My 1998 Town and Country Lxi is suddenly showing a battery light. I had to put a charger on it to get it back to 12V. It wasnt long before it got down to 11.75Vand triggered the battery light to come on again. I want to isolate the alternator and was wanting to know if my model year uses a B circuit type alternator. I have read that I can test whether the PCM is regulating the field by checking for 12V on the dark green wire on my field connector.
Is this accurate, or shouldI do this another way ?

 

If it was me, I'd run it up to Pep Boys or Advanced Auto parts and let them do a free battery test. I am sure their tester could tell you if it is the alternator or battery and they will even put the battery in for free. No need to sweat until you need to sweat! ;-)

-Jerry

 

Ok. So battery is new Duralast, about 3 months old. 3 days ago I take the van to Autozone to have the on car test performed. The not so knowledgable guy hooks up to the battery, has me raise the RPM's to 2500 for 1-2 minutes and tells me the alternator is bad. No question. Really.
I go home and remove the alternator. Now I take the alternator to Advance Auto parts and they put it on their tester. The guy didnt seem to know what he was doing.
Anyway, he said it tested good. I dont want to rely on these guys since they dont know what they are doing. I may as well learn myself and do it right.

 

Hi
The PCM (engine controller) controls the alternator and it’s most likely the PCM is at fault I had to change one last week for the same fault. If you can get hold of a code reader that will give you sensor readings as you need to look at what the PCM is saying the battery voltage is. The one I did last week say saying the battery voltage was at 13.5 volts without the engine even running so when the engine was running it was turning off the alternator as the voltage was going too high. This would explain why your alternator and battery will pass any tests done on them.

 

Sorry RJDEV, I guess I am spoiled by the fact that the guys at the AutoZone near my house are pretty knowlegable fellows. The light came on for me one time and it was the battery, a Duralast that had only been in the car for about 8 months. It was replaced by AutoZone (or maybe it was Advanced auto) and all was well...

-Jerry

 

wn

 

We are on the road again. As it turns out the guys atthe Advance Auto Parts store did not run the test properly and got a false reading. I had suspected that something was done wrong, so I called and talked to one of the more knowledgable employees. He confirmed my suspicion that the guy that ran the test did it wrong. These test machines need to be setup properly for your application or the results are bogus. Hats off to a guy named Terry at Advanced Auto Parts who went the extra mile for me. He also got me a 20.00 discount which meansI got a 120A alternator for 125.00 with a lifetime warranty. Thanks to all of you for your posts.

 

I may have a similar problem. My battery light came on and when I checked the battery there is only 12V with the engine running. I naturally changed the alternator but still have only 12V. I had the original alternator checked and was told that it was good. I then made sure that there was indeed 12V going to the alternator to rule out the fusible link. I was told from the alternator lady that this alternator does not have a regulator and that it was controlled by the PCM. Any suggestions from you Chrysler guru's?

Thanks,

Randy

 

volt meter see if you have 12v at teh big red wire and teh control wires will ahve a ground and a pulse-with modulation signal on teh other see which you are missing

 

I have the same voltage on the alternator that I have on my battery with the car not running. This tells me that my fusible link is ok. The alternator has a plug with two connections so one is the field and one is the ground. How do I check to see if my cable is good? Most people are pointing me to the PCM being bad at this point.

Thanks for the reply,

Randy