Does anyone have an idea where to start with this problem? I have a 1998 xj 4x4 4.0 w/aw4. The check engine light came on and I pulled the code. On-line its says no bus from tcm (transmission control module). Then I notice the torque converter was not locking up. It will lock up if i put the pedal down farther than usual but then unlock as soon as I try to maintain a constant speed. Is this a bad ground issue? A tps issue? If so, what can I do to check these components? Thank you sincerely!

 

you answered your own question, your trans ctl mod is not comunicating therefore the vehicle is in limp home mode , yes the converter will lock but only when the PROM tells it to. Sadly this is not really a condition your can check without a machine that comunicates with the trans. You can check all powers and grounds out of the computer going to that circut but its a very time consuming job . I would take to a local trans shop and have them check it out.

 

not really all that can be tested right at the plug for the TCU...the three solenoids including TC lock can be ohms tested from this plug rather quickly also.

 

You can check my writeup on locking it manually here "https://www.cherokeeforum.com/showthread.php?t=14114" for a temp fix...Tj