I'm new to the forum world so please bear with me. I've been having troubles with my 06 cummins that nobody seems to be able to figure out. It started out by losing voltage while driving home. It threw 5 different codes all at once in the following order: P2509, P2503, P2502, P2146, P2149. The first 3 have to do with low or intermittent voltage (I would assume the alternator). The last 2 have to do with open injector circuits. So I took it to my local auto parts store where they tested the batteries where one of my batteries was low so we charged it to 100% then tested the alternator and it passed. After charging the low battery back to 100% and testing the alternator, the codes cleared for most of the day. I drove it for a couple hours and the check gauges light came once again and the same 5 codes appeared. After charging the battery again I used a voltmeter to watch the voltage myself. Before starting the truck it was at 12.90, then once started dropped to 12.50 and continued to drop very slowly for the next 30 minutes down to the high 11's so something is obviously not working right. After reading various forums and talking with different auto parts store people, I've narrowed it down to either bad battery(ies), bad alternator, or bad ECM, all of which would cost close to $200 each to replace with no guarantee of fixing the issue. I apologize for length of this thread, but does anyone have any idea what could be wrong?

 

Also, something about adding an external voltage regulator might help bypass the ECM, but they weren't sure what that would do to the computer in the long run.

 

how old are your batteries

 

any updates