ABS light coming on on 2001 Mercury Sable

For the past few months my ABS light has been coming on almost immediately after i start driving. But before it does it's as if my brake pedal is kicking back at me while trying to break. The moment the ABS light turns on - it stops. I recently changed my break pads and rotors so i know that's not the problem. Could it be the ABS sensor going bad? Any advice would be greatly appreciated. Thanks!

Asked by for the 2001 Mercury Sable
Did the problem begin right after the brake repairs you made?

It sounds as if there is a faulty sensor reading "0" mph when the others are registering higher. This can be due to a faulty sensor, a bad sensor indicator ring (found on the front axles for the fronts..found on the hub on the rears...), a clearance issue between one of the sensors and its indicator ring, or a wiring issue.

Whatever is happening happens every time, so it should be easier to discover. Good luck.
No it happened before I made the repairs. It's been pretty consistent actually. Any idea on how i can figure out which or all sensors are going bad? I went to Advanced Auto Parts to use the code reader but no codes came up. It doesn't read brake codes apparently. Thanks for your help.
The only physical inspections you can do is to look at each sensor and the corresponding indicator ring and determine if there is anything looking out of place. For example, you may find a loose indicator ring on an axle or hub, or a sensor where the wire is pinched. You may find that the clearance between the sensor and ring on one side is greater than the clearance between the sensor and ring on the other side. Other than that, the code reader and looking at wheel speeds at each sensor while driving on the diagnostic tool is the only way to go.
Thanks for your help.