Cruise control does not engage. Does anyone know where to start looking to fix this? I suppose it could be something as simple as a fuse, but where? If the fuse is fine, then step two? I'm sure this is not an unknown event in the life of the XK8. Thank you

 

Do you have a check engine light? If so, have the codes read and post the actual numbers back here.

Your '99 XK8 cruise control is managed by the ECM and there are any number of OBDII codes that the first thing on the chart says that the CC is disabled.

I had an issue with the CC button on the center console that was causing an error message. A large number of operations of the switch seemed to clear it.