I have a 99 Dodge with Cummins Diesel.
Here lately it has been overcharging the batteries until they start smoking. After about a week of not driving the truck, the batteries go completely dead.

Dodge has told me that the ECM controls the charging system, and that the alternator doesn't have diodes or a regulator.

Help!!! Not sure where to begin besides testing the batteries.

 

More info , how old are the batteries ?
Is the truck stock , including radio , every thing electric ?
Do not go to that Dodge dealer again , 1st your going to pay more in labor & parts most of the time , there are diodes in the alternator , thats why its called an alternator , it produces alternating current , 3 diodes turn that into DC .
If the batteries are bad they can make the alt charge full time , and other possibilities , very rare that the ECM is bad .
Find a good rebuilder , have them check it out , there are some special tools needed to get it done right , so that you only buy just the parts you need , like a load tester .

 

"Do not go to that Dodge dealer again , 1st your going to pay more in labor & parts most of the time , there are diodes in the alternator , thats why its called an alternator , it produces alternating current , 3 diodes turn that into DC."

To be fair to the dealer, perhaps they were referring to the diode trio which only produces the current required for the field circuit. They probably did not mean that there were no diodes at all in the alternator. BTW it is usually six diodes that rectify the AC alternator output(two diodes for each of the three phases)

 

Amperage draw test would be required to see whats causing the "drain". On the "over charging" the first thing I would do is to be sure the batterys and cables are good. Next would be to monitor the "target voltage" and "actual voltage" with the DRB. I would also tap into the sense wire that the JTEC uses to monitor this.

 

Good news. Apparently I had one of my brand new batteries as of a half a year ago go bad. That caused a direct short and burned both batteries up causing my entire problem. I replaced both batteries, drove for two hours strait, and neither battery started smoking or got hot. Problem resolved i think.

Thanks for the help.