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Old January 28th, 2011, 10:09
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ehall ehall is offline
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Join Date: Dec 2007
Location: Southern Maryland
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Re: Everything you ever wanted to know about the AW4

Good info Ken, thanks for getting this started. Here's some more data.

1987-1991 had a Power-Comfort switch that caused the TCU to change between two different shift tables. 1992 and later models did not have the switch, and used the Power mode by default.

On my 1991 model, the "Power" mode uses the following shift table:

1st
2nd
3rd
3rd w/ torque lockup
Overdrive (no lockup)

When the Comfort mode is enabled, the table changes slightly, and also occur at lower RPM to produce a smoother shift

1st
2nd
3rd
3rd w/ torque lockup
Overdrive w/ torque lockup

The Power-Comfort switch provides a ground signal to the TCU. Later models still had the pin on the TCU but did not have an exposed switch. I don't know when the last year TCU had the pin.

Almost every year has a different part number for the TCU, which indicates that there were a lot of changes. However the physical connectors did not change and the transmission harness is mostly isolated from the ECU, so they should be mostly interchangeable within the various generations. It would be interesting to know what changes were made.
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