Battery Problem

[trm1978]

My brother in laws 08 3500 Auto dually 4x4. Keeps running the batteries down. He can not figure out why. Every morning he gets up the batteries will be dead. Jump it an it will last all day. He replaced the batteries did not fix. Know it they the trans into limp in mode an the dealership wants to replace the transmission for 3800. 00 dollars. Has anyone else had this problem. We took the truck to transmission guy we trust he said it is not the trans. He replaced the altenator just waiting to see if the batteries go dead again. So far the trans is working. Any help would be nice. The only aftermarket part on the truck is ts mp8 box.

 

[Road Dog]

There's no end of modules that can draw down the battery. On 2nd gens the seat belt lock would stay energized and kill the battery. You have to hook up an amp meter and pull fuses until you find the load.

 

[jelag]

Nothing worse than someone replacing parts when there's nothing wrong... Road Dog's right... I'm betting there's nothing wrong with either the batteries or the alternator...

Go get a good scan tool... The one I bought was on amazon for $135 and in the parts store for $300. 00 its already saved me that... my 08 is out of warranty at 110K miles...

Still the OE batteries and alternator... actually all the parts are still there...