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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 found the brake pedal in my GMC Sierra 6.2 model 2014 is hard at idle after 2 to 3 presses. I cancelled the original vacuum pump line and connected the brake booster to the intake manifold vacuum source. The old line was covered with air filter element to avoid dirts to enter the vacuum pump. Now the problem is completely resolved. Is there any other options? Anyone tried this idea and appreciate if can share his experience and feedback. Regards,

https://www.whec.com/news/gm-under-investigation-for-faulty-brake-vacuum-pumps/5154566/?cat=565 "The U.S. government is investigating more than 100 complaints of poor brake performance on 2.7 million General Motors big pickups and SUVs." Hold your receipts if you have done any work, hopefully a recall comes out of this. I also think reporting your issues to the NHTSA may get this rolling out faster.

Hey guys, I got a 2015 Silverado 5.3l. 138,250km. started ticking sometime last winter. Would happen instantly at start up and last about 5 minutes then would fade away. Sounded like a lifter. Took it to the dealer they said they couldn't hear it. Sound went away so left it. Fast forward to this winter and as Soon as the weather started to cool down I noticed the ticking again. Took it back to the dealer said they couldn't hear it again. I went and picked up my truck right at closing, soon as I fired her up the sound was there but everyone was gone so no one to hear it. I took a video. Next day I called the dealer, sent the video. Took like a week to get back to me. In the meantime I had taken videos pretty much every time I started it. Long story short after a brief fight with them about them trying to say it's normal etc they agreed that it sounded like a noise coming from the valve train. Left my truck with them, they called me said they had to change all lifters. Went to pick up my truck and on start up the sound is still there. This was a month ago. Sent more videos and a previous video from before they did the work and they are saying they can't hear it again. Took it in in person they agreed that there's an issue again and they will look at it. Now they are saying it's possible bad injector noise but they can't figure out which one ?. In the meantime I took it to another dealership they changed the vacuum pump. After that the sound changed. Now it's no longer at start up but once the truck has reached operating temperature and is more of a dull sound. Took it back to that same dealer who did the vacuum pump and they said valve train noise and deffo not injectors. But they won't work on it because the other dealer already did. They didn't change the VLOM or the cam. I had/have no check engine lights. Truck runs awesome. Sometimes rough idle. Any ideas what it could be?

So I have had my truck into Dealer on multiple occasions for what sounded like a lifter tick. This ticking noise was loudest in the morning first thing when starting engine. With the hood open it sounds like a lifter sticking and coming from under valve cover. You also can hear it through the drivers side wheel opening. Since the dealer has recently replaced all lifters I decided to go ahead and replace the vacuum pump. I purchased one from Amazon for $128.83 and a Lisle Stretch belt tool 59370 for $15.00. ACDelco 12669488 GM Original Equipment Vacuum Pump and Lisle 59370 Stretch Belt Tool Upon start-up the loud ticking noise is gone. I can still hear the injector noise but it is not very loud compared to this noise I have been chasing for some time now. We will see how long this new designed pump lasts. It does not look as beefy as the original but if there is no noise I will be very happy.

