Like
@retiredsparky stated, the fault is most likely within the wires or connections. You will have to really do some digging around and I hope you have good eyesight.
besides that, you need to develop some perspective on the electrical loop and how to properly diagnose it with designed tools like a voltage meter and test probe/light. The workshop manual for the applicable vehicle as it was orig manufactured will provide information regarding the spec current at each wire at key off/key on/accelerator pressed/idle and so on. Given the proper tools, a person finds the fault when voltage is present when it should not exist & vice versa, or the numerical value range in a specific power mode does not coincide with technical specs in your literature. The problem can be anything from a battery performing below specs to a oxidized/contaminated connection, loose connection, poor ground, exposed wiring, etc etc.
this is why it is so difficult for somebody to tell you what exactly is causing the problem you have. Your options are:
1) research and DIY
2) hire a mechanic that is familiar with engine swaps
3) search the Internet using various combo of key words & phrases until you find the info that you need. This or something similar has come up before, you just have to keep searching until you find it.
Consider the purchase of a workshop manual or extended resource as it applies to the original donor vehicle of the engine you have. The section for the motor will obviously be of great benefit. I remember browsing through there a while back when the accelerator pedal sensor (same drive-by-wire you now have) failed on my truck (gmc Yukon) and I found the schematics for that system, which is the number 1 thing that you need right now.
Since the problem was exacerbated with the newest donor wiring, inspect the connections of where the wires tie-in at both ends of your recent work as a start. If you could acquire some tools that is where I would be testing voltage as well. There is a certain volt at each wire & connection at key off, with key on, engine idle, accelerator pressed. That is what you would be looking for, shop manual as reference in-hand.
I was just thinking and has the accelerator/throttle ever worked as of the transplant?
What engine was original to the Patrol?
There are other things to consider here. You may be in need of more parts & pieces original to the GM DBW.
The definition of those codes for starters. Do you know what each of the codes mean?
Have the fault codes been there since the beginning?
