OT-silverado brake issue question

[Ray]

I have an 01 silverado 1 ton duramax pickup.When the brakes are applied within a few seconds the pedal will vibrate slightly then will make a noise like the antilock brakes.The truck has 60000 miles,sets mostly with a 30ft trailer hooked up.
It never had real good brakes,even when new.I just had new brakes and rotors installed and it still does the same thing.At first it only did it pulling the trailer,now it does it with the empty truck.My dealer says that's normal.With 4 wheel disc brakes i think it should have better braking.I got rid of a dodge cummins 1 ton because it did the same thing,only it's brake pedal would go to the floor and you would have no brakes.they couldn't fix it either.
 

[Michael Soldan]

You said it acts like the ABS,slight pulsing of the pedal when you apply? I wonder if your wheel sensors are dirty or faulty.Check your hubs and make sure no wires are cut or rubbed through.Sometimes cleaning the sensor/hub with a wire brush,making sure there is no grease and /or mud which could affect the sensor. It sounds strange to me,could there be air in one of the brake lines. Those trucks need a powerball to properly bleed them,we ran into one at the shop I worked at,we had put new rotors,calipers,pads,hoses and couldn't get a good firm brake,bled lines and worked on that truck for hours(It was a Chevy),were not happy with the brakes,after replacing everything,they still seemed soft to me,but the customer thought they felt good..go figure..
 

[Jim in MN]

Silverados of that generation had a lot of problems with the ABS pumps (inside the frame rail under the driver seat). There is an electronic box on top that goes bad. Big money to replace from GM but there are companies rebuilding them too. I have read that you need a computer to run the pump and bleed the brakes. My 99 with 300k miles is unplugged and will stay that way. I can live without ABS.
 

[cshess]

My 2002 Dodge had fine brakes till had to make emergency stop!! Turns out i diid not see ABS light was on cause it was hidden.on lower left side. Real problem was corosion had shorted trailer plug in had gotten into trailer plug an had blown abs fuse in box under hood.
 

[retired farmer]

Boss has a 93 Dodge with cummins. Brakes started going to the floor a year or so ago. They ended up putting about three supposedly new brake boosters on it before they got one that seems to work.
 

[Hoenes]

I had a 95 1500 WT that did the same thing. (Vibrated and made a strange sound) Turns out it is the transition from anti-lock, to no anti-lock. I hate to admit it, but I keep driving it, and the vibrating and the noise went away. The ABS light will stay on though.
 

[bgud]

Hi Ray couple of questions for you first did you put pads and rotors on both axles and second does this happen when you first apply the brakes or when your almost stopped
 

[RickieBlue]

GM had issues around that time period where rust would build up on the hub and push the ABS pickup away from the tone wheel. It usually shows up at a slight brake application and at a slower speed like under 10 mph. As you come to a gentle stop it will activate before you come to a stop and sometimes it is tough to get the truck stopped. If this is what it is doing, you need to remove the front ABS sensors and clean up the area where it mounts to the hub so the sensor is back to the normal spacing from the tone wheel. There is a factory bulletin on it and your dealer should be well aware of it. Let us know how you make out! Before I retired, where I worked, we had over 100 GM pickups and we had issues with about 8 to 10% of them.
 

[MisterT]

[Ray]

The original front pads looked like new,so they used them over.Front and rear rotors were replaced.It did this before the brake job.It only does it at slow speed,like pulling up to a light or just about stopped.
 

[bgud]

The problem is rust build up under the front abs sensors. You will need to remove the sensors and clean the rust off the hubs. Make sure you put some grease on the sensors and hub mounting surface to prevent it from happening again.
 

[Kyle in KY]

Jim in MN is right on. You have a distribution block on the drivers inside frame rail that works in conjunction with the master cylinder and the ABS system. GM has had problems with the distribution block for years. If you climb under the truck, there will be an electrical connector going to the distro-block. Disconnecting the sensor will stop the pulsing and back feed into the pedal. Disconnecting it won't affect the brakes, it only eliminates the ABS input, meaning you won't have anti-lock brakes. You can replace the block for around 1700, but be careful if you have rust build up on the lines going into the block. The lines tend to twist and break if very rusted. Don't waste your money on the remanufactured distribution blocks because you'll be doing the job over again in a few months.
I have had good luck with ones from the junk yard if you can find them. They can be hard to find sometimes. Junk yard part is about half price, still kind of spendy. Good Luck
 

[MarkB_MI]

I don't know about the one-tons, but the rear disk brake rotors on our half-ton had a lot of problems with rust. It was my wife's vehicle, and she seldom made stops hard enough to activate the rear brake. I'd sure start with resurfacing or replacing the rotors.
 

[D beatty]

Had a 97 GMC k-1500 4x4 that something simular. They replaced pads and rotors but still did the same thing. They ended up putting new wheel bears assembly in and that stoped the problem.
 

[scotc]

By-pass the ABS pump. When it goes bad it will let the pressure off the rear brakes and your pedal floors itself.