[Huskymaniac]

Originally Posted by icingdeath88

If you really want to find some wiring diagrams, this batch of files is a good place to start looking: http://www.subaru-svx.net/forum/showthread.php?t=60472

Those files are for a 1994 (OBD1) car, correct? I need OBD2 wiring diagrams. There are the files from that Russian source. It appears as though MOST of those files are accurate. The ONE exception I have found is the wiring diagram for the TCU. Figures.

But, based on the other diagrams, primarily the ECU ones, I am 99% confident that I was right on my original assumption of the "diagnostic" pins. Connector 55 pin 12 of the OBD2 TCU goes to the ATF temp light and connector 55 pin 11 of the OBD2 TCU goes to pin 80 on the ECU connector. That means that, if an OBD1 TCU were to be used in an OBD2 car, connector 68 (same as 55) pin 11 would have to be swapped with pin 12 as this was the ATF temp light pin for the OBD1 TCU. Also, connector 68 pin 12 would have be non-connected (or connected to a lamp installed elsewhere for power mode indication) and the appropriate diagnostic waveform would need to be sent to ECU pin 80 through TCU connector 55 pin 11.

For people with a 5MT swap in OBD2 cars, if that correct waveform can be determined and sent to pin 80 on the ECU, the CEL would probably not come on for them either.