How hard to replace dash wiring harness

How difficult would it be to replace the dash wiring harness? I’m installing power windows mirrors and locks in a 2012 standard cab which doesn’t have the wiring for them already. I’m in between building a stand alone harness just to control those items or pulling the harness from an access cab and installing that. I just honestly have no idea how difficult that would be. Any insight is appreciated

 

What year?

 

2012

 

These are the connectors from the door to the dash for the power windows.
Verify you have a fuse in the cab fuse box and wire to the connector, verify juice(12V) to it. It may have a wire to one side of the connector.

 

So I assume wiring that into the fuse box would give me power to the door harness, how then would I control the power mirrors and control the passenger windows and locks from the driver side

 

You might have this set up:

 

Find if you have the power to the connectors first or even have the connectors...

Driver's side harness has: remote mirror control; Power door lock/unlock; power windows controls; Power window motor; mirror turn signal.
Passenger's side harness has: (remote mirror input); Power Door lock/unlock; Power window control; Power window motor; mirror turn signal.

P.S. Forgot door speakers for each side...

 

That’s the problem is that the connectors are not there in my truck at all. I got everything installed in the passenger door and when I went to plug it in there was nothing. That’s why I was asking would it be insane to try to replace the dash wiring harness with one from an access cab that had all of those wires, or should I stick with my original plan which was to design a stand along harness that’s sole purpose is powering and controlling the power windows mirrors and locks.

 

If it were me I'd just run a couple of wires from pass to drivers side and attach to the appropriate connections. That's a crap-ton easier than tearing out/reinstalling the entire harness.

 

If you get the harness, it's all taped up. You would have to undo it, then select just the wires/connectors needed off the full cab harness. Doable...
I haven't inspected a single cab BECU to verify if it has the same internals. This is where they branch out to the systems.
You got a pic to post of the cab fuse box (BECU)?

 

OP, is it a 4 or 6 cylinder?

 

It’s a 4 cylinder. I’m certain that wiring it manually is the simpler solution, but wiring diagrams are extremely confusing to me and I don’t really understand relays and fuses well enough to confidently design a system that both works and is safe. While I am confident that I can unbolt and pull out the dash and then unplug and swap out a harness.
Also the guy that has the parts truck suggested pulling the fuse box and harness from the access cab and putting it all on my standard cab

 

That might work...

 

Connector 1F is for the rear right door )), so adding 2 terminals (090/2.3II female) to that connector will get you the power lock/unlock for both doors.
Now you have to verify if the male terminals are in the socket...

 

These are the door switches, door lock switches and the lock detection switch inside the power lock assembly, to the power locks. The all go to connector 1I in the rear of the cab fuse box. (BECU)

 

Door Lock/Unlock assemblies detail:

 

Options for adding wires to connector 1F:


But only if the system (lock/unlock) can be "activated". Door Key & door switch and everything else. (remote add)

 

I’ll try to check the back of the fuse box and see if it is the same on the standard cab. If it is should it be as simple as just plugging into it? Sorry for my ignorance here, I really don’t have a very solid understanding of it all works

 

Well the info is just kinda general.
If you decide to get the harness and BECU from the donor AccessCab, it should also be from a 4 cylinder. If it's from a 6, then I suggest you untape the cab harness (donor) and remove wires and connectors not used.
Have you installed the door harness already?

 

I installed everything on the passenger side before I noticed that there was nowhere to plug it in so I pulled it all out again. If it seems like I could just wire it upto the existing fuse box and make it work without pulling the donor harness and fuse box I would prefer it that way. I have another person that’s helping me with trying to do this and the route that they suggest is one that a lot of people did with gen 1 Tacoma’s and basically build a stand alone system to control the doors. I like the idea of it, but haven’t figured out if it will work in a gen 2 as is or if the design needs to be altered. I’m also not very good at reading these diagrams and am very unfamiliar with how relays and fuse blocks work.