2000 Sierra abs

[gromage1]

I noticed recently my 2500 Sierra 4x4 abs pulsates slightly when I come to a stop, not all the time but at very slow speeds just before the truck comes to a stop, I just had brakes put on it and the rotors don't look to bad, any suggestions as to what to check next? I read that the hub bearings are a common problem on these trucks are they a big job to change?

[frdfandc]

Its probably not your ABS. The ABS will not activate if your below 10 or 15 mph. You probably need your rotors resurfaced since you just installed new pads.

[nonstop]

Mine does this too. At a crawl it'll pulse, and give me that no stopping feeling.

 

Not sure what it is.

[frdfandc]

If the feeling is at a crawl, its more than likely brake pad shift. My 03 does the same thing like when I'm creeping up on a light. I really wouldn't worry about it.

 

 

BTW - is the ABS light on? If the light is not on, then you don't have anything wrong with your ABS.

[chev_tech]

It is caused by excessive clearance between the front speed sensor mounting surfaces and the reluctor ring. Cause usually by rust or corrosion buildup between the two. This condition will NOT set an ABS code, as the EBCM is only doing what it sees in the speed sensor readings. There is even a bulletin for this concern now.

[willfxp]

I have a small question to tack on regarding a similar issue...

 

On my '01 1500, when I'm braking on loose gravel, it would feel the brakes vibrate/pulsate rapidly. It doesn't feel as 'strong' as when I slammed on my brakes before (and was pretty sure that was ABS). Is this ABS too? I should have asked this question before while it was still fresh in my memory.

 

Thanks!

[gromage1]

Thanks for all the replies, the abs light isn't on. I'll have to take a look at the sensor clearance thing. What's the remedy, just cleaning them up? I looked into rotors for this thing, man they ain't cheap. I'm sure its the abs, I pulled the fuse and it doesn't do it. Thanks again

[stan_kolo]

My 99 Silverado ABS brakes would kick in when I was coming to slow stop. The problem was the front ABS sensor. This sensor is part of the front wheel bearing. They cost about $150. Once both wheel bearings were replaced the problem went away.

[frdfandc]

I have a small question to tack on regarding a similar issue...

 

On my '01 1500, when I'm braking on loose gravel, it would feel the brakes vibrate/pulsate rapidly. It doesn't feel as 'strong' as when I slammed on my brakes before (and was pretty sure that was ABS). Is this ABS too? I should have asked this question before while it was still fresh in my memory.

 

Thanks!

Anytime the ABS sensors see any type of wheel lock up, the ABS will engage. This will happen on any type of surface if you loose traction (gravel, snow) and the brakes start to lock up. My 03 does this going over rutted roads with the brakes applied.

[asepgrad98]

there is a bulletin for teh old style trucks, the newer ones could do it also i assume.

 

Antilock Brake (ABS) Activation At Low Speeds (Clean Wheel Speed Sensor Mounting Surface) #02-05-25-006A - (11/26/2002)

Antilock Brake (ABS) Activation At Low Speeds (Clean Wheel Speed Sensor Mounting Surface)

1999-2000 Cadillac Escalade

 

1995-1999 Chevrolet Silverado (Old Style)

 

1995-2000 Chevrolet Suburban, Tahoe (Old Style)

 

1995-2003 Chevrolet Astro Van, Blazer, S10

 

1995-1999 GMC Sierra (Old Style)

 

1995-2000 GMC Yukon, Yukon XL (Old Style)

 

1995-2001 GMC Envoy, Jimmy

 

1995-2003 GMC Safari Van, Sonoma

 

1995-2001 Oldsmobile Bravada

 

This bulletin is being revised to change model information. Please discard Corporate Bulletin Number 02-05-25-006 (Section 05 -- Brakes).

 

Condition

Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph). Upon investigation, the technician will find no DTCs set.

 

Cause

The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface.

 

Correction

Measure AC voltage and clean wheel speed sensor mounting surfaces.

 

Raise the vehicle on a hoist.

Disconnect both the front wheel speed sensor harness connectors.

Place a DVM across the terminals of each sensor connector.

Rotate the wheel with hand speed and measure the ACmV's. The reading should be at least 350 ACmV's.

If the reading is between 200 and 350 ACmV's, remove the wheel, caliper and rotor in order to gain access to the speed sensor.

Remove the wheel speed sensor and plug the hole to prevent debris from falling into the hub during service.

Clean the speed sensor mounting surface on the hub to remove rust and corrosion.

 

Important

Make sure that the sensor sits flat on the hub. If the sensor flange is distorted, replace the sensor.

 

 

Apply a thin layer of bearing grease to the hub surface prior to sensor installation.

Install either the original sensor or a new one in the hub and secure the sensor. Ensure that the sensor is seated flush against the hub.

Install the rotor, the caliper and the wheel.

Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel by hand. The voltage should now read at least 350 ACmV's.

[gromage1]

Thansk for all the info folks, I pulled the sensors and cleaned everything up. Works great, who da thunk.