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Super Mechanic
Super Mechanic, Master technician
Category: Chevy
Satisfied Customers: 17220
Experience:  29 yrs. exp., ASE master, cert. in G.M. electrical, a/c, susspension, brakes, electronic steering
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2004 chevy suburban: occasional ABS service light come on..resets

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2004 chevy suburban has occasional ABS service light come on. Usually resets with key cycle. what could be the cause?

Hello and welcome to Just, Super mechanic here. About your vehicle.



There are several areas of the ABS system that will cause the light to come on.


Do you know what trouble code(s) are stored?


You will want to have the code(s) read to know what area may have caused this.





Customer: replied 7 years ago.
There are no stored codes. I have not been able to duplicate the issue with the reader connected
Does the ABS activate when the light comes on, or is it just the light staying on?
Customer: replied 7 years ago.
When the light is off and you come to a stop, as the vehicle nears zero mph you feel a chattering in the pedal. When the light is on there is no chattering when the vehicle nears zero mph.

There has been a service bulletin for that type of concern. Here is what it states.




Brakes - Low Speed ABS Activation/No DTC's Set


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

Date: May 01, 2009

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

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).



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.


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.


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.
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Customer: replied 7 years ago.
Hey Super Mechanic, The bulletin makes sense for the chattering pedal. I will dive into it this weekend. Is this the root cause for the occaisonal MIL? The light usually comes on when the vehicle is moving at parking lot speeds.
That is probably what it is, but check it to be sure, thanks