Hey ThirdGen! I have a relatively simple question. I recently purchased a FAST XFI ECM and am happy to report i am almost completely finished the project. However one thing remains. I need to simply find (on the fuse box) the proper source that is hot while key in the run position and engine on at all times to power the ECM. I am capable of testing each circuit with a test light but i was wondering if anyone recommends a particular circuit with a certain amount of amperage. Any and all help is greatly appreciated as I am excited and anxious to finally get the car running after sitting for a full year...

 

Id use the ECM fuse since its designed to run an ECM. I dont know if its switched or not, but Im inclined to think its a constant 12v.

 

Thanx for the advice. Makes sense heh heh. Jus dont know if i can make a complete circuit with the old ECM removed...I will check with a test light. Does anyone know if the fuel pump is an active key on position and engine running circuit as well???

 

The fuel pump should be on its own relay under the hood, as long as the key is on the relay gets power to the trigger wire, and the fuel pump runs. It also has a "fail safe" circuit built into it that uses oil pressure. The oil pressure sensor has 3 wires, one runs the gauge, the other 2 are for the fuel pump. When the pressure sensor gets more than 4PSI, it closes the circuit also sending 12v to the pump. Its incase the fuel pump relay fails while driving, the car sees the engine is still running, and keeps the fuel pump running.

 

I see. Thanx for the advice. I will post some pics of the car after im all finished up. Hopefully my XFI tuning cd shows up tommorow so i can figure out how to plot a map sensor and fuel enrichment charts for the supercharger.