Alternator won't charge.

[tryingbe]

I already went and read everything about the voltage at mini mopar at least 3 times.

Car is a 85 GLH-T with 89 2.5L, 87 TII 3bar cal, 90amp denso alterantor, etc...

Alterantor was charging perfectly fine at 13.5v, then I changed the pos battery connector, welded the exhaust in, and some other small things that I can't remember. Next time I went to start it, I notice the fan was on right away and the car was running off the battery, below 12v. Code 16, the car says. Revs maked NO difference in voltage out-put. Battery puts out around 12.4v when the car is off, 11.8 when the car is running. I had make sure the battery was completely charged with a battery charger.

Tested the alternator field coil terminals and the voltage is always lower than it should be, according to mini mopar. Tested with 2 alternators, same thing. Test with a known good extra computer under the hood, same thing. Final kick, bought a new connector and new old dodge truck style external voltage reguatlr and set it up as BFnGA said, http://www.turbododge.com/forums/showthread.php?t=83873&highlight=dodge+regulator+voltage, all result in less than 12v when car is running.

Tested the resistance of the alternator pos wire from alternator to battery, fine.
Tested the resistance of the alternator neg wire from alternator to battery, fine.
Checked, doubled checked and trouble checked all positive wires and makde sure I connected them all. Checked the engine ground and body ground. Checked all the fusible links, all the connectors around that area of the car, all checked out fine.

I spent all day today trying to figure out what's wrong and at the end, car was still running less than 12v.
I'm going to the part store to have one of the alternator be tested, but I really don't think the alternators I have are bad.

What else am I missing? This is the ONE last thing preventing me to take the car to emission test and get it register to my name!!! Please help.

[SpoolinGLH]

while your at it.. definatly check the sense wire..

http://www.turbododge.com/forums/showthread.php?t=101451&page=1&pp=15

[turbovanman²]

What type of battery terminal did you use, was it painted? if so, I bet you didn't scrape off the paint, I had a car towed in for this, he replaced the battery and alternator, doh!

Are you sure you reconnected ALL the wires when you changed the terminal?

[tryingbe]

No paint on the connector. I checked the resistance from the battery terminal to everything. Yes, I spent the whole day making sure everything was connected.

How do you check the sense wire?Have the car running and?

I also started the car without the pos alterantor feed line connect to, the car runs the same as with the alternator feed line.... :confused: And I know that line is good, I mean, I checked the resistance on it at least 3 times.

[cordes]

I put a ND alt. in my omni, and the fusable like went. I now run a wire directly from the alt output to the + bat terminal.

[tryingbe]

Fusible link is good, I have 2x 80amp fusible link set up just like how mini mopar said that's the way to replace that link.

[SpoolinGLH]

dude read that link i posted... do you have a multimeter??? thats all you have to have in order to check the sense wire... and that link i provided tells how much voltage the sense wire should be running and not running

[tryingbe]

I read the link you posted.

I asked you how to check it, ie. take wire 22 out of the blue connector oflogic module and check the voltage there or what?

[Clay]

did you try to full field the alternator and see if the voltage jumped up like it should??

clay

[tryingbe]

What's "full field"?

[Clay]

the field voltage on the alternator should be somewhere between 5 volts (low demand) and 10 volts (high demand). This varies the amp output of the alternator based on what the LM tells the alternator it needs.

To check and make sure your alternator is good, you can full field the alternator, ie apply 12 volts across the field lines. This is exactly what the machine they use at the autoparts store to check alternators does.

clay

[tryingbe]

Car running, only got 4.xx volt.
Turned on heater, headlight, rear defrost on, got 8.xx volt

I'll try to do that again tonight.

[tryingbe]

Didn't get a chance to do anything other than took the two alterantors to autozone. They both tested fine.

[85shelbycharger]

Try changing out your logic module. I was having issues with my Shelby Charger a couple weeks back and I went through changing 4 alternators and checking fusible links, amongst a million other things...and it turned out to be the logic module.

[tryingbe]

Tried that already.
Swap in a known good LM and didn't change a thing.

[Stevien1]

The voltage regulator is in the power module (next to the battery), not the logic module (inside the car).

Did you unhook the neg battery cable when you were welding on the exhaust? I've HEARD of welders shorting out electrical stuff from backfeeding through the chassis ground(s). If I remember, I unhook the battery if I'm going to be welding on a vehicle. However, for all the times I've forgotten, nothing has shorted out! ;)

-Chuck James

[Clay]

The voltage regulator is in the power module (next to the battery), not the logic module (inside the car).

True, but the LM controls the voltage regulator ;)

[turbovanman²]

Ok, this is what you need to do.

Check for power at the large wire at the alt, if no, fix it, this goes to the battery.

Turn key on, check for power at one of the field wires-one should have power, and sometimes both will but we don't care about that. If power, then continue, if not, check wire then replace the module-PM I believe.

Start car, check voltage-now ground one of the field terminals, one will make it start charging, if no, the alt is bad. If yes, the PM is bad.

Disconnect both the field terminals. Hook up one wire to power at the alt, then start the car. Ground the other one, if the alt starts charging, PM is bad. If no charge, Alt is bad.

[tryingbe]

Will try it tonight, had to change the oil pump shaft seal and waterpump last night.

[tryingbe]

My friend was messing something under the hood and suddenly the car was running 13.5v. Took a drive around the block and then it's back down to under 12v.

I think one of those field wires are bad. I'm gonna replace them tomorrow and see what then. Is 14 guage wires good enough as a replacment?

Thanks.

[turbovanman²]

14 ok but I think 12 is whats stock.

[tryingbe]

Those two small wires are 12 guage? They feel like rubber most of the time..

[tryingbe]

Replace those two wires, didn't do a thing.

Went and measure the voltage at the voltage sense wire at the LM, blue 22, car instantly ran better. Change the connector at that wire and car runs perfectly fine with voltage at 13.5v with headlights on. :)

So, it was NOHTING under the hood that caused the problem. It was that connector all along, at least it's not one problem fixed. :)