Hypothesis ... If i swapped the solenoids from the 04 versions that are installed to the 05 solenoids, would it work? The 05 TCU/ECU knows how to talk to those, and I believe the gearing is the same as both are turbo trannys. Just wondering about what the actual difference is between the 04/05 4EAT since the VBs are both V2P2... Thoughts welcome.

 

I reached out to the wire harness company iWire as i still havent been able to resolve the issue. they replied back saying:

Thanks for contacting us about this. The 2004 model automatic transmission is different from an electrical standpoint than the 2005, so the TCM sees an issue as a byproduct of this change. 2005 uses a 3-wire speed sensor, while the 2004 uses a 2-wire sensor for the VSS 2. I don't see any solution to this problem other than to replace the transmission with a 2005 (or equivalent) model.

-Brian
Level 3 Tech

So of course I am trying to figure out if there is a solution or a jump i can make with another wire/piggyback signal to finally put this to bed. Is anyone familiar with the TCM wire diags for these two model years and know of any difference?

 

This is becoming more and more of a journal of pain, but I tried swapping in an 04 FXT TCU but nothing changed for me. At this point its looking like I'll need to keep looking for a 2005 trans to put in, but I hope that anyone who is going through the same confusion I am will see the things I've tried and they don't have to spend the money on the same mistakes.

 

@aevanov I’m swapping a trans from an 05 outback to my 04 forester, and I found out that the 04 and the 05 trans have differnt places for the transmission speed sensor, 04 is on right side kind of in the middle and the 05 I’m not entirely sure but I think it’s to the rear diff, but anyways the problem is you can’t just stick a speed sensor in the 05 where the 04 has it, you could screw it in but there’s no gears there to attach the sensor to the transmission. So unfortunately I’m probably gonna have the same issue, I hope that helps you trouble shoot maybe you can see if it’s missing. And hopefully somone can give me some advice too

 

@Subiedoobie123
Your's is a manual, there is no electronics like the auto the OP has

 

So you think it would

this is true I will have to call and see what my options are and see if it would be compatible, but hopefully it will be able to just hook right up to where my old one went

 

Through this I have found there are quite a few changes from 04-05 MY so I would be cautious crossing that gap. The wiring diagrams for the two transmissions look pretty different and the guys at iWire also confirmed what I feared. For me I gave up trying to find a similar compatible AT and found an 05 STI donor a couple days ago that's getting frankensteined into the FXT as soon as my parts get here.

 

Thankyou I’ll make sure to keep an eye out for this.

 

UPDATE: I finished the swap, everything from an 05 STI (drivable) donor went into the FXT, and easily enough (but very time consuming.) I had iWire do the harness to make sure i didnt mess anything up and to retain the DCCD and other bits while still retaining use of all the things in the FXT i enjoy. Everything works absolutely fine, and when i took it on my first drive i once again had no speedo, no cruise, and a P0502 CEL...The donor had no codes and everything worked just fine so its something about the FXT that is doing it. A short, or something is still lingering around but i cant say enough about how awesome iWire has been about helping me sort through the diagnostics. Collectively, i have tried the FSM diagnostic, the roof cable that runs to the VSS, and a few other oddballs I've seen on google that netted positive results. I'll update when i get it figured out (some day) so hopefully someone else doesnt have to feel this pain.

 

SOLVED!! After the full swap from the 2005 STI donor, the iWire harness conversion (Auto to Manual), DCCD addition, and everything else to get the car driving, it stayed in limited power mode with the same code. Brian from iWire helped me diagnose my issue and it ended up being a short between 3 points; the ECU, the VSS, and the cluster. Individually the wires were ohming and volt checking correctly so it was really misleading. it wasnt until Brian recommended i created jumpers to the 3 different connectors and repinned them apart from the car's wiring. Brian sent me a wire that split from the VSS and into the cabin where i repinned the 3 connection points and voila, i had speed indication and the CEL went away, no more limp mode, and full STI goodness. I cant say enough great things about iWire, its customer service that is completely unparalleled. I hope this chain of posts helps someone in the future!

 

Fantastic! Thanks for the update