I’m diving into a unique project and hitting a snag with my Subaru ECU. Let me give you the backstory – last year, I decided to inject some serious Japanese muscle into a classic German ride. I transplanted a Subaru EJ25 SOHC engine from a 2000 Legacy into my 1973 VW Beetle. This wasn’t just an engine drop; we’re talking the stock ECU and the necessary components from the original wiring harness to ensure everything played nicely together. Paired with a 5-speed manual gearbox, a lighter flywheel, and a custom exhaust, this Beetle is now putting down a surprising 187 whp on the dyno. The power is incredible and it completely throws people off – a real sleeper!
However, I’ve run into a persistent issue. The ECU keeps throwing error code 38, which points to “Engine torque control” or “Torque permission signal”. Hooking up an OBD2 scanner reveals values for “Engine Torque Request,” “Torque permission signal,” and other related parameters. This leads me to suspect that the ECU is expecting to communicate with a Subaru automatic transmission and its Transmission Control Unit (TCU), which, of course, isn’t present in my Beetle setup.
My first thought was a faulty ECU. I sourced another ECU, supposedly from a manual transmission car, hoping it would solve the problem. Unfortunately, after swapping it in, the exact same error code and behavior persisted. This leaves me with two possibilities: either I was unlucky enough to get another ECU from an automatic transmission car, or the ECUs are actually the same for both AT and MT models, and the transmission mode is configured elsewhere.
For earlier Subaru engines, specifically the 1996-1999 models, I’ve come across information suggesting an “AT/MT identification pin” on the wiring harness. This pin is said to tell the ECU whether to operate in automatic or manual transmission mode. This is exactly the kind of information I need for my 2000 Legacy EJ25 SOHC engine (which is very similar to the 2001 model year).
Does anyone know if this “AT/MT identification pin” exists on the ECU for my 2000 (or 2001, as they are very close) Legacy with the EJ25 SOHC engine? And if so, where can I find it? I’ve been searching online for ECU pin-outs and wiring diagrams, including resources like the Hacked ECU pinout database and various forums, but haven’t found anything definitive specifically for the 2000-2001 Legacy 2.5 SOHC OBD2 system.
If anyone has a 2001 Subaru Legacy 2.5 Sohc Obd2 Pin Out diagram, or any insight into how to resolve this AT/MT identification issue and clear error code 38, your help would be greatly appreciated! I’m eager to get this Beetle project running perfectly.
