I own an XJR which I had lost all my keys to. I bought a transponder module and key off eBay to have programmed with my car because the vehicle entered immobilization and needed the original keys to be unlocked. After putting in the used system, I got the vehicle to crank but could not get it running. I had a programmer come but he could not successfully program the trandsponder and the vehicle entered immobilization again.
I bought an XJ8 VDP to use for parts on another project and can pull any and all ignition related components and swap into my XJR. If anybody has any experience with this issue, any advice would be greatly appreciated.

Yea... I would, but.
My dealer estimated me for 2 grand as to change out the ignition system. I replaced them myself with matching serial number parts from eBay. I have had 2 programmers come by both with no avail.

For the keys, $125 cut and programmed from my dealer. Just needed to show registration