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Discussion Starter · #1 · (Edited)
I recently had a few messages on the dash come up that have left me scratching my head. Two messages show when I start up, "Stabilitrac," and "Trailer Braking System." I also notice that the Off Road Screen with vehicle angles, etc does not show any data. I got it scanned for codes at the local parts place but they came up with nothing and do not have ABS Code capability.

Thought it might be an ABS sensor but have no way to localize which one. I'd prefer to handle it myself rather than pay some shop big $$$ for something simple.

Any thoughts?

Truck just turned 60K.
 

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Discussion Starter · #2 ·
As a follow up. Got my hands on a code reader that reads ABS codes and narrowed the problem down to the right front ABS Speed Sensor. OEM part enroute.

Surprisingly, the cheapest options were the local dealer or amazon for OEM at about the same price!
 

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Discussion Starter · #5 ·
ABS Sensor fixed the problem. I was able to get the code figured out with an OLD code reader and some creative vehicle selection on the reader.
 

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ABS Sensor fixed the problem. I was able to get the code figured out with an OLD code reader and some creative vehicle selection on the reader.
I have exactly the same issue on my 2017. I scanned it last night with a friends SnapOn scanner. Mine is the drivers front. I start out like this. I start truck with ABS, TC and Stabilitrak warning lights showing and I have to dismiss the Stabilitrack message on the dash. I start driving, I can feel the ABS puslating with light brake application but after I roll a little ways the lights go out. I'm like "great"! Then as I drive a little bit, maybe 100 yards, I get a Stabilitrak warning, then a trailer braking system and I light up the ABS, TC and Stabilitrak warning lights and I have no ABS but the brakes work just fine.

When we scanned it while driving we can see the other 3 wheel speeds being the same but the front left sensor keeps reading erratically. One second it's matching the others, then the next it's reading like 2 MPH while the others are at 25 for example, then it'll match the others, then read 15 MPH. I was thinking either it's a chafed wire as we are known for having a chafing wire issue or it's the actual speed sensor.

[Edited:] Looked it up on YouTube and the swap appears to be pretty simple. I can get it locally at NAPA for like $27 or $14 thru RockAuto for ACDelco. personally I'd rather have ACDelco but I won't be able to get it before leaving. Cheap enough to just swap out.
 
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I have exactly the same issue on my 2017. I scanned it last night with a friends SnapOn scanner. Mine is the drivers front. I start out like this. I start truck with ABS, TC and Stabilitrak warning lights showing and I have to dismiss the Stabilitrack message on the dash. I start driving, I can feel the ABS puslating with light brake application but after I roll a little ways the lights go out. I'm like "great"! Then as I drive a little bit, maybe 100 yards, I get a Stabilitrak warning, then a trailer braking system and I light up the ABS, TC and Stabilitrak warning lights and I have no ABS but the brakes work just fine.

When we scanned it while driving we can see the other 3 wheel speeds being the same but the front left sensor keeps reading erratically. One second it's matching the others, then the next it's reading like 2 MPH while the others are at 25 for example, then it'll match the others, then read 15 MPH. I was thinking either it's a chafed wire as we are known for having a chafing wire issue or it's the actual speed sensor.

[Edited:] Looked it up on YouTube and the swap appears to be pretty simple. I can get it locally at NAPA for like $27 or $14 thru RockAuto for ACDelco. personally I'd rather have ACDelco but I won't be able to get it before leaving. Cheap enough to just swap out.
my zr2 has the exact same issue. Did you get it fixed and what parts did you replace?
 

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my zr2 has the exact same issue. Did you get it fixed and what parts did you replace?
Sorry, didn’t post an update. I change the left wheel speed sensor for $25 but it didn’t fix it. I think I’m either suffering from the dreaded chafed wire problem or maybe the hub ring is having trouble. When I changed the sensor, the old one had what looked like sand and grime on it so I’m wondering if a wheel seal is bad and crud got in there and maybe messed something up. I’ll try the wiring first cause that’s cheaper than diving into the hub. Attaching a photo of the old sensor if anyone has an opinion.
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Tough call on the sensor. The first think I did when the issue first happened was clean each sensor and blow out the hole they go in. There was a ton of brake dust I blew out but made no difference in the problem. I also had auto zone scan the light and they rod me the front passenger sensor was bad which I replaced and no improvement. I also wonder if the trailer brake module that sits on top of the spare tire has anything g to do with it. I also blew out and cleaned all the trailer connections snd the module connections. I just ordered a new at4 and need to fix before I trade or sell the truck.
 

