Shop Discount Wheel Speed Sensors

2005 chevy silverado 1500 4.3liter engine 147,000 miles brake pedal vibrates and pedal goes lower right before astop and there is also a noise under the hood when this happens

How slow? Like parking lot maneuvers or below 5 mph?

ECHNICAL

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
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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).
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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.

my abs sensor light has been on , now the 4 wheel drive switch wont select 4 wheel ,only 2 wheel , this is ever since the abs light came on , I really don't care about the abs I drive and stop fine without it, its the 4 wheel selector I want to work again , can I pull a fuse or relay to get the 4 wheel selector to work normal again ?
ON A 2003 Nissan 4 WHEEL DRIVE PATHFINDER at/v6
Code Explanation
25

– Left Front Wheel Speed Sensor Open Circuit

Probable Cause

Open or short circuit condition
Poor electrical connection
Faulty Wheel Speed Sensor

I haven't done much with Nissan's ABS or the 4 wheel drive controls; but with you saying both issues started at the same time. I bet the 4X4 controller needs to see wheel speed from all sensors to operate.
You'll need to find where or who has gone open for the left front speed sensor circuit.

Dan. your Bet is a good one Dan I found it in the shop manual after you had mentioned it ,the ABS circuit is tied in with the 4 Wheel drive selection switch . See ABS at very bottom http://tinypic.com/r/11jw08p/5

Just keep picking away at it and you'll get it out.

Dan.

Nothing is going to get resolved until you have the ABS codes read to find out where the issue is. Post the code number here. 2003 Nissan 4 wheel Dr Pathfinder LE

Code Explanation
25

– Left Front Wheel Speed Sensor Open Circuit

Probable Cause

Open or short circuit condition
Poor electrical connection
Faulty Wheel Speed Sensor

Also.......... nobody here can tell you anything without the year, make, model and engine size.

Maserati or what is this? Perhaps Tonto knows,


T

Hi. The ECM shows the VSS. The speedo works. The next thought was the right front wheel speed sensor. Checked the wiring within the fender well & nothing appears abnormal. Cleaned & degreased the wheel speed sensor ring & the sensor optic. The light went out. Today was the third day driving it & now the light has come back on. I like to think I'm on the right track in replacing the wheel sensor. The brake light is also on. Thanks in advance for suggestions.

Have you scanned the ABS module yet? What did you find?

I have a 2003 Chevy Trail Blazer, I hooked up a cheap OBD to check and clear my service engine light when doing so I received a P code, no problem but then their were 4 C codes and I don't know what C codes are? Can someone please help with this matter. Thxs

Inspect your front hub bearings. Make sure they are not loose or grinding with the wheels jack up. Pull the wheel speed sensors and look inside and be sure where the sensor mounts isn't all pitted and rusted up causing the sensor distance from the tone ring to have changed. Inspect the wheel speed sensor harness for damage or chaffing.

so here is the problem, I have a 2005 scion TC, with 80,000 miles and at the end of the brake cycle weither coming from 60 mph or 25mph. the brakes skip and i can feel the pedal vibrate and the car slips forward and emmits something like an error sound. and then catches right after it only slips for a second. but is quite scary. i have had it in various shops since nothing comes up on the scanners they say that they cant find anything wrong.
any info on this issue would be greatly appreciated
thanks in advance.

From your description is appears the ABS system is activating right before you come to a stop. The ABS system uses speed sensors at the wheels to monitor the wheel speeds. The shop needs to monitor the wheel speed sensor inputs with a scan tool or oscilloscope to see if you have any erratic readings at slower speeds. Has there been any work done to the vehicle?

The wheel speed sensor's signal strength is affected by the gap between the sensor and the tone ring in the wheel bearing housing. If that distance is changed from rust jacking of the sensor, that will cause slow speed ABS activation.

Inspect all your wheel speed sensors for rust jacking.
Rust jacking means the sensor is being raised off the mounting hole by corrosion which changes the air gap.