ABS comes on when rolling to stop

[karotto]

Hi. I have a 2000 Silverado 1500 4x4 and my brakes work fine until I get to just a few miles per hour at which point the ABS comes on. I have to slam the brakes a few times to get the vehicle to fully stop. Any suggestion to the cause of this problem are much appreciated. Thanks in advance. Karotto

[danielsatur]

Try cleaning your wheel speed sensors, and connectors with CRC electronic cleaner.

[j cAT]

Originally Posted by karotto

Hi. I have a 2000 Silverado 1500 4x4 and my brakes work fine until I get to just a few miles per hour at which point the ABS comes on. I have to slam the brakes a few times to get the vehicle to fully stop. Any suggestion to the cause of this problem are much appreciated. Thanks in advance. Karotto

these vehicles have a recall defect with this issue. your front hub ABS wheel sensors may have been pushed out by rusting metal that the sensor sets on.

remove the front rotors, then with an allen wrench remove the sensor fastener stud. rotate the sensor carefully and gradually pull out...inspect the grease in this hole , if it is rust colored the bearing is bad, the grease should look blue. if the sensor mounting suface is rusted file down the rust until smooth.install sensor ,then with a voltmeter while rotating the hub by hand measure the sensor output . this must be above 380MV ac.

which is about 1/3 of a volt AC....with the new hubs I have installed this voltage is around .5volts ac..much higher ..

this is common knowledge ..my replacement hub with sensor cost 80.00 got at 1A AUTO.

I don't recommend any solvent cleaners on these electrical sensors/wires/connectors...the use of a silicone dielectric grease however does prolong the life and prevents corrosive elements from attacking these componets...

[gremlin96]

try cleaning the brake hub. there are ridges that get rusty and the sensor stops working. also clean the sensor mounting. small amounts of rust lift it and it will not read.

[j cAT]

Originally Posted by karotto

Hi. I have a 2000 Silverado 1500 4x4 and my brakes work fine until I get to just a few miles per hour at which point the ABS comes on. I have to slam the brakes a few times to get the vehicle to fully stop. Any suggestion to the cause of this problem are much appreciated. Thanks in advance. Karotto

gm recall on this with this vehicle

[Dano 00TA]

I'm guessing dirty sensors also. Took mine in for the recall and it did it again after about a year, just did em myself as it's not hard at all.

[karotto]

Thanks for your advice but I don't get it. Either the sensor works or not. How could it work at all speeds but fails below 10 miles per hour. Just doesn't make sense. Thanks

[old_master]

The sensor is working as it was designed. The air gap between the sensor and the tone ring is too large. When the sensors are "pushed" away from the tone ring, the sensor output decreases. The EBCM compares wheel speeds when the brakes are applied. If a sensors output is too low, the EBCM interprets the signal as a loss in traction and activates the ABS.

[j cAT]

Originally Posted by karotto

Thanks for your advice but I don't get it. Either the sensor works or not. How could it work at all speeds but fails below 10 miles per hour. Just doesn't make sense. Thanks

the reason is , you lack an education in electrical training. you don't understand electro magnetism.


for your level of education in this area the explaination is this sensor is a generator/alternator the faster the hub rotates the higher this output.

believe me I've done this on other vehicles much larger than this toy sized truck.

using equipment to measure this in a wave form on a visual display , you can very accurately see how the output amplitude changes, and also the pulse width shape.

sometimes the sensor will fail due to internal winding shorts or opens then this method will reveal drop outs..

with this vehicle this is no secret these ABS sensors are very failure prone due to the poor quality of materials used [very very cheap junk]

when these fail you will smash up your ride .NO BRAKES!

[KaIIen]

Originally Posted by j cAT

with this vehicle this is no secret these ABS sensors are very failure prone due to the poor quality of materials used [very very cheap junk]

when these fail you will smash up your ride .NO BRAKES!

Yup. Google this issue, and you will find TONS of reports/complaints. Some cases where people coming out of a parking lot or side street on a downgrade and can't stop, or other cases where they come on when they shouldn't like on a rough surface.

The latter happened to me on my 03. Guy 2 cars in front of me panic stops to make a left turn (without getting into left turn lane,,,) guy in from of me slams his breaks (Ford Ranger) and then I too slam the brakes. I hit a manhole cover that triggered the ABS. I got towed, while the Ranger needed only a new tailgate. In my case, I found that the sensors are faulty in that simple vibration can trigger them. Like cAT said, GM uses very poor quality materials on an already poor design. Mix bad design and bad materials = an accident waiting to happen.