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I'm pretty sure it's the left front sensor or it's wiring. Using a Snap-on I was able to read all 4 sensors while driving and it's definitely the left front that is the problem as the speed jumps all over the place while the other 3 are solid. Since I changed the sensor, my next suspicion is wiring so I'll need to check that next. The front left area behind the wheel and around the master cyl area are suspect areas with wire chafing. If that still doesn't fix it I'll need to then check the sensor is reading. I've never done it but I know there's a way to read the sensor directly from the connection. If that's wonky then it's the ring in the hub. I need to check this week if the trailer brakes actually work.
 

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I would tend to think it's more of a wiring issue if it's not the sensor. I would think the wiring would be more likely then the ring as there's nothing really that can go bad on the ring. I would check that spot under the (as they call it) AC muffler because that's in close proximity to the drivers side wheel and a known area of chaffing.

Makes me want to pull mine off now and have a look at it. Guess it's time to check all the harness before then can become a problem.
 

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I would tend to think it's more of a wiring issue if it's not the sensor. I would think the wiring would be more likely then the ring as there's nothing really that can go bad on the ring. I would check that spot under the (as they call it) AC muffler because that's in close proximity to the drivers side wheel and a known area of chaffing.

Makes me want to pull mine off now and have a look at it. Guess it's time to check all the harness before then can become a problem.
I agree as well. If GM put out a service bulletin on it and the sensor didn't fix it, probably that. I only mention the hub because on my 99 burb that was always the issue. Grime and moisture would get in there, rust builds up and then the sensor doesn't work. First time it happened I tried a sensor but didn't fix it. After that didn't work I would just change the hub. I was surprised when I pulled the sensor in the Colorado there was so much grime and what looked like sand in there. Because it's easy to get to, I may pull the passenger side sensor and have a look to see if they are the same grimy looking.

When you say the AC muffler, not sure what you're referring to? In another post it said to pull off the inner fender well to give easier access. I know there's like heat shielding pad under there if memory serves.
 

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I agree as well. If GM put out a service bulletin on it and the sensor didn't fix it, probably that. I only mention the hub because on my 99 burb that was always the issue. Grime and moisture would get in there, rust builds up and then the sensor doesn't work. First time it happened I tried a sensor but didn't fix it. After that didn't work I would just change the hub. I was surprised when I pulled the sensor in the Colorado there was so much grime and what looked like sand in there. Because it's easy to get to, I may pull the passenger side sensor and have a look to see if they are the same grimy looking.

When you say the AC muffler, not sure what you're referring to? In another post it said to pull off the inner fender well to give easier access. I know there's like heat shielding pad under there if memory serves.
It's an aluminum collector between the compressor and the outbound freon line. The harness goes under the bottom corner of it and it's a hard 90 deg angle so it can easily cut into the harness with the engine torquing during operation. When you pull the fender liner it will be right there in front of you.

On the sensor ring side of things I wonder if you could just hose the crap out of it with wd40 to remove the grime through the sensor hole while turning the tire by hand. I haven't had a need to pull mine so I'm grasping at straws...
 

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Well, checked the drivers side wiring. Pulled the inner fender well and found some chafing against the AC accumulator looking thing. Yellow wire and light purple, picture attached. Unfortunately didn't fix the StabiliTrac/ABS issue. Looked all over at ever other wire bundle I could find on the drivers side but nothing else close to rubbing anything. Guess next step is to check the passenger side. Anyone know a wiring diagram of where the driver sensor wire routes? Since I know the that wheel sensor is the problem, if I knew where it routed to I might be able to follow it along the bundle.
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Well, checked the drivers side wiring. Pulled the inner fender well and found some chafing against the AC accumulator looking thing. Yellow wire and light purple, picture attached. Unfortunately didn't fix the StabiliTrac/ABS issue. Looked all over at ever other wire bundle I could find on the drivers side but nothing else close to rubbing anything. Guess next step is to check the passenger side. Anyone know a wiring diagram of where the driver sensor wire routes? Since I know the that wheel sensor is the problem, if I knew where it routed to I might be able to follow it along the bundle. View attachment 9465
It's interesting because that harness for me goes under the bottom of that accumulator on my truck.
 

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I tried changing out the trailer module under the spare tire and the trailer brake unit in the cab this week with no success. I guess next week I will try changing out the wheel speed sensor using the extra one I have as I replaced the front passenger speed sensor already.
 

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I tried changing out the trailer module under the spare tire and the trailer brake unit in the cab this week with no success. I guess next week I will try changing out the wheel speed sensor using the extra one I have as I replaced the front passenger speed sensor already.
Wondering if you could get your hands on an OBDii reader and check the speed sensors while rolling down the road. This way you could see if one is actually reporting differently then the others.
 

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Wondering if you could get your hands on an OBDii reader and check the speed sensors while rolling down the road. This way you could see if one is actually reporting differently then the others.
Agree to the above! I know something is up with my drivers sensor reading. I can see it when rolling down the road but it's not the sensor because that fix is so simple to do that my truck won't make it easy on me so the search continues.....
 
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