did the AW4 change any?

I'm thinking about putting a 99 AW4 into my 91 beater. The car electronics changed in that time period, first with a big jump to OBDII in 96, and then another change in 99 (I think) where the tranny control was moved out of the dedicated TCU into the PCM.

However the AW4 is controlled externally in both cases, so I'm guessing that the computer which manages the shift points was changed, but nothing in the AW4 itself was necessarily changed. However that does not mean that the tranny was not changed anyway...

Can anybody confirm? Can I put a 99 tranny in my 91 beater without worry?

Thanks

I'm gonna take the '99 4.0 it's attached to if I get it.

The electronics changed in 96. The wiring harness is significantly different.

I know, I am trying to figure out if my existing harness will work

The engine is no problem except for the temperature gauge sender. I am trying to figure out if a newer AW4 will work with my old TCU.

ehall said:

I know, I am trying to figure out if my existing harness will work

The engine is no problem except for the temperature gauge sender. I am trying to figure out if a newer AW4 will work with my old TCU.

Click to expand...

There were a handful of changes. In 98, the rear speed sensor changed from 1-pulse/rev to 4-pulses/rev and a front input speed sensor was added. It is possible to use the 99 AW4, but you'll need to pull the tailcone off and swap the rotor for the rear speed sensor and use older sensor. The wiring harness connector from the tranny changed as well, but the harness is easy to swap if you drop the pan. The older NSS can be used. The 99 NSS is identical except for the connector.

Also, the output shaft spline count changed from 21 to 23, and 4th gear ratio changed from 0.705 to 0.75 when the HO engine as introduced.

Thanks lawsoncl. Looks like it should be pretty simple.