So yeah I just got failsafe for the first time. Not quite halfway home. Guess I need a code reader now eh?

 

The first time? No code reader?
How long have you had your Jag?

 

Crappy Tire has one for $99 that works for me. Same as Parts Source.

 

If you have an andriod or iPhone try Torque.

Actron readers have worked fine for me

 

I've figured out the trigger. High speed travel on cruise control (say 140kmh+) then hitting the cancel button or travel at speed of 150kmh+ and hitting the the decrease button. Those two actions trigger the warning which shuts the cruise off until the car is restarted.