2019 GMC Sierra AT4 (new body style) brakes screaming. Replaced brake pads. Challenging.

Dan VonDielingen · January 29, 2023

Posting this to try to help others. I have 2019 GMC Sierra AT4 New Body Style with 39000 miles and the breaks were screaming for these first several rotations (e.g. down the driveway) and after sitting for just a short period of time. The front was showing 67% left and the rears were showing 81% left. I don’t do any pulling with the truck. Called the dealer and they told me this was normal….told me something about semi metallic brakes and metal on metal squeal is normal until warmed up. I can tell you there is nothing normal about this. The brakes wake up my neighbors in the AM and my startle my co-workers when leaving work. I could find some info on the web…but not much. So, I decided to replace the front and rear pads on my own as brake squeal is not normal. I have normally replaced my brakes on older vehicles, so gave it a try. It was an adventure. I went to local advance auto parts store and bought the pads with the wear sensor. Part # was GNAD2173 and PXD2174H. Total for all pads/sensors for ~$130. The pads were ceramic and came with the replacement wear sensor. There is one sensor on the front left and rear left wheel. With parts in hand, I went for it.

Rear Brakes: I started with the rear. Removed the tire, and the job looked straight forward. Removed two 14mm bolts which allowed for the top of the caliper to come off. It was a bit difficult to get off as there was a plastic electronic emergency brake housing attached to the caliper but i was able to get it off. Replaced the pads and clips super easy. Went to compress the piston back to put the housing back on…and there was no compressing it. I went on line and found a very good short video on how to put a Silverado into emergency brake service mode. Title of video is “2019-2020 Silverado Turn On Brake Service Mode to retract emergency brake pistons / motors”. Basically, with truck off, press the brake pedal and then push in the emergency brake button for 10 seconds, take foot off of brake, finger off of of emergency brake button, and immediately press and release the emergency brake button. You will hear the emergency brake motor activating. You can then turn on the truck and will see a brake light with a wrench symbol flashing. This is how you know it is in brake service mode. I turned the truck off, then went to see if I could push back the piston. It pushed back with ease. I should have put the truck in the brake service mode first. The final step on the rear driver side wheel is to replace the wear sensor. The only tough part here was getting it disconnected at the harness. I ended up pushing the white tab away from the connector, and with a pair of needle nose pliers pulled the white tab out. Then there is a grey tab under the white tab that you can lift up/or push down (can’t remember) and the old wire disconnects with an easy pull. I then put the white tab back in, and inserted the new plug side of the sensor. It went in with ease and then I pushed down the white tab to secure the new sensor in place. I am sure there is an easier way but this is how I got it to work without breaking anything. The wear sensor easily slides into the brake pad in the groove. From there I put the caliper housing back on, secured the caliper with the two 14mm bolts, put the tire back on and went to the passenger rear. With the brake service mode still in place, I repeated all the steps on the passenger rear side (all steps but the wear sensor as there is not one on the passenger rear). With both rear brake pads replaced and wheels on, I went back into the truck and turned on the truck and with foot on the brake, and in park, I pushed the emergency brake button for 5 seconds, this takes it out of brake service mode (the light with the wrench goes out). Then, I took it for a drive, and the brakes worked fine. No error codes. The only thing I could not reset was the brake pad % on the driver information sensor. I have seen a couple posts on this, but seems like it has to be reset with a scanner if the wear sensor has worn yet (and my truck with 39K miles on it hadn’t yet “opened” the wear sensor. In summary, if did this again, I would put the truck in brake service mode as the very first step. All else was pretty straightforward. The sensor connection (at the harness) was a bit of a pain. I went slow as wasn’t too familiar with it, and didn’t want to break the plastic harness. By the way, the rear brakes still had 80+% of the pads left, so there was no reason they should have been squealing.

Front Brakes:

