I have a 5.9 cummins diesel. The battery will not stay charged. Took it to NAPA had it checked...works fine. Had the alternator checked and it is working fine. Check the fuse it is fine and it has new connectors from alternater to battery. Does anyone have a guess as to what might be wrong?

 

did you have it load tested both of them

 

The battery was load tested and the alternator was put on a machine and it said it was putting out 15 volts

 

sounds like you have somthing drawing amps off of your battery or possibly a dead short so start looking

 

Thanks for your help

 

sorry i couldnt tell you alot more but its kinda hard to tell what it is without a little more info will your truck not start or what else is it doing besides your batteries arent staying charged

 

since you have checked all of the above check all your gounds going to the frame ect... then i would clean the crank position sensor. that could be the problem, just my 2 cents as when i did my kdp i did not gap it right and my gen light would stay on. re gapped it and fixed the problem.

 

The only sensor I could find is on the harmonic balancer, Do you know what the gap should be? Thanks

 

that is the one you want and i believe it is .050 hope this helps

 

I am going to say you have a bad ground connection and its not charging your battery