Rear wheel speed sensor... - S-10 Forum
S-10 Forum is the resource on GM S-series trucks, Suspension, engine information, Body Modifications, painting tutorials.  Modifications to suit every need, budget and whim

Rear wheel speed sensor...

Go Back   S-10 Forum > Specific Model Forums > 2nd Gen Forums > Blazer / Bravada / Jimmy / Envoy
New User? Register Forgot Password


 
LinkBack Thread Tools
Old 04-26-2011, 05:51 PM   #1
Registered User
 
Join Date: Mar 2010
Posts: 7
Location:
User is: OffLine
Rear wheel speed sensor...

Can anyone tell me where the rear wheel speed sensor is,my brakes pulsate only when I have almost come to a complete stop,have almost hit the car in front of me several times especially when parking.The fronts tested OK I'm thinking its the rear or maybe the EBCM is bad I dont know can anyone help...No ABS light or codes present.2000 Blazer LT 4x4
Sponsored Links
Advertisement
 
Old 04-26-2011, 06:22 PM   #2
Electrical Mod
 
deathphoenix99's Avatar

 
Age: 24
Join Date: Oct 2007
Posts: 54,571
Location: Houston, TX
User is: OffLine
Re: Rear wheel speed sensor...

THe rear ABS sensor is the speed sensor in the transfer case. They don't have separate rear ABS sensors.
Old 04-27-2011, 12:59 PM   #3
Registered User
 
Join Date: Mar 2010
Posts: 7
Location:
User is: OffLine
Re: Rear wheel speed sensor...

Can you be a little more specific on the exact location,and what it looks like...Thanks...
Old 04-29-2011, 12:17 AM   #4
Registered User
 
Zeeke98's Avatar
 
Age: 40
Join Date: Aug 2003
Posts: 10,370
Location: Michigan
User is: OffLine
Re: Rear wheel speed sensor...

You SURE the fronts are good? There was a service bulletin for rusted sensors on the 4x4 hubs and low speed ABS activation.
Old 04-29-2011, 12:29 AM   #5
Electrical Mod
 
deathphoenix99's Avatar

 
Age: 24
Join Date: Oct 2007
Posts: 54,571
Location: Houston, TX
User is: OffLine
Re: Rear wheel speed sensor...

a lot of the Chevrolet trucks had a recall on the front speed sensors. 2wd as well. And I believe all they had to do was clean the contacts for the connector...but that's just what I was told.

The rear speed sensor is on the driver side of the transfercase at the tail shaft. Should be a 2 wire sensor and the only sensor on the transfer case in the back.
Old 04-29-2011, 12:34 AM   #6
Registered User
 
Zeeke98's Avatar
 
Age: 40
Join Date: Aug 2003
Posts: 10,370
Location: Michigan
User is: OffLine
Re: Rear wheel speed sensor...

I had the problem on my 4x4 Jimmy that was fixed when my dad bought it and had to put new hubs on it. I knew I had the GM bulletin around somewhere.

#02-05-25-006B: Antilock Brake (ABS) Activation at
Low Speeds (Clean Wheel Speed Sensor Mounting
Surface) - (Jan 5, 2006)

Subject:
Subject: Antilock Brake (ABS) Activation At Low Speeds (Clean

Wheel Speed Sensor Mounting Surface)
Models:
1999-2000 Cadillac Escalade
1995-1999 Chevrolet Silverado (Old Style)
1995-2000 Chevrolet Suburban, Tahoe (Old Style)
1995-2003 Chevrolet Astro Van, Blazer, S10
1995-1999 GMC Sierra (Old Style)
1995-2000 GMC Yukon, Yukon XL (Old Style)
1995-2001 GMC Envoy, Jimmy, Blazer, S10 Pickups
1995-2003 GMC Safari Van, Sonoma

1995-2001 Oldsmobile Bravada
Please discard Corporate Bulletin Number 02-05-25-006A (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 wheel speed sensor mounting surfaces.

