rear suspension sinks ?

You don't say what kind of car it is but on certain cars and trucks there is a sensor that tells the air ride system how fast the car is going or standing still and lowers it closer to the road changing ride performance. On trucks with towing packages the sensor picks up the highth of the truck when it's carying a load or is pulling a trailer and pumps up the air ride back up to level the load. This is caused by a faulty sensor or sensor wire conections or a air pump relay malfuntion.

thomasedwin
April 2013