Error When Attempting to Flash ECU

IT IS FIXED!!!!!

Thanks everyone for the help and suggestions.

I don't know if I am an idiot for not seeing this sooner or if the cause was unforeseeable even by someone who knows what they are doing. Please let me know.

Here is what it was:

So this morning I was going to start testing the ODBII to ECU connections. But before I started I figured I would try a few things first. The desperate things that shouldn't work. In my life I have found this saying sometimes true..... "If you have tried everything that should fix the problem, start trying things that shouldn't fix the problem and it will fix the problem.". So really stupid things like "Can I flash if I close the hood or close the door or leave lights on "Auto" or leave supercharger water pump running". These are things that were common during all attempts and failures.

It was the supercharger water pump. Before I attempted any flash I would go into the engine bay and disconnect the water pump for the SC because when the truck was "ON" but not running the pump would run. To prevent the drain on the battery I would disconnect that. So this pump is piggybacked on another breaker, the one labelled "INJ". Which I assume is for the injectors. I would pull the fuse rather than disconnect the wire. After all what does it matter if the injectors have power during the flash? Well it turns out if that breaker is pulled one will not be able to flash. So I disconnected the wire and left the breaker in. No problems at all. The flash worked perfectly.

So my question is, am I the idiot? Or is this a "That breaker shouldn't have made a difference." situation?

If I am an idiot, how/why do the injectors need power to perform a flash?

Thanks again everyone for the help, I really do appreciate it. If I am an idiot I apologize for wasting your time.

 

That fuse/circuit is the ignition switch input to the ECU. Makes sense now. Glad you were able to figure it out!

 

Matt Wilson said nearly the same thing:

"Well I am glad you found the issue!. That injector fuse also provides all power to the ECU they are ran along the same fuse lines. It isn't just for the injectors. It is a really odd way that toyota labels it."

So I feel I am not 100% an idiot. Maybe only 30% idiot.

I am just happy it was an easy and free fix.

Thank you again for your help with this.