I changed both batteries on my 2004 Dodge Ram 2500 Cummins Diesel and now my electric fuel pump relay repeatedly clicks and the engine won't start. The fuel pump was retrofitted by a dealer approximately 8 months ago to an electric fuel pump. The clicking has a steady tempo and the engine service light with the fuel light stays on with the ignition on. Relay fuse is good, bought a new relay-acts the same. Bought a OBD-II scanner and it wouldn't communicate with the truck computer. The scannner communicated with my wifes car no problem. Scanner manufacturer help-line said they couldn't help me unless the truck was running. Could changing the batteries have blown my pcm? How could I tell if that happened? Is there a way to reset the pcm? Left negatives off batteries overnight with still no change! My truck ran fine before the batteries were changed! HELP!!!

 

you could try taking the cables off and touching the pos and neg cables together for 30sec i know that will reset the ecm on a duramax dont know about a dodge for sure tho, never heard of one doing what yours is doing