BrianBrianBrian

Final verdict: Brake drag culprit was caused by a leaking master cylinder that eventually compromised the brake booster. Fluid from the Master Cylinder was slowly leaking into the brake booster for quite some time. Tech said about a quart was drained from the booster. I asked how long this was going on and the answer was approx. 3 years~? Anywho, thank you to everyone that helped

I am experiencing this exact scenario. Do you happen to have any examples I can present to the dealership. They are replacing the Vacuum Pump for the second time (under the recall warranty, again) yet, this time my Booster has oil in it and they are charging me to replace the Brake booster and the Master Cylinder. It obvious this is a cause and effect thing. Brake Drag --- Booster and Master Cylinder have an internal failure.

You had said the answer right out the gate! Thanks man

Is the poppet valve part of the Brake Booster? As in, will it get replaced when they replace the BB.

Thank you for taking the time to aid in my troubles! I just got back from the dealership and I think you got your answer into the voting booth just in time to win the prize, lol. Sorry, fresh out of prizes after the cost of this roller coaster. Here is what they had to say: They are going to replace the MC and the Brake Booster. Also they are going to replace the Vacuum pump + Belt (for the 2nd time) and get it covered under the recall (again). Technician drove it and (thankfully)experienced the brake drag on the test drive. He opened the hood and disconnected the vacuum hose to the brake booster. While this obviously made braking a harder, the brake drag was gone and he was able to get the truck back to the dealership. I was told that they also found Hydro fluid in the booster. So that's all I've been given... They didn't really tell me what the exact failure point was other than its somewhere between the Vacuum pump and the MC. Thus, replace it all and it should be fixed. Should I be asking more questions to the dealership about this problem, or it is what is? I'll give another report back for the purpose of this thread after I get it home. Thank you to everyone here that helped. oh If anyone is curious, $1,333

I thought brake booster was only to assist in the pedal not restrict it from releasing? I did have the truck serviced for the Vacuum Pump thing back in 2019. They replaced both the pump and the belt. I am aware of a safety recall Part 573 Safety Recall Report There are several relatable issues that I'm having and what this recall addresses, however per the recall it only pertains to trucks with 3.08 ratio. Mine is not. But who knows at this point

Well... I'm officially tapping out! I've replaced the brake pedal sensor switch, Both left and right Wheel hub assembly, rotors, pads, calipers, and complete flush. Still have this damn issue. I just came across this post today and his scenario is damn near an exact as to what I'm experiencing. READ THIS POST I dropped off the truck yesterday, we'll see what the technicians find. &*()#*#*@)( !!!

Man... I am so happy to have found your post. I've been trying to solve this exact problem for the past month. This was my post <--- After replacing the Brake pedal sensor switch, Front: Wheel hub Assembly, Rotors, Brake Pads, Calipers, and I even replaced the trailer brake module for the cherry on top. And just like you, the damn brake drag is still there. I've been trying to explain this to everyone and it feels like I'm the only one with this problem until I read your post. I've only been able to drive locally before it gets so bad that it almost seizes. Like you, no codes have been thrown that I can relate to the issue. The next step for me was to replace the brake hoses and then the MC. But since you mentioned you performed these steps I'll skip it and put the $$ towards the GM technicians. I just dropped her off yesterday and the guy said he doesn't seem to think its a brake problem, but more likely an electrical problem. Said they'll need the truck for a few days to comb through the wires...(sounds cheap, gulp) This is old post but hopefully you can share your memory of the final fix?

