AW4 trans wiring OBD I - OBD II

I'm swapping a 1998 AW4 tranny into my 1996. There is a difference in the wiring harness between the two, so I am swapping the harness over. On the driver side of the tranny towards the rear there is a plug with three wires that go down into the tranny. When you remove the plug there are still three wires going down into the hole that are connected to something. It looks like they could be accessed by removing the pan. Anyone know what these are for and how I can remove them so they can be swapped over ? ? ?

They are connected to the 3 shift solenoids. If you pull the pan and the filter, you can unplug the wires from the inside and pull them back out the hole.

You may also have another sensor related issue to deal with. In 1996/7, with the switch to ODBII, a front shaft speed sensor was added to the AW4 and the rear speed sensor changed design and number of pulses/revolution. The rear sensor changed from a magnetic type switch giving one closure per revolution to an inductive pickup with 4 pulses per revolution. The older sensor is longer and will not fit into the newer tranny unless you swap the rotor that is pressed onto the rear output shaft.

Does your 98 tranny have a sensor on the drivers side just aft of the bellhousing that the 96 does not? If that's the case, you will need to either use the 1998 TCU or pull the rear of the trannies and swap the rear speed sensor and rotor. The FSM shows how to get at the rotor and pull it off the end of the output shaft. If you go with the 1996 TCU and swap the rotor/shaft you can just leave the front sensor unhooked.

Oh, the NSS is identical between the years, but I believe the connector on that changed as well. Just use your old one.

There is a sensor in the very rear that is the same on both trannies. I'ts just a plastic rod and both look the same. The only real difference I could find on the front is where a sensor looks at the flexplate. It is on the new tranny but not on the old one. On my old tranny there was just a plastic plug in that hole. If I swap my old harness into the new tranny wont the old TCU be able to run correctly with the information it is being supplied? Ohh and the NSS does look the same but has a different plug. Unfortunately I broke the old one so I'm selling the new one to buy another old style so I can swap it over.

If the rear sensors look the same and are the same length, I think you might be okay. If you pull out the rear sensor and turn the output shaft by hand, can you look through the hole and see if there are one lobe or four on the rotor? If you keep the older TCU, you can ignore the extra front sensor as the older TCU doesn't have an iput for it.

I ran into this issue putting a 99 AW4 into a 89 MJ. My first clue that something wasn't right was the tranny upshifting at 1000 rpm since it thought the output shaft was going 4x what it really was.

Yeah that rear sensor looked identical. I can see where you would have a problem in your case. . .. Thanks for sharing your experiance.