Cruise Control; Recall and updates

[davewhit]

1989 model. My CC isfunctioning intermittently and crazily. Engage then sudden speed-up, or cut out, or not function then speed-up, in other words no control over it except to switch it off!
My local professional expert states that he cannot work on it as it is as originally fitted and has not had the updates through the Jaguar recall system. he does not know the modifications fitted through hese recalls except for some visual connection changes which mine have not had made. can anyone provide me with the info of the recalls and, more importantly the sequence of modifications.
We all heard the scary stories of cars running away as cruise controls accelerated cars into bus queues etc. and my guy thinks i have a CC likely to do something similar. I do know that i went from 70 to "very fast", very rapidly when i switched it on once and it only disconnected after switching all off and coasting to a stop. Fortunately i was on a stretch of quiet motorway.

[jagcat12]

I have had this problem with both my own and someone elses xjs and both cured by removing the cruise control bellows fitted between the air con compressor and the distributer.this is secured by three bolts at the front lift it clear and be aware that there is a vavuum hose underneath that will detach as you lift it clear.Do not detached the throttle activator wire at rear of unit .
remove the bellows from front and rear plates carefully clean the rubber bellows where it fits around the end plates then run a continuous bead of silicine sealant around the rubber at both ends where the end plates fit then refit the end plates.
make sure the vacuum pipe is re attached underneath and resecure the unit to the car and all will be well.



Dave

[davidr]

I think that the recall was to have a kind of vacuum dump valve fitted that lets off the vacuum when the CC is switched off due to the issues you listed in your post. My 1989 V12 has this modification - I'll happily send you some photos if that would help.

[jagcat12]

mine is a 1990 V12 and as far as I know there is no upgrade fitted but if you send photo will compare with mine.
the symtems you describe are typical of a vacuum leak around the bellows and is a very common fault and the silicone cure is the recommended one.



Dave