Does this sound like bearings? VID20240111163916.mp4

VID20240111162224.mp4 VID20240111162303.mp4

Oddly enough, pulling over and pumping brakes and putting it reverse back into drive seems to temporarily get me back on the road. After speaking with a mechanic friend he sends to think it might be wheel bearing issues. I just put it up on Jack stands and when I try spinning the front wheels, I don't get a full rotation freely after letting go. I don't have a lift or after market wheels. I do have slight larger tires than factory (33x12.50 R20). I do tend drive in AWD from time to time. So maybe the bearings are shot? I would've thought bad bearings would've thrown a code or something. To answer your question, oddly enough, there is no pulling to either side. If not the bearings... My new conspiracy might be the torque converter. But again, that would most certainly throw a code or two given the outcome

Yes. I've tried turning off the grade braking, the stabilitrak, traction control, mashing the P-Brake. None of these options have worked unfortunately

I'm at the point to where I'm about to just replace the brake, calipers and rotors as a set. If that doesn't fix the problem then I'll start diagnosing brake booster and the master solenoid ect..

Interesting. I purchased the ac Delco ones from advanced Auto parts. Were the old pads you originally purchased sticking to the rotor?

I don't think it's a grounding issue but I don't know what it is yet, so can't eliminate that. If my issue was ground issue I'd likely be experiencing many other anomalies that are electric in nature to operation. I've seen a lot of folks deal with the grounding issue in here and fortunately I've yet to deal with that..fingers crossed. The braking system is engineered to be a mechanical feature of the vehicle in case the vehicle loses engine power, battery, or encounters a faulty ground so the vehicle can still come to a complete stop if one of those scenarios were to occur.

I think my next step will be to do a brake flush. I can't for the life of me see how the calipers would go bad this early...which leads me to think its fluid related because the issue happens after the truck has warmed up. I'll add your suggestions to the list of things to try, thanks.

I'm hoping someone can help me with this mystery. I cannot figure out what is causing my brakes to engage or rather not "disengage" after about 10-15 minutes of driving around. When the issue occurs, It starts off slowly with a slight sensation that the truck is suddenly pulling a heavy trailer, but then steadily becomes worse the further I go, eventually having to floor the gas to pull over safely off to the side. In the short term, If I pull over and pump the brake pedal a few times and start driving again it seems to fix the problem but only for a short while before it happens again. I have an OBD2 reader but it doesn't grant diagnostic data for brakes. I do have a live data read out of everything while the occurrence happens and would be glad to provide it if someone is able to use that info to narrow down a conclusion. When the issue happens, I can just let off the gas and the truck will come to a stop without needing to apply the brake. The feeling as if you're going through thick mud. I changed my brake pads about 3000 miles ago, so I don't see a correlation to my DIY brake job being the cause. The truck has 56K miles. Things that I've done so far: Replaced the Brake sensor control switch (code was thrown that mentioned Stabilitrak (it led me down a rabbit hole) (pain in the F'ng ass) - Still have issue. Took the calipers off and greased the pins. thought they might be getting stuck. - Issue is still present. Update: 01/20/2024 Replaced both front wheel hub assembly Added new brakes, Rotors, calipers Issue is still present. My next step would be to replace both the front calipers. <-- NOPE. I feel like I'm guessing at this point and the cause could be a Master Cylinder, Brake booster, Solenoid, bad brake fluid or lines. And to add, I have conspiracy monkeys in my head telling me it's all still related to the faulty GM vacuum pump issue. All this to say, if someone has dealt with a similar issue in the past and figured out the cause I would be grateful to hear from you. Past service history: Service Performed: 28K miles: Electronic Brake Control Module Reprogramming with SPS AIR CONDITIONING CONDENSER REPLACEMENT Vacuum Pump Replacement Power Steering Control Module Reprogramming with SPS Service Performed: 11K miles: SDM PROGRAM (@11,000 miles) Transfer Case Shift Control Module Reprogramming with SPS

