I have a 2011 STI with bolt-ons and a pro-tune. I've not done anything to the car in 4 years, so nothing new would have affected my issue. I was cruising down the road and my car randomly died. My ABS, diff lock (flashing), SI drive light (flashing), R diff temp light, traction control light, oil light, and battery light came on. Engine wouldn't turn over. Took it to a shop and they discovered the "ignition coil" 15amp fuse blew on that relay block under the glovebox. They said from everything they checked they believed the ECM was bad. I wanted to verify, so I went back through and checked what they did and more. Just like everyone else, when I turn the key to the on position it blows that fuse. I checked everywhere(other than under intercooler) that I could see from under or above the car for frayed wires, but no luck. From what I can tell, that fuse is tied into that "main relay" circuit path somehow based on the wire diagram. The diagram shows an "ignition relay" having a direct path to that 15amp fuse that is supposed to be in the same relay block, but there is no relay. The diagram shows the main relay and that ignition relay having the same pinout numbers, so I assume they are tied together somewhere. Got the diagrams from alldatapro. I've tried unplugging O2 sensors, the fuel pump, and anything else in that relay block. I unplugged the main wire harness coming into the engine bay from the passenger side firewall, but the fuse still blew. I removed the main relay and the fuse did not blow, so I bench tested the relay to ensure it was functioning correctly. I could hear the armature close and the continuity test passed. To verify my findings, I briged the relay slot in the block and as soon as I hooked the battery back up, it immediately blew the fuse again, so I feel confident the problem is definitely inside the car. I'm kind of running out of ideas, so I'm going to send my ECM to SIA Electronics, but I have doubts they are going to do much for me after talking to one of their techs since it's a "modified ECM". Does anyone have any thoughts. I apologize for the books but wanted to be thorough in case someone else has had the same problem.
On a side note, it looks like the A/F O2 heater and Unit E/G (whatever that is) piggyback onto that one 15 amp fuse to the left that is not blowing. I added some pictures to help. Also, I can't get my Cobb Accessport to connect to my ECM.