My truck has been being a pain to start these past few months, and now with cold weather, its worse.. When i just turn the key on, the volt meater neadle goes to just the first line. (I think its 10) but once started, it show normal, the neadle is strieght up on 14. So i got new batteries that were under warrenty. And still the same thing!!! So is my Alternator going bad?? Is it not charging the batteries up all the way?? Oh and also when first started the lights get bright and dim alot.. I need to fix it, it was about 10* the other night, and it only cranked for about 3sec and left me stranded!! Thanks-Chris

 

The cycling and dimming jut after starting is normal if less than 50 degrees outside. It is your grid heaters cycling on and off. They usually cycle fairly rapidly when first started, then the cycling slows down after it starts to warm up or when the truck reaches speeds of 10 to 15 mph. The cycling sounds normal (volt gauge needle drops down for a few seconds, lights dim, then jumps back up to normal and lights get bright, then repeats after a few seconds-is normal).

I had the same problem, batteries were good 1 year old optimas, but the starter sounded slow. It sounded like weak batteries. Turns out the brushes on my starter were about gone. Worn down as far as they could go. This sounds like your problem. Slow starter is brushes, failure of the starter to engage is starter contacts going bad.

You will need to pull the starter and take apart to replace the brushes. There are 4 of them, but probably only two are bad. Replacement brushes can be purchased locally or at LarryB's also known as Foster truck. Here is the link:

http://www.fostertruck.com/dodge/

Read that first page, he sells the brushes, has instructions for changing them, and you might want to consider giving your starter a tune up by replacing the contacts as well since your in there, the contact failing is a common problem, the brushes are just considered normal wear.

EDIT: I just re-read your post, sounds more like your alternator not charging the batteries or a power drain, new brushes for alternator can be purchased from LarryB, but I would check all battery cables, hot and grounds, clean all connections including grounds at the block, check and clean positive cable connections at starter and where they connect to each other. A quick voltage check should show 12.8 volts when everything is off and truck not running, 13.5 (or more) volts whith truck running at idle (this is cheking voltage at the battery posts with a simple volt meter). If that is normal, then I would go back to the brushes or contacts. KD

 

To me the starter seems ok, when you have a bat charger on it, it cranks FASS, and just turn the key on, it shows normal volts.. The starter is only about 2yr old. But i'll keep this in mind!!

 

Take a volt meter and test the battery while the truck is running and after it has warmed up. If it reads 14.2 or more your alternator is good to go.

Let the truck sit over night, and then check it again with the volt meter. Make sure you don't have the light on under the hood. The volts should read 12.4 or higher. If not you either have a drain on the batteries somewhere, or your batteries are bad.

How old are the batteries?