dajodsterman

Hey guys, all of my lights are pulsing (ie headlights, courtesy, console) at idle. Sometimes when I'm driving and I let off the gas the voltage drops pretty low for a couple of seconds. I don't have any kind of sound system and AutoZone tested the Alt. and said it was ok they're not sure what is causing the problem. All the battery leads are tight. Could it be a bad tensioner? Is there a way I could check it? Thanks for any info you might have.

sprydncamd ta

iTrader: (4)

see if u can move it by hand. When mine went bad the belt came off. But my mechanics at harris speed works said u shouldnt really be able 2 move it by hand.

dajodsterman

It didn't move by hand untill I really shoved on it. It has a slight bounce in it with the motor running. Is this normal? Also the belt looks old. Could the belt be slipping causing the pulse? Has anyone else had this kinda problem with voltage before?

gwj

I would have the battery checked, just as a matter of course. But I would almost put money on the alternator. It may crank out the amps when they spin it up, doesn't mean it functions right all the time.
Let us know what you find out, curious.

dajodsterman

The Alt. was the first thing I thought of, but after going to AutoZone I started looking for other things. I think I'll go to a different place and have them check it. BTW AutoZone checked the car running, at the battery terminals. Not sure if that makes a difference???

gwj

I wrongly assumed they did a bench test.
Well, they were checking the voltage output. Did the voltage (as measured by them) fluctuate up and down, or remain steady? And were your lights doing the pulsating thing during the check?

dajodsterman

I didn't look for myself to see if the voltage was fluctuating. I guess I should have though. I didn't have the headlights on so I don't know if they were pulsing then or not. I guess neither me nor them did a very good job of trouble shooting lol. I'll have to do another check and try to pay a little more attention this time lol. My biggest concern is the big voltage drop I get for a couple of seconds sometimes when I'm driving and I let of the gas at slow speeds. Sorry the info hasen't been that good.

nickls1

iTrader: (2)

Do you have anything else running like the a/c? I had a similar problem on an older car of mine, but it only happened when the a/c was running. See if there is anything else causing excessive resistance.

You may also just have a bad battery or something. If its not sealed, check the cells to see if one is dry.

Take the drive belt off and spin the alternator pulley manually, if it has play in it you may have a bad bearing.

75tonyA

iTrader: (6)

I have had alternators partially blown. They still worked but just not as well. I use an ociliscope to test it while the car is running. You separate the battery in the circuit and it measures what the Alt is putting out. Sometimes they have only few diodes are out. Try and find someone with one of these tools.

Hope this helped.

dajodsterman

sounds like that's the problem. I'll see if I can get it tested that way somewhere. If the test is positive should I replace now or wait for the alt. to get worse? Could it cause any problems with the elecronics or the performance if I don't replace.