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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 book 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.
Thanks!
 

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Midlde pic. Your problem is after the relay. I cant rule out ECU, but it's not what I would suspect. I'd look at shorted coil-pack wiring - OK - this is an educated guess I really don't know - 12V power supplies one side of each coil. ECU drives them low and "releases" to create spark. So look for a short from the hot side to ground. How? Start by pulling the relay. Use a meter as you did to check the relay. You learned or can learn which contacts when closed feed off the ones shown in blue. "Follow" the one that is shorted.

A short inside a harness is only likely if the harness has been overheated by this or another short issue. So unless you are aware of this having occurred start at any point the might touch something hot - turbo, exhaust, or where friction might occur. After that prepare for a harness repair - or even replacement.

Can you unplug the ECU and jump the relay as you did before to rule it out?
 

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Midlde pic. Your problem is after the relay. I cant rule out ECU, but it's not what I would suspect. I'd look at shorted coil-pack wiring - OK - this is an educated guess I really don't know - 12V power supplies one side of each coil. ECU drives them low and "releases" to create spark. So look for a short from the hot side to ground. How? Start by pulling the relay. Use a meter as you did to check the relay. You learned or can learn which contacts when closed feed off the ones shown in blue. "Follow" the one that is shorted.

A short inside a harness is only likely if the harness has been overheated by this or another short issue. So unless you are aware of this having occurred start at any point the might touch something hot - turbo, exhaust, or where friction might occur. After that prepare for a harness repair - or even replacement.

Can you unplug the ECU and jump the relay as you did before to rule it out?
I was considering seeing if the issue persisted without the ECU plugged in, but wasn't sure if that would mess anything up by applying power without it being hooked up. I assumed it wouldn't since the power will just stop at the end of the plug, but wasn't sure. I looked at the coil packs, but didnt see any of the wires that looked damaged and since it wasn't in the same circuit path as that ignition coil fuse that kept blowing, at least according to the diagram, but I definitely wont rule it out. I may end up just unplugging one at a time to see if it keeps blowing. Thanks for the help!
 

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I looked at the coil packs, but didnt see any of the wires that looked damaged and since it wasn't in the same circuit path as that ignition coil fuse that kept blowing, at least according to the diagram, but I definitely wont rule it out. I may end up just unplugging one at a time to see if it keeps blowing. Thanks for the help!
I was assuming ignition coil fuse would mean it was powering ignition coils? If not, what does it power? Will try to look on Alldata

Looked: on an 05 the ignition relay powers FB19 and includes:

58155
 

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I was assuming ignition coil fuse would mean it was powering ignition coils? If not, what does it power? Will try to look on Alldata

Looked: on an 05 the ignition relay powers FB19 and includes:

View attachment 58155
My apologies, I should have clarified. I meant it wasn't in the path from the testing I conducted. After I disconnected the main wire harness in the engine bay and then tested it, it still popped, so I concluded the short was somewhere inside the car. I was thinking that my thought process may have been wrong after what you said, so I was going to test the coil packs anyway. I went ahead and sent the ECM to SIA Electronics since I wasn't sure if I would get a response or not, but I can at least test if it blows with the ECU not connected now. If they tell me the ECU is fine, I'll be going to the coil packs.
 

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Friend of mine had a very similar issue, it died on the ride to a car meet and would not start. AP didn't work, etc. Fuel pump wouldn't prime.

his SBF5 fuse kept popping every-time he'd turn the key. For him, it was a loose connection on one of his injectors. He only found it because he unplugged all of his injectors and plugged them back in tightly and the problem was fixed.

I know this isn't exactly your issue, but if all the ignition coils are on that one circuit I'd unplug them and see if thats the issue.
 

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Discussion Starter #7
Update
Just received word from SIA Electronics that my ECU appears to be in working condition and does not appear to have a short. I tested to see of the fuse would blow with the ECU removed and it did not. To me, it appears the ECU would be bad, but they are saying it's good. Anyone have any insight on that? Once I get my ECU back i'm gonna try unplugging the ignition coils, but if it's not that I'm at a loss of what to do next. :cautious:
 

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Shorted coilpack or shorted in harness.

The coil pack only has wires? Should not be able to "beep em" from/to gnd.

Added: previously covered
 

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UPDATE
Welp, I'm a dumb founded, but I believe I have a better idea of where I need to trace. I unplugged the coil packs, turned the key and the fuse popped. I wasn't sure if the plug was touching the contacts somewhat because it was the driver side rear coil and it's hard to get to, so I had it pulled out enough where it was resting on the lip of the coil pack female port. To ensure it wasn't connected at all, I pulled it completely out, turned the key, and this time, no pop. Turned the key back to the off position, then turned back on and it popped. I pulled the battery back out to make sure the plugs weren't touching the body or anything metal. Put the battery back in, turned the key, and no pop. Hooked up my access port and I was able to connect this time to my ECM. For the heck of it, I turned the key off and back on. The fuse popped again. Took the battery back out to ensure once again nothing had moved. Put it back in, tried two more times and the fuse popped both times. I'm thinking there is possibly a short somewhere in the coil packs cabling heading back to the main wiring harness on the driver side. That area is obviously really hard to see, so I'll have to get up under it and trace that cable back to the main harness. I suppose it's possible that it could be the main harness from the firewall to the ECM and I was somehow shaking the car when I was leaning against it, but it seems doubtful. The only change I've had through this whole process was taking the battery in and out which was actually causing cables to shift.

More to come.
 

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Sorry for the delay in response. I recently had a baby, so haven't been able to work on the subie. I believe I've eliminated every possibility at this point and I believe the short is behind the dash. I have unplugged every component on that circuit for the "E/G unit" circuit. I originally thought it was the path for the ignition coil, but then realized subaru was being lazy with the labeling once I got my hands on a real wiring diagram. The path is "C1 and D7" coming out of the ECU and goes to the MAF/drain valve before it goes into the relay. Once it comes out of the relay it goes to that 15 amp fuse that keeps blowing, then SBF 7, then source... according to the diagram. I am getting a .06 resistance reading on both C1/D7 (ECM wiring harness) and another white black cable that goes to the starter relay that is in the same bundle as C1, so it must rubbing the bundle behind the dash. I've removed the ECM/main relay and bridged the relay socket and the fuse still blows, so that tells me the ECM is indeed good like SIA said. The problem is definitely on the load side, so I dont know what else it could be other than the bundle being rubbed behind the dash, so a top dash removal is the next step.
 

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R.E.S.O.L.V.E.D
After tracing the individual cabling behind the dash, I saw where the C1 and D7 merged and then went out to MAF, drain valve, etc. The YB that was going to the SBF 7 behind the driver side fender liner was almost cut straight through and a few others were dented or slightly cut. This is a bad design on Subaru. I'm not sure how it didnt short sooner because it was apparent the rubbing had been happening for quite some time judging by how the wires were rusted and as stated earlier almost completely cut through. I even tried to recreate the short by touching the copper to the chassis where it was rubbing, but I couldnt get the low resistance reading i was getting before, so it must have just hit in the right spot (due to it being a painted surface). The cable bundle had vinyl tape and split loom around all of it except for the 2 inch exposed portion that was right up against the sharp metal edge. If you have that same 15amp fuse blowing everytime you put the key to the ON position, be sure to check this location as well as the drain valve, pressure solenoid, and MAF.
20200217_152336.jpg
20200217_152331.jpg
 

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Congrats - that one was some work!!! Thanks for posting too :)

It not a common issue though. I expect there is a reason this occurred on your car.
The hole looks to be sized for the split loom . You don't think it was supposed go through the hole?
 
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