1998 Lexus LS 400 V8 Two Wheel Drive Automatic 83,454 miles
My lexus is making a thumping sound when accelerating. We have replaced the differential and the problem still persists. We lifted the car on a vehicle lift and accelerated and noticed the rear wheels were turning intermittently. Upon further inspection we noticed the brakes were locking up and releasing and locking up again. We removed the ABS relay and ABS Solenoid relay and the wheels started turning freely again. The problem is we do not know what is causing this and removing the relays has not solved the problem completely as when we accelerate on the ground the thumping still continues off and on and the car seems to be dragging or feels heavy. Can you help me?
Have you as yet done a diagnostic scan as not all faults will set a MIL, do this or let me know if it has already been done and report any codes found, start here.
August, 30, 2010 AT 1:15 PM
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.
August, 30, 2010 AT 11:51 PM
I would be considering having the centre bearing checked, as well as end couplings, I do not feel that it is a speed sensor, I would expect a code to come up if a sensor was actually causing this problem.