Hi . I have the intermittent check Rear Lights, fail safe engine mode error message and cruise control cannot be selected when error message is showing,. problem. Also I find that upon stopping and restarting the engine, the error message is not showing but with cruise control ON if I have to brake then I no longer have cruise control and the error messages re appear. Having read a few threads it seems to me that it may be the brake switch . Could somebody confirm my thoughts please.

 

In most cases, that is indeed a brake pedal switch issue. We see more and more of them as these cars continue to age....

 

Might also check the rear light ground issue. I had the same cruise symptoms, and fixing the ground cured them. Post #25 in the below thread has some good pictures of the issue and the fix.
https://www.jaguarforums.com/forum/x...d-35083/page2/