2014 Hard Brake Pedal At Low Speed

Spartan · November 20, 2018

I've been trying to diagnose a hard brake pedal at low speed. I'v3e read thorough many forum threads to see what the common issues are, and I've ruled out the vacuum related possibilities (i think). The hard brake pedal has only happened in low speed parking lot situations, mostly backing into a parking space, but it has happened going forward as well. The truck has 90k miles on it and this is the first issue I've had with it. The brake pads/rotors are original, and the brake fluid is also original. I have plans to get the brake fluid flushed when i do the first brake job. Currently the fluid doesn't look to dark. Its kind of the color of watered down ice tea.

Here's is what I've done so far.

vacuum pump - I disconnected the vacuum line and put a gauge directly on the pump. It pulled 27Hg of vacuum.

Brake booster - With the engine off, i pumped the brake pedal 3 or 4 times until it was hard, and with my foot still holding it down, i started the engine, the pedal sank with a little resistance. I kind of shuddered down, not smooth. Since I wasn't satisfied with that test, i disconnected the vacuum line and used a mity-vac to pull a vacuum on the brake booster. I was able to hand pump 13 Hg of vacuum and it's holding steady.

I'm starting to think this issue is not vacuum related. Is it possible it's a sensor, or something within the ABS system?

Grjfer · November 21, 2018

I pretty much had the same problem with my 2015. I would not call the pedal hard as much as I would say it took way more pedal pressure to stop. Backing up on a slight grade was worse. New vacuum pump fixed my issue.

midwestdenaliguy · November 27, 2018

Had this exact issue with my 2016, was going about 5mph in a parking lot the first time it did it. The second time it did it in my driveway as I was slowly pulling in. The pedal got firm and I had to put a TON of pressure on it to get it to stop rolling and fully brake. Vacuum pump replacement fixed it for me. An investigation has been launched by the NHTSA to determine if GM needs to do a recall on this issue. Keep any receipts you have when you repair it.

Sierra Dan · November 27, 2018

On ‎11‎/‎20‎/‎2018 at 8:53 AM, Spartan said:

I've been trying to diagnose a hard brake pedal at low speed. I'v3e read thorough many forum threads to see what the common issues are, and I've ruled out the vacuum related possibilities (i think). The hard brake pedal has only happened in low speed parking lot situations, mostly backing into a parking space, but it has happened going forward as well. The truck has 90k miles on it and this is the first issue I've had with it. The brake pads/rotors are original, and the brake fluid is also original. I have plans to get the brake fluid flushed when i do the first brake job. Currently the fluid doesn't look to dark. Its kind of the color of watered down ice tea.

Here's is what I've done so far.

vacuum pump - I disconnected the vacuum line and put a gauge directly on the pump. It pulled 27Hg of vacuum.

Brake booster - With the engine off, i pumped the brake pedal 3 or 4 times until it was hard, and with my foot still holding it down, i started the engine, the pedal sank with a little resistance. I kind of shuddered down, not smooth. Since I wasn't satisfied with that test, i disconnected the vacuum line and used a mity-vac to pull a vacuum on the brake booster. I was able to hand pump 13 Hg of vacuum and it's holding steady.

I'm starting to think this issue is not vacuum related. Is it possible it's a sensor, or something within the ABS system?

Hopefully in all of your cases...…… the Vacuum Pump did not grenade metal shavings into your engine oil or engine, as it is lubricated by engine oil.

tsmith6 · January 10, 2019

I had the exact same issue on my 2014. Granted i did not check vacuum but with a little extra rpm's the problem quickly went away. Knowing what I know now I would suggest getting that POS original design off of your truck before it begins to leak oil into the vacuum line and you need to replace $700 of parts instead of the $120 part. If you have concern over which part you have, the parts shop at a GM dealer can verify which part number is on your vehicle the old(12659655) or new(12669488) with your VIN number. The part is definitely different than my original indicating some substantial changes, and will hopefully not have the same problems as the original. I did notice even with the new pump at 700 rpm the truck can lock the brakes from 5 mph as it should, however still at 450-500 rpm I cannot lock up the brakes due to lack of sufficient vacuum, however it does stop significantly better than it did with the old pump. With the old pump the problem was most pronounced for me with my boat on the back barely moving in the driveway (medium grade) and the most recent trip to the boat ramp. On several occasions i noticed it took 2-3 times as far to stop as usual, but only at idle engine speeds. Hopefully GM will see this should be a recalled part so save your receipts and be especially careful backing in boats and stopping on grades with trailers especially if they do not have trailer brakes. Best of luck!

Marek MD · February 4, 2019

Yes my 2015 same problem mostly going backwards

Obscenejesster · February 14, 2019

My 2016 went in today for the same issue. They replaced the vacume pump and it fixed it. I also no longer have a loud ticking noise under the hood.

Ben S · November 4, 2019

I am having this same issue on my 2015 Silverado Crew Cab. Would anyone think the vacuum pump would be covered under powertrain warranty?

Edited November 4, 2019 by Ben S
Grammer

Brendan1911 · November 7, 2019

I just received a recall notice the other day. Haven’t had the problem, but the notice literally said that there’s an issue with the vacuum pump where over time, it weakens so that at lower speeds, it’s less effective. Apparently there’s some hydraulic assist or something that’s only programmed to work sometimes. The recall involves the dealer reprogramming it so the assist picks up the slack. I’m sure I’m not explaining it perfectly, but after getting the notice and seeing this, I bet it’s your problem. I’ve never had the issue myself.

Sierra Dan · November 7, 2019

On 11/3/2019 at 8:33 PM, Ben S said:

I am having this same issue on my 2015 Silverado Crew Cab. Would anyone think the vacuum pump would be covered under powertrain warranty?

There is a special coverage warranty on the Vacuum Pump.

For 6 years or 72k miles as long as the dealer confirms that the Pump as bad.

Edited November 7, 2019 by Sierra Dan

Ben S · November 12, 2019

I had an appointment today to get the pump replaced. The work is going to be covered however, the pump is on back-order with no known lead time. They also deemed my vehicle "unsafe" to drive yet GM will not pay for a rental in the meantime. Gotta love GM!!

onedash · November 13, 2019

Just got a letter saying the extended warranty for this issue has been bumped up to 150K miles. Submiting for reimbursement for my vac pump I had to pay for.

rmichaelson · November 25, 2020

I have this issue on my 2015 Silverado Crew Cab. Call the dealer, they should be covering this under a special warranty on the vacuum pump...up to 10 years, 150k miles.