1. Raise the vehicle on a hoist.

2. Disconnect both the front wheel speed sensor harness connectors.

3. Place a DVM across the terminals of each sensor connector.

4. Rotate the wheel with hand speed and measure the ACmV's. The reading should be at least 350 ACmV's.

5. If the reading is between 200 and 350 ACmV's, remove the wheel, caliper and rotor in order to gain access to the speed sensor.

6. Remove the wheel speed sensor and plug the hole to prevent debris from falling into the hub during service.


7.
Clean the wheel speed sensor mounting surface using a wire brush, sand paper, emery
cloth, ScotchBrite™, or other suitable material. Be sure to thoroughly clean the wheel speed sensor surface. There should be no rust or corrosion.

8.

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

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

9.

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 (Canadian P/N 89022218).
10.

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 (Canadian P/N 993037).

11. Install either the original sensor or a new one in the hub and secure the sensor. Ensure that the sensor is seated flush against the hub.

12. Install the rotor, the caliper and the wheel.

13. Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel by hand. The voltage should now read at least 350 ACmV's.
Old 04-29-2011, 09:38 AM   #7
Registered User
 
Join Date: Dec 2010
Posts: 350
Location:
User is: OffLine
Re: Rear wheel speed sensor...

I have found that once they start giving you problems you can clean them all you want but they will continue to give you problems.

You can buy a new sensor for the hub but again you will just have problems, it is almost like the sensor has to be a perfect distance from the reluctor wheel and it is set that way by the manufacture, when you take that sensor out it will never be right again.

It is best to buy new front wheel hubs, they come with a sensor already installed...I have been down this road many times and a few more things I have learned is buy only Timken Wheel hubs, Use a torque wrench and torque the axle nut to 103ft pounds, do not try to guess the torque or they will not last and you will have the same problem 6 months down the line. Do not under any circumstances use a impact wrench.

Golden rules

#1 Timken wheel hubs only...all others are junk!!!
#2 Torque axle nut to 103ft pounds!!!

Now you will probably never have to mess with them again...deviate from the golden rules and you will 100% for sure have issues again within a year or two! I have owned about 8 S10's in my life and went through about 20 wheel hubs because of abs problems and have tried everything from replacing just the sensor to discount/parts store brand hubs.

I have never ever had an issue with the rear abs sensor so to the original poster I would suggest you have your abs scanned and make sure what is bad before you do anything.
Old 04-29-2011, 04:15 PM   #8
Registered User
 
Join Date: Mar 2010
Posts: 7
Location:
User is: OffLine
Re: Rear wheel speed sensor...

I will give cleaning them a try,I put a scan tool on them and did not get any codes will keep you posted on what happens.. Thanks for the info.
Old 04-29-2011, 08:37 PM   #9
Registered User
 
Zeeke98's Avatar
 
Age: 40
Join Date: Aug 2003
Posts: 10,370
Location: Michigan
User is: OffLine
Re: Rear wheel speed sensor...

It's not just the sensor that needs cleaning. You need to get the rust and crud out of the sensor ring on the hub. I replaced the sensor on my 2wd with a sensor from the bad hub on my dad's Jimmy because I broke the wire on mine. It worked just fine.
Old 05-01-2011, 10:56 PM   #10
Registered User
 
Join Date: Mar 2010
Posts: 7
Location:
User is: OffLine
Re: Rear wheel speed sensor...

I took both wheel speed sensors out and cleaned them, one tests over 350mv the other is around 230mv can the one sensor maybe be bad should I try and replace it,before I go and spend the money on two new hubs...
Old 05-01-2011, 10:58 PM   #11
Registered User
 
Zeeke98's Avatar
 
Age: 40
Join Date: Aug 2003
Posts: 10,370
Location: Michigan
User is: OffLine
Re: Rear wheel speed sensor...

When I was looking for a sensor they were hard to find just the sensor and almost as much as a whole new hub was in some cases that comes with the sensor. I'm not sure what brand my dad ended up putting on his Jimmy as replacements. I put National brand by Federal Mogul on mine.
Sponsored Links
Advertisement
 

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the S-10 Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 04:02 AM.

Powered by vBulletin® Copyright ©2000 - 2011, Jelsoft Enterprises Ltd. SEO by vBSEO 3.2.0
SEO by vBSEO
vBulletin Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.