Toyota Repair: brakes on 2000 Camry

Question
Hello Mr. Ritter!

Recently I went to the mechanic complaining about an occasional grinding sound and sense that the brakes were occasionally not holding well.  Sometimes I could feel a quick pushback on the pedal.  He checked and found that one area of the brakes (an area that had not been obvious on visual inspection I had asked for a month or 2 earlier when I suspected a problem) had worn down and even damaged the rotor enough for both brakes and rotor to need replacement.

When new brakes/rotor were first put in, the brakes felt VERY spongy (scarily so) when I would first start driving in the morning, though they would get more responsive after I drove for a while.  Also, I am finding that frequently, during soft, slow braking, I feel pushback on the pedal and hear a noise as though the ABS is kicking in.  It feels like something is "catching" during the braking, a hiccup,or like something is not holding right.  This had happened for a short while even before I got the new brakes--but now it's considerably more frequent.   

The mechanic has no idea why this could be happening.  Do you have a clue, based on the symptoms, of what I should ask him to check for?  Could any damage that happened as a result of the undiagnosed worn down brakes be causing these symptoms?

Thank you in advance for weighing in with your expanse of Toyota knowledge.

Answer
It sounds like the ABS is being actuated, possible problems could be a bad abs sensor or metal shavings on the sensor or the wheel speed reluctor rings, these can be inspected by removing the sensors and cleaning the sensors and inspecting and cleaning the wheel speed reluctor wheels, it's also possible that one of the speed sensors has an intermittent condition, this can be checked using a diagnostic tool connected to the vehicle computer and checking for abs diagnostic codes and live speed sensor data while driving.