Subject: Subaru EJ25 SOHC ECU difference for manual or automatic transmission?
Chr_
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posted on February 27th, 2016 at 09:39 AM
Subaru EJ25 SOHC ECU difference for manual or automatic transmission?
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?
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.
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mackaymanx
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posted on February 27th, 2016 at 12:02 PM
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.
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Chr_
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posted on February 28th, 2016 at 09:39 PM
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
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posted on February 29th, 2016 at 03:07 PM
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.
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posted on February 27th, 2016 at 09:39 AM
