2005 Lexus LX 470 AHC SYSTEM

A few things could be wrong here. There is a fluid self leveling suspension setup in the lx470. There is a fluid pump under the hood on the passenger side top corner mounted to the firewall, It pumps fluid into the shocks and raises and lowers the vehicle when you push the ride height adjustment button. If the pump is out the vehicle will not raise or lower and the off light will flash. Also it could be that the shocks are leaking and have let all of the fluid out of the system which if left for a period of time unchecked will lead to pump failure. There is a fluid resevoir under the hood on top of the pump it is labled and should be filled between low and high mark with lexus suspension fluid. It could also be that your ride height sensons are out of adjustment or broken. There are two height sensors behind the front tires near the top they can be adjusted with a 10mm wrench and there is one sensor mounted to the drivers side rear four link on top by the rear end. I would not recomend trying to adjust them yourself because they need to be set exactly to match each other or the computer will think somthing is wrong with the vehicles suspension and not function. By the sound of your example I would say that there is no fluid in your shocks and that you are bouncing on the springs only. That would make it buck pretty hard. Good Luck