You might find one that can control the signal from the ecm to the relays, but its pretty simple to see if you get voltage to the relays momentarily when you first turn on the key on a cold engine.
I'm not sure on a 01, but later vehicles, the ecm, bcm etc, sends data to the gauge cluster. So if your data bus is not communicating you will have no gauges.
Did they just legalize deletes? Will our tuners be able to start up again? My 2018 is finally out of warranty, so i would like to do some egr and DPF preventative maintenance.
Are you plowing with tow/haul on? That makes it charge higher. And the load from plow lift can be a pretty big drain. Hopefully you have the + side of lift on one battery and the - on the other.