welcome to the arduino-forum.
I'm pretty sure that you agree and will follow the way how to solve your problem mimimum 200 minutes faster.
This requires to invest 20 minutes of your precious time to read how to speedup solving your problems.
Directly after registering you got presented informations how to speed up solving your problem.
You should really read it.
Are you talking about a real truck?
Well-llll theeeennnnn take your iPhone install the universal engagement app and connect your iPhone's earplug-socket with your motor.
You think "this can not work"
you think that I'm kidding?
Yes I'm kidding.
if you are talking about a real truck you seem to have a way too naive imagination of how these technical things work.
First of all your ECU is a safety-relevant part of your truck. If you do only the slightest modification to this ECU you will loose the general operation allowance. If anything happends you personally will be in charge if it runs bad for millions of dollars.
Ask the manufacturer of the upgrade-kit if this company has a certified ECU for this kind of transfer-case.
best regards Stefan