It was getting late, so I decided to do the front brakes the next day. The next am, I did the front brakes without putting the truck back in brake service mode. I thought the brake service mode was just for the rear brakes (that had the emergency brakes). This may have been a mistake (by not putting the truck in brake service mode). The other thing I didn’t do was disconnect the battery (which may have been a mistake as well). I say this, because when I replaced the front brake pads, it through a bunch of codes. ABS, traction control, other warning codes/lights and put the truck in a mode where couldn’t drive it beyond 43 mph and brake pad was very soft/slow/mushy. Will get to how i got that fixed here in a bit…but first, this is how I replaced the front pads. The front pads were easier than the rear to replace. Pull two cotter pins, pull the 2 pins, the brake pads easily come out. The pistons easily push back (but I think it was this that caused all the error codes). Guessing the new trucks have sensors that sensed the hydraulic fluid going backwards and didn’t like that. That is when I think if I did it again, I would probably put the truck in brake service mode and probably fully disconnect the battery. Not sure if this would prevent what happened to me…maybe someone else has that answer. Anyway, the front right was super easy to replace the pads and clip. The front left had the wear sensor. I disconnected it like on the rear. This one was a bit more challenging to get the wear sensor to clip on the brake pad. I just had to get under the truck a bit to better see the sensor / brake pad (truck was fully chocked for safety). Once i got to where I could see the connection, it went together easily. With both fronts done, and tires back on, I hopped into the truck thinking I was done. Turned the truck on, and got a ton of error codes (including the soft brake pedal and 43 mph limit). At that point I tried to put in brake service mode, thinking it might reset codes…but did not. I disconnected the battery, thinking that may reset codes, but it did not. I ended up calling a local brake shop, and had to have them clear the codes for me. They were able to do this in a few minutes, and then everything was back to normal (no 43 mph limit, brake pedal was normal, no warning lights, etc.). All of this, but my brakes no longer scream!!!

By the way, the fronts still had at least 70% of the pads left, so no reason for them to scream. All 4 rotors were also in great shape. As with the backs, I could not reset the front % brake pad sensor from the driver information center. Whenever I get this to the dealer for something, I will have them reset it (think that the brakes weren’t worn enough for the reset feature on the driver information center to be able to be reset). Saw a bulletin that it has to be reset with an onboard diagnostic scanner (which I don’t have).

All in all, this is way tougher than any other vehicle I have done due to the technology. The mechanical part is straightforward, it was the other electronic stuff that got me. Hope this helps someone.

calgator73 · January 29, 2023

40 minutes ago, Dan VonDielingen said:

Posting this to try to help others. I have 2019 GMC Sierra AT4 New Body Style with 39000 miles and the breaks were screaming for these first several rotations (e.g. down the driveway) and after sitting for just a short period of time. The front was showing 67% left and the rears were showing 81% left. I don’t do any pulling with the truck. Called the dealer and they told me this was normal….told me something about semi metallic brakes and metal on metal squeal is normal until warmed up. I can tell you there is nothing normal about this. The brakes wake up my neighbors in the AM and my startle my co-workers when leaving work. I could find some info on the web…but not much. So, I decided to replace the front and rear pads on my own as brake squeal is not normal. I have normally replaced my brakes on older vehicles, so gave it a try. It was an adventure. I went to local advance auto parts store and bought the pads with the wear sensor. Part # was GNAD2173 and PXD2174H. Total for all pads/sensors for ~$130. The pads were ceramic and came with the replacement wear sensor. There is one sensor on the front left and rear left wheel. With parts in hand, I went for it.

Rear Brakes: I started with the rear. Removed the tire, and the job looked straight forward. Removed two 14mm bolts which allowed for the top of the caliper to come off. It was a bit difficult to get off as there was a plastic electronic emergency brake housing attached to the caliper but i was able to get it off. Replaced the pads and clips super easy. Went to compress the piston back to put the housing back on…and there was no compressing it. I went on line and found a very good short video on how to put a Silverado into emergency brake service mode. Title of video is “2019-2020 Silverado Turn On Brake Service Mode to retract emergency brake pistons / motors”. Basically, with truck off, press the brake pedal and then push in the emergency brake button for 10 seconds, take foot off of brake, finger off of of emergency brake button, and immediately press and release the emergency brake button. You will hear the emergency brake motor activating. You can then turn on the truck and will see a brake light with a wrench symbol flashing. This is how you know it is in brake service mode. I turned the truck off, then went to see if I could push back the piston. It pushed back with ease. I should have put the truck in the brake service mode first. The final step on the rear driver side wheel is to replace the wear sensor. The only tough part here was getting it disconnected at the harness. I ended up pushing the white tab away from the connector, and with a pair of needle nose pliers pulled the white tab out. Then there is a grey tab under the white tab that you can lift up/or push down (can’t remember) and the old wire disconnects with an easy pull. I then put the white tab back in, and inserted the new plug side of the sensor. It went in with ease and then I pushed down the white tab to secure the new sensor in place. I am sure there is an easier way but this is how I got it to work without breaking anything. The wear sensor easily slides into the brake pad in the groove. From there I put the caliper housing back on, secured the caliper with the two 14mm bolts, put the tire back on and went to the passenger rear. With the brake service mode still in place, I repeated all the steps on the passenger rear side (all steps but the wear sensor as there is not one on the passenger rear). With both rear brake pads replaced and wheels on, I went back into the truck and turned on the truck and with foot on the brake, and in park, I pushed the emergency brake button for 5 seconds, this takes it out of brake service mode (the light with the wrench goes out). Then, I took it for a drive, and the brakes worked fine. No error codes. The only thing I could not reset was the brake pad % on the driver information sensor. I have seen a couple posts on this, but seems like it has to be reset with a scanner if the wear sensor has worn yet (and my truck with 39K miles on it hadn’t yet “opened” the wear sensor. In summary, if did this again, I would put the truck in brake service mode as the very first step. All else was pretty straightforward. The sensor connection (at the harness) was a bit of a pain. I went slow as wasn’t too familiar with it, and didn’t want to break the plastic harness. By the way, the rear brakes still had 80+% of the pads left, so there was no reason they should have been squealing.

