abs goes on on dry pavement

[1970greenc10]

Hi, The abs brakes on my 03 silverado 1500 2wd go on even when I stop slowly on dry pavement. I saw on the 90's truck forum that rust can build up behind the sensor and cause a problem, does that happen on these trucks too. Also an unrelated problem, when I put my right turn signal on the flashers come on. I was thinking shorted out wire or bad connection in the column? Any help is always appreciated.
Thanks, Marty

[Special-Ed]

Happens on my suburban from time to time

Grease from sealed wheel bearing is splattering on the face of sensor and getting into the teeth inside the bearing... All I do is remove sensor. Clean face. Then look at teeth and with mini screw driver remove any grease between the teeth

That's for my front. No problems with rears.

I pull codes and or look at data on my scanner to determine the culprit.

I'm not saying this is your problem. It's just one of many solutions


Your signal flashers could be a bad bulb turn signal. Mine does that whenever a bulb goes bad. Your mileage may very

[1970greenc10]

Thanks, I'll give those a check.

[95 S_Trucker]

Rust will form on the bearing and push the sensor away from the reluctor ring. Remove the sensor from the bearing assembly. I get a small cloth rag and stick it in the hole. Then I use a mini grinder with a skotch brite and smooth it out. Then reinstall everything.

There is a TSB on this

The bulletin number is: 03-05-25-007D

You can try and google it

[95 S_Trucker]

Bulletin No.: 03-05-25-007D

Date: May 01, 2009

Subject: Antilock Brake (ABS) Activation At Low Speeds (Clean Wheel Speed Sensor Mounting Surface)
Models:
2002-2006 Cadillac Escalade, Escalade EXT
2003-2006 Cadillac Escalade ESV
1999-2006 Chevrolet Silverado
2001-2006 Chevrolet Suburban, Tahoe
2002-2006 Chevrolet Avalanche
2003-2006 Chevrolet Express
2007 Chevrolet Silverado Classic
1999-2006 GMC Sierra
2001-2006 GMC Yukon, Yukon Denali, Yukon XL, Yukon Denali XL
2003-2006 GMC Savana
2007 GMC Sierra Classic
2003-2006 HUMMER H2
Supercede:This bulletin is being revised to add the 2007 Silverado/Sierra Classic models. Please discard Corporate Bulletin Number 03-05-25-007C (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 the wheel speed sensor mounting surfaces.

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in the General Information sub-section of the Service Manual.
2. Disconnect both the front wheel speed sensor connectors at the frame and harness.
3. Place a Digital Volt Meter (DVM) across the terminals of each wheel speed sensor connector.
4. Rotate the wheel clockwise approximately one revolution per second. The minimum reading should be at least 350 ACmV's. If the reading is less than 350 ACmV's, remove the wheel speed sensor. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.
5. Plug the wheel speed sensor bore in order to prevent debris from falling into the hub during service.
6. Clean the wheel speed sensor mounting surface using a wire brush, sand paper, emery cloth, scotch brite, or other suitable material. Be sure to thoroughly clean the wheel speed sensor surface. There should be no rust or corrosion.
7. Check the sensor head to determine if it has been warped/distorted due to the corrosion build up or other causes. Check the mounting surface on the sensor head for flatness by placing it on the edge of a metal machinists scale or other suitable straight edge to measure the flatness. Check the sensor for flatness in multiple (minimum 3) positions/directions. If the sensor head is distorted, replace the sensor.
8. Apply (spray) two thin coats of the specified rust penetrating lubricant (corrosion inhibitor) to the complete sensor mounting surface on the bearing hub. Allow to dry for 3-5 minutes between coats. Use ONLY Rust Penetrating Lubricant, P/N 89022217 (in Canada, P/N 89022218).
9. When the corrosion inhibitor is dry to the touch (about 10 minutes), apply a thin layer of bearing grease to the hub surface and sensor O-ring prior to sensor installation. Use ONLY Wheel Bearing Lubricant, P/N 01051344 (in Canada, P/N 993037).
10. Install either the original sensor or a new one in the hub. Ensure that the sensor is seated flush against the hub. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.
11. Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel. The voltage should now read at least 350 ACmV's.

[1970greenc10]

Thanks, turns out the passenger wheel bearing hub assembly was bad, and the new one came with a sensor, so now I just have to clean the drivers side.
Thanks, Marty