[b3lha]

Originally Posted by svxistentialist

Phil

I'm no guru, but I'll offer an opinion.

Using the positions of the sensors in the AWD gearbox it's not possible for the FWD transmission to have two speed sensors, nor should they be necessary.

In the VTD type box, VSS1 is always plugged into the actual rear output shaft outside the gearbox measuring the rotation of the rear prop shaft.

There are two types of VSS2. One type lives inside the gearbox for Australian and UK type VTD boxes. The second type reads off the differential output and this type is used in the JDM type VTD and also in the USA type ACT4.

So what I'm suggesting is that because the FWD type gearbox does not have the rear output housing there is no obvious place for the VSS1 sensor to take readings.

In turn this implies that the TCU for the FWD type is different, or at least is programmed differently to account for the fact that only one axle is driven.

This is probably what you would like someone to confirm. It would be best answered by somebody in possession of a full '94 or '95 USA Work Shop Manual. Above is just my best guess.

Joe

Thanks for the opinion Joe,
Not having seen a FWD gearbox, I wasn't sure which bits were missing. I knew that VSS1 measured the speed of some shaft but I wasn't sure that it was actually the rear prop shaft itself.

Ron recently sent me a FWD TCU to look at. I've just disassembled it uploaded the files to my website. Interestingly, the shift maps are identical to the AWD TCU even though the diff ratio is different. So the lower ratio FWD car will change at the same road speed, but the rpm will be slightly higher. So maybe the FWD car feels a little sportier to drive.

You are right that the programming is different, I haven't studied it yet, but I think it's just the AWD-related stuff has been omitted rather than any major algorithm differences. Comparing this ROM against the AWD ROM helps determine which bits of the program relate to the AWD function (because they are missing in this one!).

The FWD circuit board is different too, the components necessary for solenoid C control are missing. So a AWD TCU could probably be reprogrammed to control a FWD box, but not the other way around.

Phil.