Odd Brake Issues on 2005 Gen II with 140K miles

OK, so I have read all the forum threads I could find on "grabby" brakes and similar issues. My car has 140K miles and has never required any brake work.

It is difficult to describe, at freeway speeds they seem to work fine. Around town, say 45 mph and below, the brakes work as though I'm a 16 year old learning to drive for the first time. I'll press a little, and get nothing, press a little harder and they really grab and the car lurches. But it also seems inconsistent, it doesn't always happen.

Like I said, I read the threads on "grabby" brakes and dutifully cleaned or de-rusted or de-glazed my rotors. In fact I have several long down hills on the way to/from work and I have repeatedly shifted into neutral and used just the hydraulic braking (no regen). This has had NO perceptible impact on the "grabby" braking performance. Further, I would describe the hydraulic only braking as "excellent", they work just fine and I do not get any of the pulsing or weird brake behavior when braking with the car in neutral.

I took it to the local shop and they did an inspection and test drive. Of course, the car drove perfectly when the mechanic drove it. He said the there were no error codes and that everything checked out OK. Still plenty of life left in the pads and the rotors. The only thing he could recommend was cleaning and lubing the calipers and replacing the front pads and resurfacing the rotors so we had a good baseline.

I discussed the "brake stroke sensor" which came up in some of the threads. He called the local dealer, and they said they do not stock the brake stroke sensor and have not sold one in 2 years. Here in Palo Alto, CA, about every other car is a Prius, so while not exactly scientific, the mechanic said that sort of rarity makes it an unlikely contender. He said replacing it would run about $400, so it is not a cheap trouble shooting exercise .

We have had some intermittent rain and it may be somewhat related to moisture, but it is NOT a "rust on the rotors" problem.

Any suggestions for my next trouble shooting steps or a possible root cause??? THANKS!

 

Final Answer: So I tried Patrick's idea (disconnect the battery) because it was too easy not to try... but alas it had no effect.
So I went ahead and had my mechanic do the front brakes (resurface rotors, new pads, lube all moving parts, clean everything) but as I kind of expected.. that didn't do anything either. Still had odd "pulsing" both at low speed (<10 Mph) and higher speeds (35 mph), though the brakes continued to seem fine when ever I shifted into neutral and braked using hydraulic braking only during down hills.

So the mechanic did some research and was advised to adjust the rear brakes/parking brake and bleed the brakes. Though I was highly skeptical and went ahead and had him do both of those... and lo and behold.... the brakes WORK PERFECT now. No idea if is was the brake bleeding or the adjustment that did the trick, but the brakes feel better than they have in years.

Note: Bleeding the brakes is apparently a PITA, don't attempt unless you have access to the Toyota service guides and a 2nd person to help. Perhaps there are some other posts on this forum about bleeding brakes, all I know is that it is not as straightforward as bleeding brakes on a "conventional" car.