ABS activating at slow speed

[CapnDean]

This is a new thread on an issue that I posted in an earlier thread. My nephew bought a new truck same as the one I just bought. Well his is a Chevrolet mine is GMC but otherwise. Similar Mileage equipment etc.
06 Chevy 2500HD LT CC 4wd.

We are chasing down the last minor issue. The brakes work fine for the most part. When stopping, as you get to the bitter end of the stop, it feels like the brakes begin to go into antilock and give a slight rumble. It is as if one wheel is going into pulse mode. Also, after stopping straight, as the rumble begins the pedal feels spongy and the truck will pull slightly left.

Flushed brake fluid and replaced master cylinder, bled bled bled...no change.
Pads are fine, rotors are fine. Pull the ABS fuse and the problem goes away. But lights off the abs and brake lights on the dash.

Replace the fuse, the problem returns. Disconnecting a wheel sensor throws the abs light only....but the problem ceases as well. Truck stops great no pulsing no pulling.

We have whittled it down to either the ABS pump or one of the wheel sensors.
Going to try to find a code reader that will read the ABS system to see if that has thrown a code that we dont see on our stock OBDII scanner.

Anybody seen this got insight?

[happyduramax]

here in the rust belt we see it all the time rust builds up under the abs sensor on the hub and opens up the air gap on the sensor. first check your front hubs/wheel bearings to make sure there tight no movement .if they are good remove the abs sensor and clean under the sensor apply some grease to sensor and reinstall torq sensor mounting bolt to 13ftlbs if you have a scanner you can watch and see what sensor is causing the activation hopes this helps

[battlegraduate09]

wheel bearing

[CapnDean]

AWESOME! Thanks!

[battlegraduate09]

The Timken brand is the favorite to use.

[bubblebutt]

sensor dropping out- most sensitive at slow speed check for rust build up under sensor mount, also seen this when one tire is smaller size

[GMCustomerService]

@CapnDean, I hope the suggestions that you’ve been provided help you with this. I look forward to reading what the problem was and how you fixed it.

Michelle, GM Customer Service

[greendog]

I would check the wheel speed sensors. One of my rears went and it started doing the same thing yours is. After a while I started to get messages on my dic too.

Sent from my SGH-I747M using AutoGuide App

[CapnDean]

Read with ABS code reader....only codes were ones that we caused from removing the fuse and disconnecting the wheel sensors on the front right and left.

Repalaced abs pump: No change Ordered front abs wheel speed sensors. Will see tomorrow.

Inspection of bearings and front sensors, clean no rust bearings have no slop.

Still digging. I am betting that it is the right front wheel speed sensor because when it lights off the truck pulls left ever so slightly.

[battlegraduate09]

jack the tuck up and wiggle the tire 3-9 oclock. if you have play, its a wheel bearing