Please need help! 1998 Ram 2500 Cummins 24 valve turbo diesel. Laramie SLT. 122,900 miles. Has both batteries new this past summer.Had it jumped 3 times since. Batteries tested good every time. Now just had it towed to dealer. They said the batteries are bad. OK, the batteries are under warranty. But they said the idle was at 2500, and it needs a new computer board. I've always known it practically drives itself on idle. Is the high idle killing it? Thank you so much for help.

 

Welcome to DF! May want to post in the diesel section..... As for any other issues, 2nd gen ram section.

 

There really are only a couple of ways i would think could destroy brand new battery's. The alternator could either be bad and draining or overcharging the system. Or the computer could be bad internally and grounding the system out causing the battery's to drain. The high idle shouldn't be affecting anything, just a symptom.

 

could be a bad cable connecting the 2 batts