Front Brakes:

It was getting late, so I decided to do the front brakes the next day. The next am, I did the front brakes without putting the truck back in brake service mode. I thought the brake service mode was just for the rear brakes (that had the emergency brakes). This may have been a mistake (by not putting the truck in brake service mode). The other thing I didn’t do was disconnect the battery (which may have been a mistake as well). I say this, because when I replaced the front brake pads, it through a bunch of codes. ABS, traction control, other warning codes/lights and put the truck in a mode where couldn’t drive it beyond 43 mph and brake pad was very soft/slow/mushy. Will get to how i got that fixed here in a bit…but first, this is how I replaced the front pads. The front pads were easier than the rear to replace. Pull two cotter pins, pull the 2 pins, the brake pads easily come out. The pistons easily push back (but I think it was this that caused all the error codes). Guessing the new trucks have sensors that sensed the hydraulic fluid going backwards and didn’t like that. That is when I think if I did it again, I would probably put the truck in brake service mode and probably fully disconnect the battery. Not sure if this would prevent what happened to me…maybe someone else has that answer. Anyway, the front right was super easy to replace the pads and clip. The front left had the wear sensor. I disconnected it like on the rear. This one was a bit more challenging to get the wear sensor to clip on the brake pad. I just had to get under the truck a bit to better see the sensor / brake pad (truck was fully chocked for safety). Once i got to where I could see the connection, it went together easily. With both fronts done, and tires back on, I hopped into the truck thinking I was done. Turned the truck on, and got a ton of error codes (including the soft brake pedal and 43 mph limit). At that point I tried to put in brake service mode, thinking it might reset codes…but did not. I disconnected the battery, thinking that may reset codes, but it did not. I ended up calling a local brake shop, and had to have them clear the codes for me. They were able to do this in a few minutes, and then everything was back to normal (no 43 mph limit, brake pedal was normal, no warning lights, etc.). All of this, but my brakes no longer scream!!!

By the way, the fronts still had at least 70% of the pads left, so no reason for them to scream. All 4 rotors were also in great shape. As with the backs, I could not reset the front % brake pad sensor from the driver information center. Whenever I get this to the dealer for something, I will have them reset it (think that the brakes weren’t worn enough for the reset feature on the driver information center to be able to be reset). Saw a bulletin that it has to be reset with an onboard diagnostic scanner (which I don’t have).

All in all, this is way tougher than any other vehicle I have done due to the technology. The mechanical part is straightforward, it was the other electronic stuff that got me. Hope this helps someone.

Good write up. You're right regarding disconnecting the battery after you put the truck in mx mode.

SteelD6 · September 3, 2023

Interesting read on replacing the rotors, pads, and sensors on the AT4. I also have a 2019 AT4 and not afraid to admit I am a bit daunted by my pending task of replace all of the aforementioned.

I have an onboard scanner...so will I be able to clear the error codes?

Dan VonDielingen · September 3, 2023

When I put in brake maintenance mode, I didn’t have any codes thrown on the back brakes. Also had to be in brake maintenance mode to push back the electric emergency brake. See that video referenced in write up for putting in the maintenance mode. For the front, I didn’t keep in maintenance mode, but if I did it again, I would. It was the front that threw a bunch of codes for me. I didn’t have a scanner with the ability to clear codes so had to take it to local shop. They just cleared the codes and was fine…and has been fine ever since. The most challenging part was getting it to the shop as it limited speed to 43 mph and the brake pedal felt very soft (slow to brake). Once codes were cleared, all went immediately back to normal. Previous comment also talks about disconnecting the battery as well when changing the brakes…I did not do this but doing that may prevent the codes as well.