AW4 Swap - Not shifting right

After swaping in a 98 AW4 from a XJ into a 91 MJ, the tranny seems to shift from either 1st directly to 4th, or through all the gears immediately upon stepping on the gas. Reverse works fine.

Notes on the swap:
1. Tranny was originally intended for a 90 XJ and the harness for the tranny was modifed to run the 90 plug ends.
2. Still running 91 TCU.

Please help me rate potential causes / fixes:
1. Install 98 TCU?
2. Check TPS. IS there a difference in TPS's from different years? Possibly bad TPS in the 91 or need a 98 TPS?
3. Screwed up the connectors during the plug swap?
4. Got a bad tranny?


Thanks,
Jay

Yes there is a difference in the 98 and 91 TPS. I ordered a TPS for my 88 (same sas the 91) and they accidentally ordered a 98 and it was different. Of course if you're using the 91 tcu and tps there shouldn't be a problem as far as I know.

When mine was doing this exact thing it was because my #2 solenoid was open. Might check the solenoids at the tcu.

Look here to find out how to do it... http://www.transonline.com/transdigest/magazines/1997-10/Shift Pointers/index.html

I take that back, I think they changed the TPS on the HO models from the non HO like the 88. Sorry for the mix up.

Still check out the site. Has alot of good info.

The 98 also has an additional sensor that the early harness has no wiring for!!

Really Late reply to this, but here's the issue (swapped a 1999 AW4 with 1994 TCU in my TJ).

The output speed sensor is a really different type on the newer AW4s. A 4 pulse per revolution Hall effect sensor. It actually creates a little voltage for each pulse.

The older "1 speed sensor" AW4s use a magnetic switch at 1 pulse per rev. The speed sensor from the newer (1998+) really confuse the older TCUs.

If you still have the old tranny, just pull the tail housing off swap the rotors, housings, and sensors around and it should start shifting normal.

Jason