weird brakes

[icefishingnut58]

I have a 2001 silverado 5.7 extended cab 4 wheel drive. Ive been having some wired brake problem. I thought it was anti lock brakes until it did it on clear pavement no ice. I will put the brake on and it makes like a wierd noise while im pushing on the brake. and I can feel the brake pedal vibrating. feels and sounds exactly like anti lock brakes on ice. and when this happens if feels like the truck is not going to stop. and it seems to happen only when i step on the brakes in town not when im going down the highway. Any idea what this would be?

thanks in advance

gs

[icefishingnut58]

Originally Posted by icefishingnut58

I have a 2001 silverado 5.7 extended cab 4 wheel drive. Ive been having some wired brake problem. I thought it was anti lock brakes until it did it on clear pavement no ice. I will put the brake on and it makes like a wierd noise while im pushing on the brake. and I can feel the brake pedal vibrating. feels and sounds exactly like anti lock brakes on ice. and when this happens if feels like the truck is not going to stop. and it seems to happen only when i step on the brakes in town not when im going down the highway. Any idea what this would be?

thanks in advance

gs

I meant 5.3 L

[j cAT]

Originally Posted by icefishingnut58

I meant 5.3 L

this is the defective front wheel sensor brake issue. the sensors mounted on the front hubs get pushed away from the sensor toothed wheel inside the front wheel bearing hub.the voltage generated gradually decreases as the rust increases. at speeds below 5 MPH this does not produce sufficent voltage for the PCM to read ..then this commands the ABS to come on.

what can also cause this is the front hub bearing is failing. this is creating rust from the bearing to foul the sensor pick up internally. the sensor is a magnet , therefore and rust gets picked up quickly..

I have done all of this and using a voltmeter proved all the reports from the TSB and the failures of others to agree with my findings.

removal of the sensor is step one. If rust is found on the sensor the front hub bearing is bad. the greased used is blue not rusty red !

If the grease is good then file down the mating surface of the bearing/that is rusted install the sensor . when spinning the hub at a good rate by hand you must get 300MV AC or more. if not then the bearing or sensor is some how defective you will require a new hub/sensor assy. they should come as a complete component not separate.

cost is 75-300.oo..I payed 75.oo 2yr warr. dealership 300.oo 1yr. warr.

some use timken 1yr warr. 160.oo............

[icefishingnut58]

is there 2 assemblys? one on each wheel in the front?

[j cAT]

Originally Posted by icefishingnut58

is there 2 assemblys? one on each wheel in the front?

the front sensors 2 ea . must report the same signal for the left/right front wheels. if the pcm gets a different signal the ABS come on.

each hub comes with a matched/tested sensor to produce the correct signal.

[777stickman]

Normally there are 3 ABS sensors. One on each front wheel and one in the tranny, or t-case, for the rear.

You can remove the ABS fuse to see if this stops your issue. However, removing this fuse will totally disable the ABS system!!

[j cAT]

Originally Posted by 777stickman

Normally there are 3 ABS sensors. One on each front wheel and one in the tranny, or t-case, for the rear.

You can remove the ABS fuse to see if this stops your issue. However, removing this fuse will totally disable the ABS system!!

as you well know , the transmission sensor also feeds the speedometer. since the speedometer is not an issue , this is the GM ABS recall failure in most but not always the cause of this low speed abs cause of braking failures.

not a common failure this transmission sensor , but could be if the transmission was repaired.

[icefishingnut58]

Originally Posted by j cAT

this is the defective front wheel sensor brake issue. the sensors mounted on the front hubs get pushed away from the sensor toothed wheel inside the front wheel bearing hub.the voltage generated gradually decreases as the rust increases. at speeds below 5 MPH this does not produce sufficent voltage for the PCM to read ..then this commands the ABS to come on.

what can also cause this is the front hub bearing is failing. this is creating rust from the bearing to foul the sensor pick up internally. the sensor is a magnet , therefore and rust gets picked up quickly..

I have done all of this and using a voltmeter proved all the reports from the TSB and the failures of others to agree with my findings.

removal of the sensor is step one. If rust is found on the sensor the front hub bearing is bad. the greased used is blue not rusty red !

