replaced alternator, still problems!! Help Anyone?

[r/t brian]

1995 neon sohc

On sunday i started the car to let warm up cause of the cold. It warmed up for about 15min and then i jumped in and turned the lights on and i noticed the interior lights where pretty dim. So i took it for a drive and the radio shut off, all guages would jump at idle.

BTW 185,xxx on it but its still a decent car.

Decided it was the alternator not charging, replaced it and i get the same problems. Could it be a possiable bad new alternator or could something else caused this?? I read through a bunch of threads noticing people having problems with the car stalling after it warms up but nothing with the car not holding a charge after it warms up....those people seemed to have replaced the crank position sensor but would this have anything to do with the car holding a charge??

I cant get to the car til the weekend so im hoping someone can help me out before then.

When i get home this weekend im gonna try to disconnect the battery while the car is running to see if the new alternator is bad, i dont know any other test to do. I do have a scanner which i shoulda used in the first place to check codes so ill do that also.

Thanks for reading
Brian

[das2123]

Did you get the battery checked? Are all your grounds clean and tight?

[r/t brian]

Originally Posted by das2123

Did you get the battery checked? Are all your grounds clean and tight?

The battery was bad got a new one under warrenty but still not charging, with the car running I pulled off the positive cable on the battery and the car died. Got a code 41 which is a short in the alternator field circuit. And a code 45 which is the ambient temperature sensor

There is an alternator internal open or short or a PCM failure from what i read up on the code 41 but no idea on the code 45

Where is the field driver circuit? or what is it?

New battery and alternator

Im thinking its the pcm

[denisond3]

I think the 'field circuit' includes the part of the PCM that does the voltage regulation for the alternator, and the wires from the PCM to the alernator field coil. These would be the small wires in the connector that plugs into the alternator. The large wire at the alternator is the output, and connects to the battery. I would guess you have either a melted wire or one that has rubbed against something - and is shorted out. All the PCM knows is that it isnt able to send voltage to that field coil. The field coil in the alternator is the part that spins. Putting voltage on that coil, via the field control circuit creates the spinning magnetic field that produces the heavy current output voltage.

[r/t brian]

Originally Posted by denisond3

I think the 'field circuit' includes the part of the PCM that does the voltage regulation for the alternator, and the wires from the PCM to the alernator field coil. These would be the small wires in the connector that plugs into the alternator. The large wire at the alternator is the output, and connects to the battery. I would guess you have either a melted wire or one that has rubbed against something - and is shorted out. All the PCM knows is that it isnt able to send voltage to that field coil. The field coil in the alternator is the part that spins. Putting voltage on that coil, via the field control circuit creates the spinning magnetic field that produces the heavy current output voltage.

Thats what my problem was....a bad pcm. Got a different one and that fixed my problem. Also fixed my battery light that stays on the dash, it called a battery temperature sensor. Nothing offered aftermarket or by the dealer i got one off of ebay and that cured the stupied issue of the battery light staying on the dash.

Thanks for all the help and hopefully this will help others in the future.

Brian