Possible ABS problem?? 99 Suburban

[rquack]

I own a '99 Suburban, 105K, C1500, 4x4. The problem occurs when I'm going very slow and have been "riding" the brake for a few seconds. I notice a faint abs noise and then the brakes fail. In order to stop, I must REALLY stand on the pedal. Again, no problems stopping from high speed during normal driving, just when I have had to ride the brake for a few moments: then a loss of braking occurs. If I feel it happen, I can remove my foot from the brake for a second or two and then I'll have brakes again until the problem manifests itself once again.

Is this a defective abs sensor? If so, is it integrated into the front wheel bearing assembly? Or is there a different problem?? Thanks for your assistance.

[gremlin96]

http://www.automotiveforums.com/vbul...&highlight=abs

this thread should help you. just read it all. you have the same brake setup as the other chevys

[snshddog]

Every time that description comes in the shop here it is a master cylinder.

[gremlin96]

Originally Posted by snshddog

Every time that description comes in the shop here it is a master cylinder.

this problem is well known. just type in abs in the search on the chevy fourms and you will get over a thousand hits. i am shocked that car company even tyed a abs system on there cars and trucks. in the trucking industry abs systems are a joke.

[MT-2500]

There is some TSB's out about rust build up on front wheel speed sensors>

[j cAT]

Originally Posted by rquack

I own a '99 Suburban, 105K, C1500, 4x4. The problem occurs when I'm going very slow and have been "riding" the brake for a few seconds. I notice a faint abs noise and then the brakes fail. In order to stop, I must REALLY stand on the pedal. Again, no problems stopping from high speed during normal driving, just when I have had to ride the brake for a few moments: then a loss of braking occurs. If I feel it happen, I can remove my foot from the brake for a second or two and then I'll have brakes again until the problem manifests itself once again.

Is this a defective abs sensor? If so, is it integrated into the front wheel bearing assembly? Or is there a different problem?? Thanks for your assistance.

this is usually the front abs wheel sensors being either pushed out of position by rust OR the wheel bearing is coming apart.


remove the sensors inspect for rust under the mounting surface using a file remove rust . the inside of the sensor hole is blue grease. if the grease is red/rust colored and rust is on the sensor pick up end this bearing is defective.

spinning the hub by hand you can measure the sensor out put. IT MUST be more than 350 millivolts or .35volts AC..a good sensor on a new hub will read about .5 volts/ 500 mv AC..................


when braking at 5 mph the sensor voltage drops. this then activates the abs into operation..

[danielsatur]

There's alot of wear, tear, and heat on those front wheel speed sensors.
80% of breaking is on the front Breaks.

[snshddog]

Like I said, here it seems to always be a master but a ABS sensor is right in line with that too. Easiest I can think of is to pull the ABS fuse and test drive. If it doesn't do it then it is an ABS problem.

[j cAT]

Originally Posted by danielsatur

There's alot of wear, tear, and heat on those front wheel speed sensors.
80% of breaking is on the frnot Breaks.

the sensors are very cheap crap but its the rust and hubs that fail.

sensor wires can be damaged as well...

[j cAT]

Originally Posted by snshddog

Like I said, here it seems to always be a master but a ABS sensor is right in line with that too. Easiest I can think of is to pull the ABS fuse and test drive. If it doesn't do it then it is an ABS problem.

pedal to floor is master cylinder at any speed at all times/ hard pedal booster vacuum is gone / bad brake booster...

no braking at slow speed is ABS sensors/module/hub etc...braking on bad road with too much air in tires will give this effect...

this is something I have handled many times with this braking system ..