This is not your ECM but just an example.
Look inside your compartment below the driver outside. The ECM is probably within 6 feet of the transmission shifter panel. I am no expert here. I had to replace mine and that is why I know where it is.
In worst case you can pull the shifter panel out or however you can get to the wires and try to find any leads that might be the power supply wire.
Using a signal tracer you can inject a tone and then use a sniffer to chase down those illusive wires and fuses.
IF you have a fuse panel below the driver in the outside compartment look very close at those fuses. I prefer to use a test light to touch each side of the fuses.
Myron & Deborah
08 HR Endeavor 40 SKQ
400 Isl, 400 HP/// Now 450 HP
2016 Ford F150 Limited V6 with Ready Brake