2003 GMC Yukon ABS pulsing at low braking speeds

Tiny
BOATMANZZ
  • MEMBER
  • 2003 GMC YUKON
  • V8
  • 4WD
  • AUTOMATIC
  • 70,000 MILES
Recently I have experienced an issue with the front brakes. When braking and achieving a speed of about 5mph or less, the abs engages and pulses the brakes, causing the front end to shake bad and the pedal to drop. Brought to dealer today, told both front wheel hub assemblies needed to be replace for about a grand. Poked around the net, found maybe it is just a corrosion or debris issue with a speed sensor? I am in the 'salt-belt', upstate NY. Seems to be getting worse and worse.
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Wednesday, December 3rd, 2008 AT 5:48 PM

9 Replies

Tiny
BLUELIGHTNIN6
  • EXPERT
Hello
Thanks for the donation

A malfunctioning or dead speed sensor can cause a massive array of problems that are not necessarily inclusive or exclusive to themselves or a malfunctioning speed sensor/VSS respectively. The best way to tell if your speed sensor is malfunctioning is to see if any/all of the following problems occur ( these are for an automatic transmission):

Transmission is revving higher before it changes gears (most common symptom)

Transmission engages overdrive late, or in top gear, never (very common)

Brakes depressing erratically or harder than normal when coasting (somewhat common)

Speedometer is behaving erratically or does not move (more common in late model vehicles)

Check Engine Light is apparent, but sporadically.(More common in older vehicles)

O/D Off light is blinking, either at higher speeds or constantly (more common in foreign vehicles)

If you was told one or both of the wheel hub assemblies need replacing, you can check any play from top to bottom of each wheel (while jacked up and supported) and also listen for whirring noise from each side while driving. These are symptons of faulty/worn wheel hub assemblies.

Your vehicle should be equipped with an ABS Speed Sensor on both sides of vehicle. If you plan on replacing them, I suggest replacing one and if the problem persists, switch the new one to the other side of vehicle. If problem still persists, suspect dealer diagnosis was correct.

Hope this helped.
Thanks for using 2carpros. Com!
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Wednesday, December 3rd, 2008 AT 6:18 PM
Tiny
BOATMANZZ
  • MEMBER
Thanks for the quick response.

Yeah the first thing I did when I got hope was life the front end and check for any play in the bearings, none at all, rock solid.

To replace a speed sensor on a front wheel, does the hub need to be R & R'd? Or is the sensor externally mounted and somewhat easily changed out?
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Wednesday, December 3rd, 2008 AT 6:35 PM
Tiny
BLUELIGHTNIN6
  • EXPERT
To better assist you with this specific question, could you please let me know the exact model of the Yukon and the 8th digit of the VIN #? Thanks.
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Wednesday, December 3rd, 2008 AT 6:41 PM
Tiny
BOATMANZZ
  • MEMBER
2003 GMC Yukon SL 5.3L 4wd A/T 8th in vin is "T"
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Wednesday, December 3rd, 2008 AT 6:52 PM
Tiny
BLUELIGHTNIN6
  • EXPERT
Thanks for that.

Here are the removal instructions of FRONT speed sensor for the 4WD Yukon.

Raise and support the vehicle.
Remove the tire and wheel.
Remove the brake rotor (2).
Remove the wheel speed sensor (WSS) mounting bolt.


http://www.2carpros.com/forum/automotive_pictures/261618_Graphic_6.jpg



Remove the wheel speed sensor (5) from the hub/bearing assembly (4) by CAREFULLY pulling it straight out of the bore.


http://www.2carpros.com/forum/automotive_pictures/261618_Graphic_7.jpg



NOTE: DO NOT use a screwdriver, or other device to pry the sensor out of the bore. Prying will cause the sensor body to break off in the bore.

Remove the speed sensor cable mounting clip from the knuckle.
Remove the speed sensor cable mounting clip from the upper control arm.
Remove the speed sensor cable mounting clip from the frame attachment point.

Remove the speed sensor cable electrical connector.


http://www.2carpros.com/forum/automotive_pictures/261618_Graphic_8.jpg



Mounting bolt should be torqued to 13 lb ft (18 Nm) during installation.

Hope this helped.
Thanks for using 2carpros.com!
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Wednesday, December 3rd, 2008 AT 7:02 PM
Tiny
BOATMANZZ
  • MEMBER
Man I spent about 5 hours searching for this information today, wish I knew about you guys sooner! This is the EXACT info I needed, nothing more, nothing less, finally a place that is street level and can provide just what you are looking for. I bumped up the donation by 900%. Have a great Holiday season!
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Wednesday, December 3rd, 2008 AT 7:41 PM
Tiny
BLUELIGHTNIN6
  • EXPERT
Great, glad you got the info you needed. Thanks for using 2carpros. Com!
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Wednesday, December 3rd, 2008 AT 11:06 PM
Tiny
BOATMANZZ
  • MEMBER
Not sure how real mechanics deal with it when the existing speed sensor breaks off in the hub upon extraction - but I just dealt with it, check out the attached pic


http://www.2carpros.com/forum/automotive_pictures/280985_DSC05188_1.jpg

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Thursday, March 19th, 2009 AT 7:50 PM
Tiny
MARCOSLOPEZ
  • MEMBER
Is it possible to only replace the cable? My dog was after a squirrel and chewed the cable in half. Was wondering if I can replace the cable without taking apart the whole hub?
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Wednesday, January 19th, 2011 AT 5:12 PM

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