I'm currently going through the same scenario. I can't say for certain if its the front brakes or what. But the feeling was as if the truck all of sudden was pulling a trailer uphill with four flat tires. I pulled over on the HW to check for flat tires, nope. No check engine lights either. Hopped back in, put her in drive and tried to get up to speed to merge and almost got nailed by an 18 wheeler ...I was punching the gas. Finally made it to the exit and into the gas station. Finally the DIC kept flashing Service Stabilitrak warning as I pulled in. When I let my foot off of the gas at the gas station the truck just stopped, no braking on my part needed. At this point, you could smell something wasn't right, but the only lights that were lit were Stabilitrak and the T/C traction control. I just decided to leave her there overnight, we had an appointment with Santa. Next morning, wife dropped me off. While I sat there waiting for the wrecker to tow I started it up the dash lights and messages were still present. I put it in drive, then into reverse, repeat a few times. The lights went away and no autonomous braking was felt. I did one quick low speed cruise through the gas station parking lot and everything seemed ok. Still had the wrecker take it home (4 miles). To note: at first I thought maybe this is what "limp home mode" was but wouldn't I have receive a warning indication from the truck that it was going into LHM? After the wrecker dropped her off, I tested it out in the neighborhood at low speeds and it seemed just fine. Later on I went to pick up my daughter from school and it started to happen again on the way home or 25 minutes from engine start; "Service Stabilitrak" warning flashed and it felt like the brakes were being smashed. I pulled over and repeated the process I did the day prior and was able to shake it again but only for a mile before it happened in my neighborhood...I just pushed fw and into the driveway. The computer threw one code (C0161) My research hasn't come across many others like this and the only suggested solution so far is to replace the Brake Pedal Position Sensor. The thing that makes it go away is to stop the vehicle and smash the brake 3 or 4 times and it seems to reset itself. I'm wondering if this has more to do with the vacuum pump than anything else. I did have the recall done for the low speed braking issue back in 2019 and all they did was do a reprogramming. Anywho, if someone has knowledge of this situation I'd love to hear from you before i try to invert my big ass under the floorboard to replace this position sensor.

I landed on this topic because I'm experiencing similar problems. When my truck gets up to speed around 40mph it begins to lose power and from what I'm learning everywhere this is what limp mode does. I never get a check engine light other than DIC message saying to service stabilitrak. This limp mode somehow feels like grade braking is being activated. The only code from the OBD is C0161 - ABS/TCS brake switch circuit malfunction. I've ordered the part and plan to replace the part, but for some reason my spidey sense are not optimistic that this is the cause of my limp mode.

Not sure if you've solved the problem here. But I'll add that this situation is happening with me right now. I did a fresh oil change and a full gas filler-up, decided to add a little fuel additive (Additech). That evening the family all loaded up to go out. The roads were very wet and there was a slight drizzle. About a mile onto the HW going 65MPH, my truck starts to feel like it is struggling to maintain speed. Felt like I had four flat tires pulling an RV uphill. I pulled over check tires, all were good. No dash lights were lit up. Hopped back in and started driving and almost wrecked trying to get up to speed to merge back on the HW. I took the next exit and barely made it to the gas station. When I pulled in, all I had to do was take my foot off the accelerator and the truck stopped immediately as if brakes were being applied already. Just prior to pulling in the station, my DIC was flashing the Stabilitrak dissabled message and the "T/C" light on the instrument panel was lit up. Left the truck there overnight and had it towed home the next day. Decided to start it up and put it into gear; Drive, Rev, Drive, Rev... The lights on the DIC dissapeared so I drove it around the hood for a slow mission and everything seemed normal. I'm at a loss for what happened other than to think that the fuel additive somehow confused the brain to think the truck was receiving more power than normal and communicated this to the EBCM which was probably compromised because of wet roads. Sounds like a wild assumption but the more I read up on the Stabilitrak and Traction control in relation to fuel delivery, it makes sense. Couple this with the code it registered

Yeah, 70 was the max. It was much better at 60. The difference, like you said, was huge. 1st time, I'm learning. Thanks

It makes total sense now. It was certain confusion on my part. Honestly, I never knew those things were called "Slide Ins" but rather "Truck campers". You're right, with all the verbiage and cross use of the words "camper", Camper Trailer, RV, Toy Hauler, ...ect it has been a little confusing.