Have 02silverado4x4 when I apply brakes at low speed pedal won't go down and vibrates abs light is on

Could be a rotor. Could be ABS. If it vibrates fast at low speeds or at stopping, It's the ABS. Has to be on a scanner to see witch sensor is acting up.

not necessarily
if you have abs brakes it is the pulsations as the wheels lock and unlock from the abs activity
this transmits as a pulsation under your foot
it may also mean that the discs have warped and the warp is pushing the piston back in then letting the piston out
it is more noticeable at low speed light pressure stops but it depends on the speed
Take the vehicle to an accredited brake shop specialist and get a proper diagnosis done

The ABS system is related to emergency stopping, not normal brake use, where you don't want the tires to lock-up when the brakes are hit very hard. ABS stands for Antilock Brake System. When the ABS light is on, the ABS system is not active. This means the ABS will not be Antilock when you need it. This does not mean you don't have brakes. The brakes you have are normal brakes without the added feature of antilock.

The light is on because a system fault has been detected. Most of the time this is a wheel speed sensor that has failed. Basically the system works by having 4 wheel speed sensors connected to a control unit. The control unit determines how much braking presure each wheel needs according to how much pedal presure you are applying, related to the vehicle speed, and the rotation speed of each wheel. If one wheel is spinning slower than the others that would mean it is locking up (less braking efficientcy) and the control unit then reduces the presure applied to that wheel so it doesn't lock up.

If a wheel speed sensor goes bad the entire system can't function so it shuts down and it is now a regular braking system. This means that it will work and feel fine to you, the operator. But in an emergancy, the ABS will not function and the brakes may lock up which is not as efficient as ABS.

I recommend you get it scanned for codes and find out what is wrong. It is a great safty feature that I think you are better off with, than without.

Some auto parts stores will scan your car for codes for free, like autozone and others. Call around and find that free scan. Then take it to a reputable shop, dealer, or your brother-in-law who is a master mechanic.

Good luck, and be safe!

There's a service bulliten about that problem with rust build-up on the front hubs pushing the sensors out of posistion [ most common on the pickups in areas that use road salt ], it happens mostly at very low speed. The best way to find out the problem is to have the system scanned.

They have ABS and when you press the pedal hard the pedal vibrates. its the computer doing a pumping action for your. It grabs and releases the breaks so they dont lock up and it allowys you to stear your vehicles while the brakes are firmly pressed.

check for warped rotors

most likely you have a problem with your calipers and how they are gripping with abs assist control on rotor.

There's speed sensors at each wheel. You may have got some contamination in front of one of them... sounds like the abs is trying to compensate for un equal speed at each wheel... and something may be blocking a proper read at one of the wheels...

This is usually caused by one of the front wheel speed sensors dropping signal under 10MPH. the first thing to try is to remove both front wheel speed sensors (Behind brake rotors) and clean the area where te sensor goes into the hole. Then lightly grease the sensor O ring and reinstall it.

go to ford dealership and have them scan your truck with a scan tool