On the rear lower left arm there is a small black plastic box with some sort of link/arm attached to it and a wire to somewhere.
Does anyone know what this is? And if I replace the stock arms to adjustable arms what happens to this thing?

Hello, My guess it is a part of the stability control system. A sensor to let the ASC know what the car is doing...

It's the sensor for the auto-leveling headlights. Are you sure it's attached to the lower-left control arm itself? I replaced the lower control arms with adjustable ones on my 2006 and don't recall having to relocate the leveling sensor.

Im pretty sure it is, but I hope Im wrong. I'll be under the car today so I'll know for sure. I do want to replace the lower arms so I hope it is not attached to them.

thanks,

the box is for auto leveling headlights. if your aftermarket control arms don't have an attachment, you can zip tie it (usually instructions even say to do this).

That's strange - now I'm going to have to go out and look at my car tomorrow. I installed H-sport adjustable lower control arms and really don't remember having to to anything with the auto-leveling sensor at all. Of course, if it was something really simple, I might have just done it and forgotten about it.

Factory has the arm attaching to the upper control arm. Dont know why anyones would be different in that regard.

OK, I installed new springs last night and had a good look at that "box", it is attached to the upper arm not the lower. I would have never thought it was for the head lights but anyhow at least it will not be an issue if I replace the lower arms.
thanks for for your help everyone.

The front right suspension arm has the counterpart to that headlight level sensor.

yeah i saw that too. anyone recommend where other than Town fair tire chain, to get an alignment, camber adjustment? is that somethng u can do urself?