If the grease is good then file down the mating surface of the bearing/that is rusted install the sensor . when spinning the hub at a good rate by hand you must get 300MV AC or more. if not then the bearing or sensor is some how defective you will require a new hub/sensor assy. they should come as a complete component not separate.

cost is 75-300.oo..I payed 75.oo 2yr warr. dealership 300.oo 1yr. warr.

some use timken 1yr warr. 160.oo............

Icat so what you are saying is weather its the hub or the sensor I would need to get both replaced anyway because they dont sell seperatly correct?

[j cAT]

Originally Posted by icefishingnut58

Icat so what you are saying is weather its the hub or the sensor I would need to get both replaced anyway because they dont sell seperatly correct?

the surface of the hub where the sensor sits gets rusted. the very poorly/cheaply made sensor is soft plastic. this rust pushes the sensor up away from the hole that the pickup is in. carefully remove this sensor [do not break cost as much as a complete hub] then file the surface to clean metal . reinstall the sensor and if the internal bearing grease is not rusted it should work. also make sure the wires are not hitting this rotor. the wire holders are also very poorly made.

If the bearing grease is rusted then a new hub comes with a matched sensor... If you buy a sensor only some have had to use shims for proper clearance to the internal toothed gear..the sensor does not fail, but it can be physically damaged.....

[777stickman]

Originally Posted by j cAT

as you well know , the transmission sensor also feeds the speedometer. since the speedometer is not an issue , this is the GM ABS recall failure in most but not always the cause of this low speed abs cause of braking failures.

not a common failure this transmission sensor , but could be if the transmission was repaired.

Just trying to educate the poster on the sensor locations since it seemed he had ?'s on that.

[j cAT]

Originally Posted by 777stickman

Just trying to educate the poster on the sensor locations since it seemed he had ?'s on that.

yes , I understood that . I was concerned he would get involved with the speed sensor in the transmission , and would be at this point in time a test that may / should not be required.

the front sensors and hubs are big problems with these over the 100,ooomi. I know of one owner 80,ooo mi both hubs failed causing the ABS issues that he has.

he best get this corrected fast, because it is very dangerous to operate with this abs failure.

[icefishingnut58]

Originally Posted by j cAT

yes , I understood that . I was concerned he would get involved with the speed sensor in the transmission , and would be at this point in time a test that may / should not be required.

the front sensors and hubs are big problems with these over the 100,ooomi. I know of one owner 80,ooo mi both hubs failed causing the ABS issues that he has.

he best get this corrected fast, because it is very dangerous to operate with this abs failure.

Hello agian Icat- this post from february. I brought the truck in in feb and they said it was a sensor on the front wheel and advised to have both done. so i did. everything worked fine untill now. It is starting to do it agian. can I just take the fuse out and run it without abs system? I would just have normal power brakes right? in the winter I would go back to pumping the brake at quick stops? or what does the abs actually do?

thanks
gs

[icefishingnut58]

Originally Posted by icefishingnut58

Hello agian Icat- this post from february. I brought the truck in in feb and they said it was a sensor on the front wheel and advised to have both done. so i did. everything worked fine untill now. It is starting to do it agian. can I just take the fuse out and run it without abs system? I would just have normal power brakes right? in the winter I would go back to pumping the brake at quick stops? or what does the abs actually do?

thanks
gs

one more thing they changed just the sensors.

[MT-2500]

No No No
ABS brakes are a major saftey device.
They may save your like or the life of others summer or winter.
Rain or slick spots or worn out tires are present winter or summer or fallo or spring.

Pulling ABS fuse should only be done for testing and drive with caution and only long enough for test.

Pumping brake pedal does not make ABS braking.

[MT-2500]

As to what ABS brakes do.
With 4W ABS brakes when you are stoping/braking and one or more wheels stops turning same speed as orhers.
The ABS kicks in a split second's and starts releasing the brake/pressure to the wheels that are not turning as fast as others.
Keeps all wheels at same speed to keep you from sliding - side ways / tail spins /swaping ends and ending up in ditch or in the path of on comming trafic.

Also with traction control the ABS system the ABS aids in keeping drive wheels turning the same speed.