I have a 2010 Dodge Ram 3500 dually with the 6.7 Cummins truck won’t crank or start will crank if jumping relay I tried to connect scanner to port and it says it can not communicate with the ecm/pcm would low battery voltage cause this to happen my batteries are alittle older I was going to Replace them but they were still working when truck was running I had a friend of mine install a tuner on it and that’s what happened after the tune the port would no longer read the voltage on the batteries were around 11.4 I know 12.6 is charged but I’m not sure if it would affect the computer not communicating or not or if some how the computer got friend if anyone could give me some ideas that would be great