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Subaru EJ25 SOHC ECU difference for manual or automatic transmission?

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Chr_ Casual Dubber

36 posts · joined Mar 2015 ·

#1024094
Hey guys,
last year, we swapped a Subaru EJ25 SOHC engine from a 2000 Legacy (156 hp) into our 1973 superbeetle.

However, the ECU constantly reports error code 38 "Engine torque control" or "Torque permission signal". When I checked the ECU with OBD2, I found values for "Engine Torque Request", "Torque permission signal" and some more stuff that leads to the conclusion that the ECU is expecting to have a Subaru automatic transmission with the corresponding TCU connected.

I bought another ECU that was confirmed to be out of a car with manual transmission, but after installing it, I got exactly the same behavior and the same error codes as before.
So there are two options:
1. Someone screwed me over and the new ECU is again out of car with automatic transmission
2. The ECUs are actually the same for AT and MT and the transmission mode is set somewhere else...

For the older engines 1996-1999, I found some information about a AT/MT identification pin on the wiring harness, which defines whether the ECU should behave like AT or MT.

Does anybody know, where to find that pin on my ECU (2000 Legacy, EJ25 SOHC 156hp) or if it even exists?

I checked multiple websites for ecu pin-outs or wiring information, including this one:
https://hackedecu.com/ultimate_subaru_pinout

But I did not really find anything useful for the 2000 Legacy...

best,
Chris

mackaymanx Custom Title Time!

1,611 posts · joined Jan 2006 ·

#1024095
Have a look here http://sl-i.net/FORUM/showthread.php?18087-Subaru-Factory-Service-Manuals-(FSM)-Every-Model-USDM-EU


Mediafire would be best as some of the Mega links are dead, so you need Gen 3 1999-2003. Even the Impreza or Forester manuals will show the correct wiring. Look for the EDM/AUDM manuals if you are in Europe.
Quote of the week
"Do I wish to send them to you again, nope, no interest can't be bothered really, to much hassle for little or no return."

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mackaymanx Custom Title Time!

1,611 posts · joined Jan 2006 ·

#1024098
B135(Orange) terminal 25 goes to earth for the manual transmission

Wiring for neutral and starter swaps also polarity for neutral swaps between manual and auto.

When I did my auto loom I stripped the wiring going to the transmission control module and salvaged one of the pins. Then used it in the B135/25 position and wired it to the engine earth.
Quote of the week
"Do I wish to send them to you again, nope, no interest can't be bothered really, to much hassle for little or no return."

[IMG]https://www.vw-mplate.com/mplate2-18600.png[/IMG]

Chr_ Casual Dubber

36 posts · joined Mar 2015 ·

#1024126
Thanks a lot!
Wiring B135 - Pin 25 to ground did the trick.
My ECU is now in "manual mode" and all my error codes are gone.

All the wiring diagrams and pin-out tables I had so far were from AT cars, so the pin was not even listed.
For AT wiring harnesses, there is not even a wire connected to that pin, it is just empty...

Additionally, we had to un-wire the neutral switch B135-26, since the ON/OFF state is switched between AT and MT.
Otherwise, my engine would start reving up as soon as the ECU gets a speed signal...

Best,
Chris

mackaymanx Custom Title Time!

1,611 posts · joined Jan 2006 ·

#1024142
Just remember the neutral and starter swap, if the ECU doesn't see a start signal the revs go crazy. Think it upsets the idle control valve.
Quote of the week
"Do I wish to send them to you again, nope, no interest can't be bothered really, to much hassle for little or no return."

[IMG]https://www.vw-mplate.com/mplate2-18600.png[/IMG]