Still no luck fixin my transmission fault code. so far, I've performed all the tests described in the sticky Bob Guaff mentioned. found nothing wrong till I got to checking the tcm... I cleaned & adjusted the tps to .30 - 5.0 and verified it's signal @ the tcm by backprobing it. I had to repair the wiring harness where it leaves the chassis and turns toward the trans. ( I caused damage to the red, blue and white wires that signal the output shaft speed sensor when I moved the wiring harness and it contacted the drive shaft ) I confirmed continuity of the repair but cannot check for the pulsed signal return to the tcm without an oscilescope. since the odometer remains unchanged, I assume when I shorted the wires, it may have destroyed the output shaft speed sensor? How would I change this part?
Here's something really weird.. I was back probe testing the tcm, found a couple of readings that didn't jive with the wiring diagram I got from Bob. I decided to zero in on pin 19.. the yel / red wire that feed power out of the tcm , thru the harness & to the trans servos. .4 volts.. should be 12 v . checked it multiple times with the three ( 2 wrecking yard + 1 orig ) tcm,s I have. I even cut the wire & bypassed the tcm, ran 12 v to it and checked the signal at the trans harness connector to verify continuity. One time,,,I am checking pin 19 out from the tcm to find a 12v signal and verify I have a working tcm...I get a scramble on my multi meter ??? I jack it up from 20v to 200 volts and BAM! 32 volts! What? 32 v? Got the reading only once... Is there
a transformer somewhere I don't know about? Anyway, I think I'd better start with the output shaft speed sensor? Sure like to know if I'm crazy or there is an explanation for the 32v? Someone help, I,m losin my mind.

 

I haven't tackled that one yet, wish I could help. Be patient, you will get it. Search away within the XJ40 section, others will add their suggestions as time goes on. I wish you the best. Do you have the haynes manual?

 

TNX for the encouragement! BTW sleepycat, I changed the o2 sensor... no effect on limp mode. I don't know how to pm bob gauff... I hope he will advise me further on this.
I wonder if I have a functioning tcm? that may be why the odometer doesn't register new miles ( no signal to output shaft speed sensor and no 12v out of pin 19 ) or it's the other way around ? I have three tcm's... I suppose it's possible they are all bad... Anyone have an ideas?

 

I am going to give this a shot. By TCM do you mean TPS? Throttle position sensor? The module with the red base? This is attached to the bottom of the throttle body.

 

No.,. I mean the trans control module. I have tested the tps and it tests within spec. tnx

 

Ok. You may have tested the TPS and it works. If it is not installed properly, re-installed it will put you in limp. I mean in its correct starting position. Those 2 Allen bolts need to be loosened and turned a millimeter at a time. You will have to reset the the CE light each time you make an adjustment.