulators, stators ect. A digital voltmeter wont lie to ya, the test light did. That little bit of resistance in the test light I really feel was thedifference, for with the meter there is no resistance. Anyway, I'm on my way to the stealership to pick up a new one for 200 bucks! OUCH! Of course they did a check on my Vin# and no recalls or problems with that yr... (coulda fooled me, this bike only has 11k mileson it)they did say there was a problem with the 06-07's tho. While doing all the checking I did check my stator and it was fine. I will put a trickle on the battery overnight to see if I can get it back up to a full charge, hopefully it didn't hurt it. Anyway thanks to all concerned and I hope this helps someone down the road. Ride safe all!

 

What I think was happening when you used the test light to check for voltage in that circuit was interesting and I will explain (I hope). The test light has a very low resistance (typically a few ohms) while a voltmeter has a very high resistance (typically > 1 megohm). You have to have SOME current travelling in a circuit in order to measure the voltage in it, or, in other words, the current going through a resistance creates a voltage across that resistance. The higher the resistance, the less current is required tocreate the voltage across it. The circuit seemed to have some current limiting in it, so when you put the test light on it, it loaded down the circuit and the current available was not sufficient to light the test light. Conversely, the voltmeter, having a much greater resistance, did not load down the circuit and the small amount of current trickling in the circuit made measuring the voltage easier.

Anyway, glad you found the problem. Hope the repair is much easier!!

 

Thanks for clearing all that up dag. Guess I got my resistances back-asswards! lol I did get the new regulator on this morning and have ridden some and everything seems fine now. From what Harley told me this was kinda rare, I can easily see how a man could chase hisa** around on this one, escp if he was using a test light. Again thanks for the input. Oh yeah easy job installing, about30 minutes.

 

I wonder if a person could just change out the diodes...

Actually, they can. Since the input impedance is typically so high, it's not unusual to find voltage present in disconnected wires run in parallel with wires that are connected to a voltage source. Yes, the induced voltage is there, but there's so little current that it's inconsequential. Can really mess you up if you know you've lifted a lead from the breaker yet can't find the dead wire in a junction box.