[b3lha]

Originally Posted by svxistentialist

Nomake

We know from how they behave that there are at least two types of TCU. For simplicity I will call them the Euro type and the Japanese type.

The Euro type covers those markets that get the full-time [as in not rear assist] 4wd gearbox, same as the Japanese get. What is common to these markets is the fact that the TCU software inside delivers power mode on demand only, and also both speed sensors are in the gearbox.

The Japanese type has a different type of speed sensor 1, which is driven by the differential on front. This is the same input method as on your US system also. The fact that your US gearbox uses the same speed sensor 1 circuitry as the Japanese box may indicate that your software inside your TCU is similar to that of the native Japanese box. There is no guarantee it is the same, just hard to figure why they would bother to make two types of software, when one would work just as well for both markets.


US TCU control wiring

I believe, from looking at photos, that all the TCUs are the same in terms of hardware. But I think that the Euro, JDM and USDM markets all got different software. The Euro box is a VTD unit with both speed sensors in the gearbox. The USDM box is a transfer-clutch unit with one speed sensor in the diff and one in the gearbox. The JDM box has the Euro-style VTD with the US-style speed sensors. There is probably another software for the USA FWD cars. That's four different versions of the software.

But they didn't write each version from scratch. I'll bet they started with a base software for a Legacy and tweaked it for the SVX and then tweaked it some more for each market. I would expect to see a lot of similarities between the different versions.

Originally Posted by svxistentialist

Hold a minute; Phil, can you please recheck your notes of when you traced the JDM control wire for grounding Pin 4? The plugs into the TCU are black, not yellow. Yellow connectors go to the ECU

Pin 4 of B59, a 22 pin yellow connector plugs into the ECU. If this is the control pin, then it is controlling it [power mode] through the ECU.

I had thought you might be talking about pin 4 of B66, which is a 20 pin black connector plugging into the TCU. Pin 4 of this block is also not in use on the US control circuit, see the pdf above.

Sorry. You're right Joe. As you said, I meant Pin 4 of B66 of the TCU. Glad you're checking on me. I've been reading assembler code too long and my brain is fried.
It's wired like the Aussie/Euro version, except change the word "economy" to "power" and chop off the circle-A connection that triggers the Econ light. Sorry for leading you astray, Nomake.

http://www.subaru-svx.net/photos/files/oab_au/13732.jpg