Charging system not working...

[nathand]

I have a '95 Talon esi and the battery was shot, so I replaced it. Then the alternator went bad so I replaced that. I also replaced the battery connectors.
I don't really know what else to look for. The alternator isn't charging the battery. I had both the alternator checked and the battery checked, and they are both good. I also checked the fusible link, which is good.
Any ideas? I have been told to pull the wires and check for open areas where the wire may be exposed. Other than that, I am out of ideas..

 

[XTurbodTalonX]

If the alternator isn't charging the battery, you'll have the same battery voltage weather the car is running or not. When your car is running, you should have about 13.5 VDC or so between your battery positive and negative terminals. If it is 11 or 12 VDC, you are correct about your problem. If you have low battery voltage at your battery terminals while the car is running, try checking between the positive terminal directly on the alternator and ground while the motor is running. It should be about 13.5 VDC. That means there is an issue with wiring between the alternator and battery. If you have low voltage coming directly off of your alternator, then either the alternator or voltage regulator is malfunctioning. Your grounding system might also be to blame. Any metal portion of your chassis should have very little resistance (<1 ohm) between it and your negative battery terminal. Abnormally high resistance drops voltage and causes electrical components to work harder than they need to, or not work at all. With your car not running, and the battery disconnected, you can safely perform resistance checks on the necessary wires/cables. Just remember to isolate the component you're testing.

 

[luv2rallye]

Did you test the 120A fusable link with an ohmmeter (not just look at it)? On a 2g NT the PCM (aka NT's ECU) runs the alt field coil so if everything checks out in the above post, it may be the problem - then try swapping it with a friends 2g NT PCM. But first check that it's wiring and connectors are ok.

 

[nathand]

There is about 12V coming from the battery off and running. I checked it where it goes into the fusible link, also 12V. I checked it coming out of the alternator while running, also 12V. So does that point to the wiring or the computer?

 

[DSM1G90]

12vdc from the battery when running means the regulator in the ALT is gone (too many bad batteries in that car that caused the regulator to crap out-have to replace the ALT) ..

You should have 13.8vdc to 14.3vdc coming from the ALT when idling when you touch the VOM across the battery.

 

[GRAVEDIGGER]

If you have only 12v coming from the alternator, that's not enough. You should be seeing at least 13.5 volts with the engine running, or your alternator is not up to par. I would like to see anywhere from 13.5-14.8 volts on a good charging system.

 

[nathand]

So are you saying that I need an alternator that just simply puts out more or what? I don't exactly have a lot of money right now to just throw into a bunch of different things.

 

[GRAVEDIGGER]

So are you saying that I need an alternator that just simply puts out more or what? I don't exactly have a lot of money right now to just throw into a bunch of different things.

I am saying that your alternator is junk and you need a new one! If it's not putting out OVER 12 volts it is bad, regardless of what they said when you had it tested. The on-car test never lies. I can't tell you how many times places like autozone will pass an alternator on their machine, but it will be unable to produce enough voltage on the vehicle.

 

[DSM1G90]

I wouldn't got to Auto'CRAP'zone if my life depended on them...


Three of us have mentioned the facts of a charging system: Alternator keeps the battery charged since the battery is what runs the system in ANY vehicle.

to keep the battery charged, the ALTERNATOR has to put out more voltage - the 13.8vdc - to keep the battery at full peak due to the current draw that the vehicle requires in operation.

This is how a vehicle's charging system operates - can't get around it.

Your reading shows 12vdc which is too low to keep the battery charged and eventually will drain down the battery, and by these readings that you posted ususally are the results of a gone alternator.

You have to replace the alternator. In the mean time, put the battery on a charger each night and recharge up the battery until you get fundage to buy an alternator from an alternator shop.

So, we present you the facts. Ball's in your court to play now.

good luck - DSM

 

[nathand]

Alright. Thanks for the input guys.
I do know how the charging system works, I just wasn't really aware of the fact that an alternator can pass the in-store test and not work in the car.
I will be going back tomorrow and getting a different alternator then.

 

[luv2rallye]

I agree alt testing in any auto store is worthless and they are well known to sell bad new alts. The only place to get a real alt test (other than on your car) is an alt/starter repair shop. Take it back and try another. If that doesn't work check the wiring. And if that doesn't work suspect the PCM. 2g NT alts don't have a regulator in them. Regulation is done by the PCM controlling the alt field coil current.

 

[DSM1G90]

2g NT alts don't have a regulator in them. Regulation is done by the PCM controlling the alt field coil current.

Forgot about that with Chrysler .. They did like to do things different like FORD putting starter selenoids on the inner fender wells, or on the firewall...and GM putting HEI coils on top of the distributers in with use with expensive modules...

 

[GRAVEDIGGER]

And if that doesn't work suspect the PCM. 2g NT alts don't have a regulator in them. Regulation is done by the PCM controlling the alt field coil current.

I never knew that about the 2g NT's. Thanks for the info!

 

[nathand]

The alternator was bad and the PCM was also bad. So it was two things. Thanks for the help guys.