I have a 13b-re cosmo rotary in a sand rail and I have the stock wiring harness and stock ecu for the engine. I just need to know where the positive and negative go on the ECU to turn it on. Or does the ECU get power from the wiring harness somewhere... I just need it to turn on is all and i know some of the basic requirements of the harness but i just don't know where the power is coming from. Any help would be great!

 

I am just finishing up my wiring on my 13bt s4 swap (not sure if if the harness will be similar) into corolla, and I have just the emmisions harness, technically the engine harness which has the plugs that go to the ecu and all accessiories on engine. What I found is that the harness powers the ecu.

You should find a yellow 13 pin(i think) plug there are 2 yellow/black wires that are switched power and a white/blue wire that is constant power I think you'll need to supply those with power. That is if you dont have the front harness that it plugs into which I dont.

but this isnt 100% you should double check the FSM, its just what im doing, I will be attempting to start my engine this weekend I can get back to you on it if you like?

 

Thanks! this helps, yeah i also just have the harness with the plugs that go into the ecu, ill take a look this afternoon on my harness. Please let me know how it goes!