Quick question...is there a way to test the alternator? Been having some electrical issues....had a optima redtop where it would go dead after a week....replaced it with a new one...still seems to be weak...could it be the alternator isn't charging it? I noticed now they clock and any other lights seem to flicker to the same rhythm as the rpms of the engine.....when I bring up the battery voltage on the DIC display it reads 14 to 14.2 volts. Just wondering if I need to replace the alternator or there could be something else going on. Thanks in advance.

 

14 to 14.2 volts is what the voltage should be when the car is running, if the alternator and its voltage regulation are doing well.

If would clean all the terminals (both ends) of the battery cables (both cable end and what it connects to): sometimes a bit of corrosion can actuall do this.

If it does not help then:
1) do you drive the car every day, if so you have a problem, some short or something left on -- going to require some effort to diagnose.
2) does the car sit for a week or so between times you drive it? If so you need a trickle charger.

 

Mr Willis,

I had it on the track Friday thru Sunday...and it seems hesitant to start..even with a brand new battery.....I'll try cleaning the terminals......I don't drive it everyday...but my Tahoe can go 60+ days (while I am deployed) without being started..and the Optima battery is fine and starts up ok.....the old optima battery I had in the vette would be completely dead in less than 2 weeks.....but when it was ok...it started a lot better than the new one does now.....I haven't let it set for a week or more yet to see if the new battery will do the same thing or not.

 

Just got some numbers of the voltage while in idle.....it flucuates between 12.7 to 13.7 in idle. You can see the MPH, clock and temperature readouts all kinda flashing in idle....also I noticed, when I hit the brakes, it will do the same thing....I know most cars do this, but when I lower the windows, the readouts get very dim...more so than I've noticed before....or maybe I'm smokin' something too.....Just seeing what your guy's thoughts are??? Thanks!

 

MIne does not do that and I don't thik the car is meant to do that, so, yeah, you have a problem. Sometimes places like Autozone can test your alternator for you before you buy a new one (concievably it could be some other problem although I hope not, it would be a bitch to find). You might ask.

 

Got multi-meter?

Put it on the field terminal on the back of the alternator - usually a medium-guage red wire. Ground it, and check the #'s. Should be 14V+, like LW said.

THEN, go to the positive clampat the battery, ground it, check the #'s. Should be slightly less than at the field terminal.

NOW, check the actual battery positive terminal itself - NOT the clamp. (You'rechecking the clamp-battery connection). Ground the meter; check the #'s. Should be the EXACT same as the positive clamp.

 

Thanks guys....I hope to get this figured out tomorrow.....With an optima battery and the connections on the side....not sure how to check those things you said cwb....I guess I could use the terminals on top...and then the clamp on the side to check the clamp-batter connection, huh?

 

Well....I think I may have found the issue. I did as you said cwb.......getting 40A from the alternator with right around 14V. Getting around 14V at the battery...ok, well technically like .1 less than what is at the alternator. The connection between the 2 are fine...same numbers there. So I took it to a place to check it...see if I messed up.....they showed all the same numbers...and they said they think my alternator is fine...the fun was, he did a check on my 1 month old Optima red top battery....his tester said it was at 15% charge (based on him entering the CCA into the tester)....which makes no sense after driving it some today and yesterday....the Optima should be able to hold the charge for like 60 days (according to Optima) and I start my Tahoe up with the Optima after sitting for over 2 months.....so it would appear my battery isn't able to be charged very effectively....which, does this sound right, the guy told me the reason my clock (and all the interior lights)is probably fluctuating is that my battery isn't able to absorb or even out the drawon the system...so it is relying almost purely on the alternator's power...which would explain why everything seems to pulsate to the rythm of the engine...and why the lights dim when I hit the brakes????? Go figure, for me to get a bad Optima battery off the shelf!

 

Yes, I would think... Of course, that does then assume PERFECT internal connectivity between the battery's top post, and the battery's side post. Probably a safe assumption tho'...

 

Pilot, as in KC 10? KC 135?