Okay guys. Here's the problem: about a month ago I was driving the Evo and my interior gauges turned off, headlights shut off and I pulled to the side of the road turned the car off and it wouldn't start. Battery was drained, and I was reading 12.25 volts with the new battery installed (diehard platinum) and the car running. So at this point I thought it was the alternator. So I buy an alternator off a salvaged Evo. I bench test the new one and old one. They both pass. So now I'm really confused.

I install the "new" alternator anyways, reinstall everything and start the car. It still reads 12.25 volts. To make sure, I unplug the negative terminal from the battery while the car is running, and it shuts off immediately.

So now I check my fuses. Alternator is good, and all the other engine bay fuses are good as well. I check the interior fuses, those are good too.

I check my fuseable link, these are good, as far as I can tell, too.

Now, I'm thinking it's the grounding points. I've found 4 of them (don't know how many or if they are the right ones) and sand them off (even though they aren't that corroded).

Is there ANYTHING I missed or a way to check or any help you guys can give me at all?? It's been an ongoing issue and it's driving me insane. I'm this close to selling the car as is because I've cried myself to sleep the past couple weeks.

Thanks guys

 

maybe the old battery was just too old to hold the charge?

 

I have a brand new diehard platinum on there right now though..

 

Have you ohmed out the wiring between the alternator and battery?

 

Yeah, the power cord for the alternator reads 12.5ish with the car off and jumps between 2 and 6 volts when the car is on.

 

12.5 V is normal for when car is off. What do you mean jumps between 2-6 V when on? When your car is running it only shows 2-6 Volts? When the car is on and running, check the battery voltage. It should be around 14-15 volts... If not, then i would believe it is the alternator... but i see you have already tried a salvaged one.. How did you bench test them? I would double check that both cables going to the battery are hooked up, and not frayed or broken anywhere. I have not looked in a while, but i think there are 2 positive wires going to the battery.
I am curious how to benched the alternators though. There is a machine that can spin the alternator fast enough to get proper charge, but without it i am unsure how you would do that. Also i find it strange that both the "bad" alternator and good one both test good. Do you have an amp clamp? Try putting it on the alternator output wire and see what is reads. This is all i can suggest. Maybe someone more experienced can help.

 

From the power cord to the alternator the car read 2-6 volts with the car on. With the car off, at the same power cord to the alternator, it read 12.5. So there is not a charge being made by the alternator and it seems it's pretty intermittent.
Yeah, okay, so I took the two alternators to oreillys, an automotive store, for a bench test. They told me the problem could be intermittent and the bench test couldn't pick up on that. So what I just did was buy a NEW alternator which should be here Saturday. If that doesn't work, then I'm really going to need your help you guys. But

 

Guys, my brand new alternator (OEM mitsubishi) came today. I installed it and the car still only puts out 12.20 volts when it is running. I am honestly about to go trade it in for a jeep or tacoma. Please, if you guys have anything, go wild and post what you think it can be.

 

that's your concern? that it reads 12 volts?? or is it still not charging? Have you considered taking this to a third party perhaps more experience with the system?

 

the alternator doesn't charge the battery at 12 volts. It charges it at 2-6 volts. It's called an alternator because it generates an alternating current...from 2-6 volts. The battery generates DC current, which is a stable voltage, anywhere from 12-14.4v is fine at the battery. There's nothing wrong with the charging system.
the power wire on the alternator reads 12v when the car is off, because it is connected to the battery.

What changes did you make to the system before the lights failed? Think of anything, literally, anything, you may have done. I say this because I think you are above your pay grade when it comes to car electronics and trying to diagnose or repair this. I think you blew a headlight relay, but so far, you've replaced the battery and alternator. Is there a local stereo shop you can take it to? They are pros at vehicle wiring as well. But first, check that relay.

 

No these cars out out 13.4ish volts when they run. Otherwise it's just draining the battery putting out 12. I realize that it only puts out 2-6 volts to charge the system, but my problem is that those 2-6 volts are not being transmitted to the battery, otherwise it would be pushing 13-14.5 volts. Anyways, I took it to the dealer about a week ago and they found the problem, the Ecu is fried. Apparently it just got overloaded and something like my aftermarket stereo shorted the system.

 

ECU is fried?? Woah. From the stereo? I'm intedested in what they find!

 

I'll definitely let you guys know.

 

i can tell you to never pull your negative battery cable while the car is running as you can fry ecus easily by doing that with the computer controlled alternators. i dont know if you tried it before but just an fyi