I have heard it said that if you replace the ECM with one that even has the exact same part number, that you have to get the ECM reprogrammed due to the immobilizer/key not being recognized.
If this is true, any recommendations for who can do do this.?
Also, doe the immobilizer prevent the car from even turning over on the starter or just prevent it from firing?
Thanks

 

It's more complicated on the 4.2. Even if the part #s match, it will need to be reconfigured. See this thread:
https://www.jaguarforums.com/forum/x...5/#post2494869

IIRC the car won't crank until this is completed, and note this procedure will break the existing ECM's 'relationship' with the car (i.e. you can't just put the old one back)

 

the ECM topics are really scary. And I thought re-soldering the ABS box pins was tricky (naive, huh ?)

I’ll be doubly happy I have a 4.0 if I ever have to go down the ECM replacement road. Knock on wood.

 

not a big deal. program cluster as new, pats id gets transferred car will start, been there done that. if you have comms with the old ECM save its VID block and put it in after