Hello, the airmatic suspension control module is located in the fuse and relay box, left side of engine compartment. To replace it, the battery should be disconnected. After installation, the module needs to be calibrated using the dealer's STAR diagnosis system.
I have seen both extremes of the spectrum on that one - vehicles with this module replaced driven for weeks without calibration. On the other side of the coin, I have seen vehicles with this module replaced where the vehicle drops to the ground as if it is on hydraulics. Safest bet would be to have it towed to the dealership where it can be calibrated.