Hi,
My Blazer is a 2002 LS 4 wheel drive 4 door with rear rotors. My brake pedal has a small and very short hesitation with a small and very short rattlely thump at the same time, sounds and feels like a very brief ABS activation when it is pressed. It is not consistant and does it randomly. It also isn't the typical ABS function you get when you first startup and press the pedal some cars will do. It will do it anytime from a short drive to a long drive. It seems to do it on turns more than straights but will still do it on straights. Doesn't seem temperture related. The fuild level is good as well as the pads and calipers are not that old. I do not see any leaks. The fluid hasn't been changed which I do plan on doing but I don't feel that this would be the problem. The pedal still has a nice feel and does not drop to the floor. All joints(*****, rods, etc.) are well lubed without any visiable problems. I can't seem to find the problem and it only stared doing it this year.
Any help would be greatly appreciated
Thanks
Buddy

 

if it does it when you are are going very slow, like 5mph and under there is a problem with rust that builds up between the sensor and the bearing causing a false reading. proper way to find this problem is hook it to a good scanner and watch which wheel craps out when it does the abs pulse and fix that side.

 

Mine does this too. Its usually if im braking and turning(such as going into a turn around). It also does it if im braking a hit a large bump. Scares the crap out of you but its just the ABS kicking in. Northern GM vehicles get it the worst because the salt corrodes the sensors. You can replace them if you want.

 

we hook them up to a data stream with wheel speed and watch which wheel is cutting out when the abs is activating then replace that sensor. sometimes though too it will pull the opposite way. so if your right is activating it will pull to the left when braking indicating its a bad right bearing/sensor

 

I have a Innova 3160. Ive had it for awhile and haven't went thought the manual yet. Does anyone know off the top of their head if this will read the sensors?
Thanks

 

My novia doesn't do any abs test, it can only read and erase the abs dtc's. I recently just got a C0267 code and looked into that, I couldn't repeat the code without making it fail my self by removing the fuse(60A) the 10A I believe is only for communication. The pump and module(ecbm) seem to be working fine as I did a brake test on gravel and the pump/abs works as expected. The internals of the ecbm may be showing signs of bad connections but I am not ready to open it until is shows further signs of malfunction such as the pump not shuting off or turning on or throwing more code.
So I wonder if this could be giving me the brake issues I am having at slow speed or could it still be the sensors and this was just a fluke that the ecbm gave the code.
Typical intermintent crap

 

Is there any way to clean up the rust or is replacing the hub/sensor the only fix?

 

yes and no. the problem is trying to get those sensors out, i think i have about a 50/50 sucess rate of getting them out. in a perfect world you just take the allen held bolt out and the sensor should just pull out of there but the top of the hole develops a rust ring and breaks the sensor when trying to get it out, ive tried working them back and forth while soaking them, soaking them over night, its just hit or miss if you get the sensor our.

you can just get the sensor wire but most the time at work we just replace the entire bearing with the harness due to the bearing only being like 20 bucks more then just the wire. especially if you have a lot of miles the bearing is probably going out anyways,

but yeah if you are successful in getting the sensor out in one piece you just have to get in there with something abrasive and grind it down, i find that a wire wheel usually doesnt do the job as the rust/metal is too thick so i have to actually get in there with a die grinder. just be careful not to take off to much material other wise the sensor will go into the abs ring