AJsArmor

But with an alternator mounted, nothing plugged into it...and taking a voltmeter with the ground to the case and the positive to the output terminal, should read greater than 12 volts? With the engine running of course.

Reason I ask is I just bought a new alternator, no output. And that's measured at the alternator, vehicle running, nothing plugged into it.

GSGALLANT

You have the alternator belt installed, right? JK

Do you have the electrical connector plugged in on the alternator? I'm not sure about this... so it's just a guess, but you might need that connector plugged in for the voltage regulator to allow the alternator to supply voltage to the output terminal.

If you do have it plugged in, maybe you got a bad alternator.

TNRabbit

Many have to have some sort of "kick" or draw to start them up....maybe that's the issue. Try that with it plugged in.

chewie1014

What he said. I seem to remember that you need to plug it in to close the circuit and provide juice to the output terminal.

AJsArmor

Well just plugged it all in as normal, threw the lights and heater on high to give it a draw...and the voltmeter read 11.5-11.4 at the battery with the charge/brake light still glaring on. All my cables are 4ga with soldered ends, rechecked those along with the plug into the back of the alternator. Checked it to the fender and it had good continuity. Had 12 volts to each one with it unplugged and ignition on.

Must be a dead one right out of the box I guess, my luck. grrrrrr

TNRabbit

If it's a ty Advance/AutoZone/etc., yes, the come that way frequently. Stick with OEM and have these guys rebuild it for you for 130 amps!

Boyle Future Technology

Do a search & you'll find their address/phone etc. They do a fantastic job.

DeathCougar

iTrader: (23)

Aftermarket FTW!!!

86tuning

Test the three wires on the plug before you do anything else.

With the ignition on, all three terminals should have +12v. The big fat wire on the 10mm should also read +12v all the time. If they don't, you don't have an alternator problem, you have a wiring or fuse type problem.

iamsuperbleeder

what does FTW stand for anyway???

I'm pretty computer/internet literate, but I still don't know that that one means

it took me forever just to figure out what IIRC mean; I had to figure it out from context-clues, lol

BigBluePile

iTrader: (3)

For the win...I think!

DeathCougar

iTrader: (23)

FTW= For the WIN

desconhecido

Ok, that helps.

AJsArmor

The socket was pretty nasty so I checked that and it did read +12v on all 3. BUT I took the alternator back and they tested it, tested out fine. He even ran it through the cycle several times, no problems and a strong 14 volts. So now I'm thinking it's gotta be a bad connection. I took some time and cleaned out the socket really well, doused it in electrical cleaner and we'll see what happens tomorrow.

FYI-I have a 4 ga ground going from battery to header panel/ battery to engine block (right behind the alternator), and engine block to firewall. Rechecked all of them and they are good but can't hurt to go over them once more I guess.

RobD

Check belt tightness or replace it.

AJsArmor

It's spinning it just fine, not like there's any real load on it from the alternator.

bigt

where i come f rom FTW means eff the world.. wow all this time i though yotatech was saying that LMFAO

thaddeusss

no... you won't get anything that way.

the field in the alternator needs to be excited to put out any juice.

if it put out juice without being excited it would be a generator instead of an alternator.

abecedarian

With everything unplugged, the regulator should take alt output to max: since it's reference is 0 (since it's unplugged) and it wants it to be ~14.5, the alt output goes to the high end. Could actually read over 18v (remember the relation between volts and amps- voltage and amperage are inversely proportional another reason to not disconnect the battery with the engine running: voltage sensitive devices can be fried if the battery is not there to absorb transient voltages [act as a load to absorb high volts and convert it to amps]...).

AJsArmor

SOLVED! And man do I feel like a moron but it was the 140 amp circuit breaker at fault. That was actually the very first thing I checked, unhooked both leads and flipped the DMM to ohms....fine and dandy so I never rechecked it until now.

Turns out that the contacts inside must be bad/dirty/cheap junk because just a slight bump and they open without the breaker actually being tripped. So I could measure it ten different times and it would pass or fail at random. Serves me right, it was an el cheapo...I put a quality one in there, fixed.

GSGALLANT

...and here we thought we were trying to help you fix a problem with your stock system.