I'm doing my best to isolate this ticking sound that is persistent, yet intermittent. Data so far: 2018 CC SLT 1500 6.2L 4WD Max Tow 19K miles, all stock Doesn't happen when motor is cold, much more prevalent when motor is warmed Doesn't happen when letting off throttle (only under application of throttle), can be heard in neutral, park, and in drive (not in reverse enough to tell--but it happens when transmission is not engaged) Sound follows steady or increasing RPM of motor Under light to medium load, noise is prevalent, under heavy acceleration it subsides (not because of engine noise) If I turn wheels hard left, the noise disappears, straighten wheels, it returns (like wheel is blocking noise from traveling) Sound only heard on driver side If I hit some oscillating bumps on the road, it can stop for a while before returning back (under varying loads as well) If left in tow/haul mode, at 2500 rpm under light load it can still be heard Ran 2 bottles of Red Line injector cleaner and it didn't eliminate/help noise The truck was silent until the 700 mile mark and I hit an expansion joint (nothing out of the ordinary) and the sound started and has remained ever since I've checked exhaust/manifold connectors and no sign of leaks (soot) I put a hollow aluminum rod (2 foot long) to the vacuum pump and did not hear any abnormal noises directly from the pump Obviously heard injector noises when put to the injectors; haven't had chance to stop on side of road when the sound disappears to run comparison tests Sometimes it'll run dead silent when driving down the road (after complete warm up) and power delivery doesn't change but noise comes back within a minute or two Sound heard in both V-8 and V-4 modes, and while in manual shift mode Use premium 91 gas ever since purchase (93 not available in Bay Area)--use Costco Top Tier fuel (high volume station) Oil changed with Mobil 0-20W Full Synthetic every 5K miles religiously and OEM filters (indicator usually states 37% remaining at around 5k miles) 90/10 Highway/City driving Any thoughts? My MPG is seems close to normal. Lifetime average of 17, most of my time driving is short city trips or long highway driving with a bed full of gear and a dirt bike. Some of the actions seem like it could be a noise related to the vacuum pump but the pump doesn't exhibit any noises itself. Sounds kind of like exhaust leak--exhaust seems to check out (no notable soot around connections or along piping that is visible). If it was something loose, I would think that even under deceleration (letting off throttle) would cause the noise to persist. It follows increasing RPM. I've checked around the footwell and haven't noiced any plugs missing or issues there. The fact that the sound is not there when cold or after some bumpy roads makes me think something else is up. Thoughts? Things to check? When it is quiet, this truck is wonderful. The ticking in the background that comes and goes is like a form of Chinese water torture. The fact that it does go away sometimes makes me even crazier as I know it could be better. When I bought it, it did not make this noise. Only after 700 miles of driving did it begin to tick tick tick away.

Receive a notice letter from GM yesterday on failing vacuum pumps causing low speed hard brake pedal that could cause a problem in low speed braking. Their only offer in the letter is they will extend the warranty on them for 6 years from in service date the of truck or 72,000 miles in the interest of "customer satisfaction". NO recall however. They said for make sure and follow oil change intervals for this might be a contributing factor in the pumps premature failing. My thoughts on this is they should recall known safety issue parts period. Looks like GM is trying to save themselves some money on a due to fail early, weak link in their brake, vacuum system. No mention of the word "accident" in the letter anywhere of course. My truck went into service in December of 2013 and has just turned 50,000 miles so my extended warranty will be up in just 8 months or so on this obvious poorly designed pump. Thoughts anyone?

