ABS engaging when it should not be, ideas?

rodehawg

Original poster
Member
Jul 19, 2012
13
Hello everyone. Sorry if this is not the proper forum to post this in, but it is the closest fit I could find. This is in regards to my dad's 2003 Chevy Astro van. I'm not sure what motor he has but I do know he has all wheel drive.

Anyway, the issue is that whenever he is braking while slowed to almost a stop, his ABS seems to kick in. This does not happen when he applies the brakes at speed. It's only when near coming to a stop.

Update: just got off the phone with him. He said it happened yesterday but now today the issue has dissappeared. Prior to yesterday, he has driven that van very little over the past few months. Perhaps the issue has self resolved, but then again maybe not. I thought I would just see if anyone has any big ideas pop out at them.
 

Robbabob

Member
Dec 10, 2012
1,096
Simple fix if you can remove the wheel and get access to the ABS sensor.

copy and paste this into Google search (use the quote marks) "cleaning abs sensor site:gmtnation.com"

choose which thread you want to follow. Some are very detailed.

For our fix,
1. remove sensor,
2. roll a litte paper towel and stuff into the sensor hole
3. used a flathead screwdriver to scrape debris
4. wipe sensor end
5. removed paper towel wad
6. put sensor back.

There is one screw holding it on, I hear if you break the pin on the other side, not to worry... the one screw will be fine.

Good luck!
 

mrphoenix80

Member
Jan 1, 2013
251
My fix is the same except I wire brush the rust off and then paint the surface. Then after I remove the towel I add a dab of grease in the hole.
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,028
Brighton, CO
Not sure if that works or not... I just went ahead and had the wheel bearings replaced on my GMT when I had this same exact problem!
 

Metsämies

Member
Mar 28, 2012
15
Check the fastener that holds the sensor in place, if its loose it will act just as you explained. You can also test the sensor with a DMM to see if it is functional.
 

Mark20

Member
Dec 6, 2011
1,630
Metsämies said:
Check the fastener that holds the sensor in place, if its loose it will act just as you explained. You can also test the sensor with a DMM to see if it is functional.

How do you do that?
 

6716

Member
Jul 24, 2012
821
rodehawg said:
Thanks for the info guys. We'll have to look into that.

Did that do the trick?

This started happening for me after I did some work where I took the hub off, and instead of unclipping the ABS sensor wire at the connector, I took the sensor out of the hub. The sensor must have picked up some grit or something in the process.
 

Metsämies

Member
Mar 28, 2012
15
Mark20 said:
How do you do that?

Get get the tire off the ground, then probe into the wheel speed sensor (ABS Sensor) leads. You can use a couple of T-pins, push them in at the spot were the wire enters the connector DO NOT push them through the wire insulation. Set the multimeter to measure AC voltage . Turn the wheel by hand at about one revolution per second. If the sensor is good, there will be an AC voltage of between 50 and 700 millivolts.
 

Mark20

Member
Dec 6, 2011
1,630
That's easy. I've got an old oscilloscope that will also work well for that.
 

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