I am going to at least begin this mod today. I just received my 150amp breaker yesterday from Amazon, I'll still need to pick up an online fuse holder for the pcm as well.

 I do have a couple of quick questions.

 1. What size fuse for the PCM? I read both 7.5amp and 5amp. 

 2. I read that the ac noise would affect cruise control somehow on a manual truck. I haven't used my cruise much, just wondering how it affects this? Any other things it could mess with?

 I will take ac noise readings before and after to see how this works out and report back when finished. 

 Since unhooked this morning no issues, no warning lights either. 

As long as the relays stay in place, and you just unhook the main power lead, you will not show an error in the PCM.

 

The computer is kinda stupid.  It only checks that there is resistance in the control circuit.  (that is how it knows there are relays there to be cycled.) It does not CONFIRM that power flows from the battery to the grid heaters. 

 

So basically, if you leave the relays in place, the computer thinks everything is kosher.  It doesn't know you have it relaying nothing.....

 

Hag

 I'll leave them unhooked for now, I will get them replaced before long but leave them.unhooked until the weather requires them again. No sense in straining the batteries if not needed.

Nothing to worry about... Grid heaters for Idaho are only suggested to be used from October to April. After April I typically just unhook the grid heaters its just a waste or power.