I was driving my truck two days ago and today I tried to get my 2001 2500 Cummins started but when I unlock the door it makes a ton of clicking noises and when I put the key in the glow plugs don’t cycle and I can’t get the starter to go. I thought at first it was my battery charge but I charged them up and I still have this problem.

 

Check the connections at the battery(s), sounds like it just isn't getting a good power feed, or ground.

 

Cummins don't have how plugs they use grid heaters which I think get power from the ASD relay