1998 Lexus LS 400 brakes locking

Mark,

Thanks for the advice, it appears that we had the VCS on when we lifted the car and accelerated it which caused it to want to control the "slipping", once we turned the vcs off the wheels turned normally. I read a great deal about wheel speed sensors and upon removing them the 2 front ones had grease on the optical lens and the rear ones had a big layer of dirt and grease covering the lens. I cleaned them with degreaser and a terry cloth and reinstalled them. I drove the car and it reduced greatly the knocking and shaking of the vehicle. The problem is that now the transmission is not shifting properly. Do you think the sensors are bad and need replacing? I lifted the car and accelerated it and noticed that it appeared to be thumping around the transmission or center of the driveshaft, do you think the sensors are causing this or does the center drveshaft bearing need replacing because I still feel some thumping off and on during driving but like I mentioned it is not as bad as before.

Alex