I had this very same problem after having a bearing replaced on my 2000 LS 400. I had removed the hub and taken it to a local mechanic to press out the old bearing and press in the new one. After re-assembly at approx. 5mph as I slowed in the braking process, the ABS motor would engage. After a couple of hours of consternation and trouble-shooting I figured out what the problem was. It seems that the ABS sensor is so simple to install that you can't do it improperly. Not true ... at least in my case. I took it apart twice trouble shooting and put it back together - no workie. On the 3rd time I got under the car so I could see the "seat" of the sensor. Well ... because of the o-ring on the sensor you have to work it / twist it in to place to get it to seat properly. If you just blindly and push it in then tighten down the mounting bolt, it probably won't seat properly. This was enough to have the ABS mal-function !! Glad to have that one figured out!
Last edited by ChileDawg; 06-11-14 at 12:16 PM.
Reason: Solved a problem that i post questions about and wanted to share the solution