Help with intermittent ABS issue

Adamant41

Member
Hey guys so I noticed I can drive my truck for days with out this happening it just randomly starts I will be driving then the abs and brake light come on and after so long it will shut itself off I’m lost on what it would be the fluid and everything is good
 

aaserv

Well-Known Member
Could be a few different things causing it but more than likely its an ABS problem and the brake light just comes on anytime the ABS does on your model. There is only a couple things could make the brake light come on by itself. Good chance it will have to do with a speed sensor and more likely the wiring connector than the sensor itself.
Regardless when the ABS light comes on it should store a code that can be read by an OBD2 reader. Ck the codes and go from there....
 

gmcman

Well-Known Member
Worth asking....but do you by chance have a mismatched tire size? Bald tire on one front wheel and a new tire on the opposite side?
May not throw a code on our platform but will on some others.
 
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Adamant41

Member
I have the trailblazer ss rims on it with 285/60/20 or something like that but it was doing it when I had the stock tires on as well
 
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Adamant41

Member
Could be a few different things causing it but more than likely its an ABS problem and the brake light just comes on anytime the ABS does on your model. There is only a couple things could make the brake light come on by itself. Good chance it will have to do with a speed sensor and more likely the wiring connector than the sensor itself.
Regardless when the ABS light comes on it should store a code that can be read by an OBD2 reader. Ck the codes and go from there....
Am I able to go to Autozone or that kinda place to get that checked out? Or is that a shop computer?
 

Mooseman

Moderator
Moved to proper section and changed title for more responses.

It depends on what scanner that particular parts store uses. Most can only read P powertrain codes.

You could get yourself an ELM 327 OBD adapter and the Car Gauge Pro app on an Android device. It's one of the very few apps that can read ABS codes. And a lot of times, some of these codes can only be read while the light is on as it might not be able to pull historical codes.
 

Chickenhawk

Well-Known Member
Most Innova scan tools now have ABS codes. I also use the BlueDriver and like it.

We cannot emphasize enough how important it is to get those trouble codes. Wheel speed sensors are a common problem, but the important thing to remember is that the code is NOT the cause; it shows the symptoms. For example, most wheel speed sensor problems can be fixed by replacing the hub. If the code shows loss of communication to the EBCM, then replacing the brake control module would be a HUGE waste of money. This problem can be fixed in five minutes with a wrench, wire brush and some undercoat paint.
 

Maverick6587

Silver Supporter
I agree with @aaserv it's probably one or multiple wheel speed sensors. They tend to get corroded and cause intermittent ABS issues. More than likely it's one of the front two speed sensors.

Here's a video explaining what happens to the sensors and how to clean them to resolve the ABS issue.
 

JerryIrons

Well-Known Member
Could be wheel speed sensor, maybe electrical connector even. But like others said, get a scanner that can read ABS codes, they are different and not all scanners read them. Even if the lights go out ABS codes are stored.

Lots of times when a speed sensor starts to go bad the vehicle will engage the ABS at slow speeds on dry pavement, a classic one is right before you stop at a stop sign, the abs engages briefly. It's super annoying!
 

MRRSM

Lifetime VIP Supporter
While the OBD2 Scanner(s) can make an Errant ABS Code Diagnosis, there is a much more Direct Method of approaching this problem by following along with what this VOP (Video Original Poster) does when using his Digital Multi-Meter to probe the ABS Sensor's 2 Pin Harness Connector.

The ABS Sensor functions by its 'near proximity' to the Rotating Internal Notched Reluctor Wheel inside of the Wheel Bearing Housing. With the Tip of the Plastic Covered Micro-Coil Transducer sticking down inside from the Base of the ABS Sensor, it is supposed to pick up Fluctuations of Alternating Current that, if nominal... should read about 450 Milli-Volts on the DMM Screen when spinning the Wheel By Hand at Very Low RPM.

Anything less for the Milli-Volts Reading can indicate either a Bad ABS Sensor (not very likely) or the sad, but easily rectified condition of having a Thick Layer of Rust Scale Build Up swelling the Outer Cast Iron Axle Bearing Housing. This Junk can thicken bad enough to elevate the Base of the Plastic ABS Sensor Body and make it 'tall' enough to move that cylindrical coil well up and away from those Tiny Reluctor Wheel Teeth. The ABS Malfunction follows on whenever this occurs.

This Dude Really Knows His Stuff and takes the Viewer through every step of How to do this Diagnosis with your DMM or DVOM and perform this Repair:

 
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Maverick6587

Silver Supporter
I have a random ABS issue where the stabilitrak light comes on randomly. I lost my one scanner that reads ABS so, I decided to just pack the Tech 2 in the vehicle until it comes on again. Finally got it yesterday, it's the Steering Wheel Position sensor going bad. Needed a scanner for that though.
 

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