I have a 91 4runner with a 3.0 and an auto trans, I would like to swap in a 3.4 and auto trans from a 96 4runner. by using the motor and trany from the 96, will the only wiring I have to deal with besides the relocation of the battery and power to the fuse box under the hood, be splicing in the dash harness? or am I missing something and there will be other wires I'll have to splice. if it helps, I have the motor and trans with the complete motor harness and ecu out of the 96 along with the rest of the harness from the 96.

 

dont have to splice into the body harness. Other than the wiring the swap is very easy

 

I'm lost, then how do I get the rest of the truck to work, like everything in the dash the power windows and locks and so on. I would like to stay away from swapping out all the wiring in the 91.

 

No, you will have to pull your old 3.0 ECU from under the passenger side kickpanel and replace it with the one from your 3.4. This will require splicing the engine harness into the body harness under the dash. Easiest way is to cut the plugs off the engine side of the 3.0 harness and splicing them into the 3.4 engine harness.

As for the auto, I'd make sure that your transfer case will mate up with it, assuming you're swapping from a 4x4 into a 4x4.

Mine was the existing 5 speed, so I didn't need to worry about any of that. Perhaps those who've done the 3.4 swap with an auto can chime in.