After driving around for a few months , decided to do oil change and look things over. Found this arm loose. Reached up to reattach and it just fell off in my hands.
What does this do and do I need it ? and If so where can I get a replacement ?

 

Ride height sensor. You need that! It looks like yours is disconnected. Why?

 

If you have ALS headlights, that is DEFINITELY required for those. Plus for the ride height.

 

Guys… I thought it was an integral part of the CATS system, too… but I am unable to find the description in the workshop manual.

 

The 2010 onward use the ride height sensors in addition to the accelerator sensors. 07-09 only use the acceleration sensors fed to the control module.

 

found it that way. both ends of the link are wiped out, need a new one .

 

begs the question, what else was disconnected for you? Can’t imagine you will need to purchase a new one. Wreckers? Go in armed with the msrp and be prepared to negotiate from 30% of that.

 

Assuming you have AHS, you should have gotten a headlight aim failure indicator on your dash. When my '07 XK front height sensor was running in the wrong position, there was definitely that damn blinking indicator -- but only after I ran the headlight calibration routine with incorrect ride sensor height. I'd bet if you ran the SSD calibration, you'd suddenly get the blinking light. Or, it might be that without the arm, the AHS system just thinks the sensors are constantly at midpoint -- but that would be weird engineering.

To another comment, on the 07-09, as I read the manual, the XK dampers don't have a ride height adjustment, only a two-stage stiffness one. Not sure if the 07-09 XKR had variable damping, but both certainly had it on 10+ units.