My check engine lights are all on and we put it.

I didn't change the computer yet when I plugged it in the computer no code came up it said check fuses or ecu is bad but everybody I talk to says the computers never go bad in those cars the car always ran fine one day the brake light came on then weeks went by then the engine light came on then traction light came on and after that u had to push the gas peddle to the floor just so it would go

No code came up all it said was can connect check fuse. So then we looked it up in a book and it says that to check the fuse and if the fuse are good then the ECU is Bad. So for the hell of it we try I another computer just to make sure the computer was good and it said the same thing can't connect check fuse. Let me ask u something I can't find a computer with all the same part numbers the one I found is for the same year lexus but the last 3 part numbers are different does that make any different if I put it in will it work?