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Old 05-28-2007, 03:30 PM
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Originally Posted by Nomake Wan

I'm just curious... wondering if duplicating the signal of the power switch on a USDM car would even work. I know we don't have a switch, but maybe we'll get lucky and our TCU will still accept the signal...

Hmm. Excellent work, though. It's been very cool watching you figure these things out. Hopefully we'll get EDM and USDM applications once you're done fiddling with your Japanese car, hahaha.

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

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.

We need to know which one is earthed by your JDM console switch before we proceed with any experimentation.

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