For the last 5,000 miles or so, I have noticed a (louder than normal) ticking noise coming from my engine bay. Recently. while navigating a parking garage at the airport, I lost all brake boost vacuum and almost hit a column. I did some research and found all of the info online relating to the NHTSA investigation etc. I went to my local dealership. They wanted $900 to replace the vacuum pump. It broke out as $615 in labor and $285 in parts. After looking around online, I couldn’t find a detailed write-up or video on this repair. I put together a write-up for anyone else who might want to save a few hundred bucks Be easy on me, I do a little light mechanical work but and have never done a write-up. I’m sure I screwed some things up… Supplies I Used: · Flathead Screwdriver · Plastic Pry Tool · Small Hook Pick · 3/8-in Ratchet · 3/8-in Torque Wrench · 3/8-in Drive 3-in Extension · 3/8-in Drive 6-in Extension · 1/2-in Drive 24-in Breaker Bar · 1/2-in Drive 5-in Extension · 10mm Socket (3/8-in drive) · 11mm Socket (3/8-in drive) · 15mm Socket (3/8-in drive) · 24mm Socket (1/2-in drive) · 7 Quart Drain Pan · OEM Stretch Belt Installation/Removal Tool (AutoZone Loaner P/N 27272) · Red Paint Pen · Small Bungee Cord · Medium Strength Threadlocker Replacement Part: · ACDelco GM Original Equipment Vacuum Pump -- P/N 12669488 (I bought it from gmpartsgiant for about $130 shipped) Step 1 – Prep the Workspace: Park the truck on a level surface Lock steering wheel about 1/16th of rotation right of center Disconnect the negative battery terminal Remove the plastic skid plate/shielding from below the engine compartment (four 10mm and two 15mm bolts) Place the drain pan on the ground below the vacuum pump Pull the air intake tube away from the throttle body to give access to the crank pulley from above Disconnect the two crank case vent hoses from the intake Disconnect the intake from the throttle body by loosening the clamp and pulling it back Pull the intake up and toward the passenger side. Secure it, out of the way, using a bungee cord Cover the throttle body intake with a plastic bag, secure with a rubber band Step 2 – Remove the Lower Steering Shaft With the paint pen, mark the steering shafts at the connection points between the intermediate steering shaft and the steering gearbox input shaft. This will be used for reference at reinstallation. With the steering wheel locked about 1/16th of a rotation right of center, the upper bolt (closest to the firewall) of the lower steering shaft easily accessible. Using a 15mm socket, remove the bolt. Note: The upper bolt is secured with a collared nut that wraps around the shaft. When the bolt is completely removed, you should be able pop the nut off the shaft. Moving down the shaft, there is an 11mm bolt that fastens the lower steering shaft to the steering gearbox input shaft. I was able to easily access this bolt by unlocking the steering wheel and slightly moving the wheel toward center. Remove the 11mm bolt. With both bolts removed, remove the lower steering shaft from the steering gearbox input shaft by pulling upward. Once the lower steering shaft is separated from the input shaft, slide the lower shaft down and toward the front of the vehicle to separate the lower shaft from the intermediate shaft. Step 3 – Remove the Vacuum Pump Place the stretch belt removal tool on the vacuum pump pulley. Using the 1/2-in drive 24-in breaker bar, 24mm socket and 5-in extension, turn the crank pulley until the belt slips off the vacuum pump pulley. Follow the vacuum line from the brake booster to the vacuum pump. Using the plastic pry tool, separate pressure fit fasteners holding the vacuum line in place. Additionally, remove the pressure fit fastener securing a wire loom to the pump Using the hook pick, carefully remove the retaining clip where the vacuum hose is attached to the vacuum pump. Note: There is a heatshield around this fitting the will need to be carefully peeled back. Separate the vacuum hose from the pump and rotate the hose out of the work area. Four bolts secure the vacuum pump in place. Using a the 11mm socket and a combination of the 3/8-in drive extensions, loosen all four bolts. While holding the vacuum pump in place, finish removing all four bolts and separate the pump and gasket from its mounting point. Note: About 1/4 to 1/3 of a quart of oil will leak out into the drain pan during this process. Lift the pump out while rotating it around the wire looms and belts (this will take some finagling). Step 4 – Install the New Vacuum Pump Coming from the top, rotate the new pump into position. Note: The pump I bought came with four new bolts and a new gasket. While ensuring that the gasket is firmly in place, use the 11mm socket and extensions to finger tighten the four bolts. With the 3/8-in drive torque wrench, torque the four bolts to 23 ft/lbs. Note: I called my dealership service department and was told the torque specs over the phone. I have no documentation showing the specs Rotate the vacuum hose back into location and attach to the pump. Snap the retaining clip back into place and put the heat shield back into position. Push the pressure fit fasteners back into position Using the reverse process of removal, reinstall the belt. Note: if you are reusing the same belt, be sure to check that it is in acceptable condition for reuse. Step 5 – Reinstall the Lower Steering Shaft Lining up the paint pen marks, slide the lower steering shaft back onto the intermediate steering shaft. Once the lower shaft and intermediate shaft are together, slide the lower shaft onto the steering gearbox input shaft. Apply the threadlocker to both bolts. Reinstall each bolt (15mm and 11mm) and torque to 35 ft/lbs. Note: I called my dealership service department and was told the torque specs over the phone. I have no documentation showing the specs. Step 6 – Reinstallation of Workspace Items Reinstall air intake tube using the reverse process outlined in step 1. Reinstall the plastic skid plate/shielding from below the engine compartment (four 10mm and two 15mm bolts). Connect the negative battery terminal. Check engine oil. Refill as needed (1/4 to 1/3 quart)