The first thing to do was study the wiring diagrams for the XJ.  I logged on to the and found the connector page. From here I printed copies of the TCU connector pin out and the two plugs that the trans harnesses plug into. 

      These diagrams include the pin numbers, wire colors and circuit numbers for every connection I needed. I then looked up all of the circuits until I knew what each wire went to.  I then used the TJ manual to see what would be the equivalent and wrote that on too. This really took some time, but it is the part that I enjoyed the most. I usually worked on this while in bed or in front of the TV at night. These pages became indispensable as the project continued.  I’m very glad I did them early on.

      One evening after work, I labeled all of the wires for both the TCU and jeep side of the plugs. I did this with scotch tape and a thin sharpie. Again this made the process a whole lot easier when the time came to using them.

      Once I had the wiring diagrams done and the wiring marked, I had a pretty good idea of what was going on. So I started the disassembly part. This took me about 5 or 6 hours.  Remember I worked on this without help and went at a very leisurely pace.

      I found two “interesting” parts to the disassembly process. The first is the stupid reverse torx bolts that are on top of the bell housing. I found that by using a 3/8 socket I was able to get them off. The second challenge was that even after I had all the bolt off the AX-15, the trans would not budge.  I ended up getting the trans out by placing a chain around the trans, supporting it with the floor-jack, and then attaching a come along to the chain and the tow hitch.  It actually worked very well and controlled.

After all the parts are off behind the engine you will notice that there is a bushing inside the crank flange. That needs to come out. I ended up using a air hammer. I had to split it in tow places before it would come out. NOT FUN! Be careful not to damage the flange at all!



AW-4 Procedures

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XJ Trans over view

TJ Trans auto trans

XJ TCU and Notes

TCU wires labeled

Pilot bearing bushing

Torx bolt 3/8 socket removed it

Pilot bearing bushing in place