I have a 96 xjr that has been giving me grief. After a lot of hunting I have found some previous owner issues. Water had leaked into the wiring harness thru a rusty firewall and ran right down into the ECM. Wires had been cut in the harness and soldered directly into the ECM.

Long story short, is a na ECM different than a sc ECM?

 

Apparently, yes. See some of XJRengineer's threads about ecu chip replacement. I am positive that the mapping is different in the SC unit, but I do not understand why the PROMS could not be moved from the SC to NA units. However, as I understood Andy's answer, he believed that would not work.

 

We just had this discussion a few weeks ago and I posted a reference to the TSB for the recall R/T493.

It explains the 7 different updated PROMS for the EGR fitted X300 models.

The PROMS are what determine the ECM part number and application.

Download and follow the PROM replacement in the TSB to swap your SC PROMs to ANY X300 ECM.

bob gauff

 

Thanks bob. That's what I would have expected, but it is different from what I understood Andy to say. I would bet you are correct!

 

Thanks to all!! It's so great having all your knowledge at our fingertip!!