I recently got back from a 7 month deployment. About a week after I left my battery died. My wife didn't know that it was the battery so my car just sat in the driveway the whole time. When I got back I replaced the battery and all was good. After driving the car for a few days I noticed when I was braking that something wasn't right it just didn't feel right and with the pedal at about 75% it would kind of pulsate. When I would get out of the car I could smell the brakes on the left front and right rear. I took off the tires and checked all 4 calipers and sure enough those two calipers seized. I replaced all 4 calipers, pads, and bled the system about 5 times. Everything is good now except that pulsating. I have searched and searched and I cannot figure it out. The rotors are fairly new and I checked them using a flat edge so I really don't think that it's a warped rotor. When the engine is off and I press the brake I have an extremely hard pedal so I'm pretty sure the master cylinder is good. When I start the car the brake is smooth and acts normal so I think the booster is good. When I bled the system I started at the master cylinder then the RR, LR, RF, LF and repeated till there wasn't any air making sure to tap the new calipers as I was doing it. Also I used a vacuum bleeder so from what I understand no need to have a ABS scan tool. I never let the fluid in the master cylinder drop below half. When my friend was applying the brakes I could see the calipers and brake lines flexing. I did notice though with the ignition on and the car in park when I press the brake the idle drops, is that normal? I know that the most likely causes for this are the master cylinder has a leak, booster could be bad, or the speed sensor for the ABS is dirty. I just don't want to put anymore money or effort into this issue unless I have a solid lead on what it could be. I'm sorry if that was way to much information but like I said I just really want my brakes to work correctly... It's about to snow.


Pertinent info:
2003 LS 4 door 4 wheel drive ABS 113k miles

 

So I think I got it narrowed down to the speed sensor.... Well I'm about 99% positive. After Searching for a few more hours I came across a thread on here about the speed sensor issues. Went down to the car pulled the fuse for the ABS and tada no more brake issue. Planning on taking the tires off in the upcoming days and fixing it for good.

 

sounds like your rotors are warped.... replace em, im sure that will fix it

if you really want to check the rotors, use a dial indicator... especially if the calipers were seized, those rotors were under extreme heat.... even tho they are newer...they are more than likely bad..

 

'Pulsating'... That's kind of a term for warped Rotors. 'Chatter' would be more descriptive to what a Bad ABS sensor does.

There are metal 'washers' between the sensor and the Hub. Sometimes these rust a bit and force the Sensor up off the Hub just enough to mess you up. Take the Allen screw out, lift the Sensor out watching for these washers ( sometime more then one) Clean the end of the sensor and run this washer on some light grit sandpaper. reassemble
That should fix it.