Originally Posted by PHATsuby
The reason the 5mt ECU won't work is because it has different trigger info. The crank teeth on a 5mt BE is the same as a wrx actually, so if you want it to work with that ecu you will need to change the crankshaft sprocket and the camshaft sprocket I believe as well. Your car is a 6 tooth crank and 7 tooth cam, the 5mt is something like a 40 tooth crank and 2 tooth cam I believe.
What I did I think was just kept my TCU plugged in, one plug was plugged in and the other was not(don't recall which one). I constantly had a CEL though but I could drive the car fine.
What sucks is you already had the motor out to do the timing belt...but if I were to do it over I'd prob want to swap those parts and run a 5mt ecu.
Hope that helps some.
Ben, how on earth did you know that? I've been scouring the entire service manual library and have yet to come across anything that definitively says whether the programming
in the two ECU's is different, let alone different triggers and other hardware. I've found plenty of references to the "ground a pin, now it's manual" trick on the internet, but none have been confirmed on the third gen, just second, and my service manuals don't mention a pin that serves that function. I do have a T30 with Subaru Select Monitor 3 and a TTL interface cable which supposedly will work for coding but not diagnostics. Do you suspect it's possible to change the "coding" on the ECU without changing the "programming"? I'm used to BMWs, which consider coding to be things like "am I a manual?", "What lights are DRLs?" and programming is the lower-level stuff like "what triggers do I use" and "what's my fuel map?", so I'm hoping there might be a way to code what we need into the ECU.