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XJ '97-'01 AW4 TCM data?


NAXJA Forum User
Hi, y'all.

I'd like to do a converter lock project on my '98 XJ 4.0 with AW4. Manual shift is not important in this initial stage of the project. As I read the information found in various Internet searches, I get that manipulation of the AW4's valve #3 / Converter Lock will set off the "Check engine" lamp.

What I'm thinking of is something that eventually will work like BrettM's AWShifter, yet a little more sophisticated. By design, it shall be possible to set converter lock-up speed as the driver desires for highway or cruising between 18mph (30kmh) and 43mph (70kmh). As we all know, the original TCM locks the AW4 above 43mph by design. Brake light signal and TPS-signal is already present at the TCM, so it shall be fairly easy to realize a project that frees the converterlock at braking and re-engages it at light acceleration (+5% to +10% easy opened throttle from idle, timer controlled?). Hard engagment of the throttle like kick-down shall also free up converter lock or keep it from re-activation at low speed in case the free-up condition was braking and the driver again wants to accelerate.

1) Does anybody know what sets off the "Check engine" light when valve #3 is manipulated on the '97-'01 XJ's? (AW4 input/output axle speed sensor signal comparison? CCD Bus data comparison of engine RPM vs. AW4 input shaft speed?). I take it that those who try to manipulate the AW4 valve #3 isolates the valve solenoid from the TCM so that manipulation voltage isn't sent to the TCM valve #3 output pin simultaneously.

2) Is it possible to find information or data on the '97-'01 XJ TCM's internal works and logic anywhere?

3) Is it possible to get hold of the connectors used for the '98-'01 AW4 TCM connectors anywhere? The junk yards aren't too keen on cutting a connector from a complete wiring harness. I need both male and female to make a proper experiment box. If the TCM internal works are proprietary, I need some connectors to make a proper break-out box for reverse engineering.

4) Does any other Chrysler model or any other car use the same TCM (and even the same TCM connectors) as the '98-'01 XJ's?
Better yet, search for BrentM i believe, and check through the threads using the search button, its a PDF and on here somewhere.
OK, I found a link to the AW4 manual in an old thread. The manual is a bit "old", I guess. For the tranny itself it should be OK to any year XJ i guess. But still, the AW4 manual doesn't cover the internal workings of the TCM (or TCU).


The term "TCM" origins from my '00 XJ FSM tranny chapter and probably terminology for the shifter control module in '97-'01. The term "TCU" is probably used for '84-'96. Anyways, this is just two names for the same box.

I'd just love to crack what's lighting up the "Check engine" lamp as I go ahead on this project.