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2018 Traverse Redline over 36,000 trouble free kilometres

After parking vehicle for a few days (3-4), I experience very little brake boost when depressing the brake pedal to start the vehcile. I have to pump the brakes a few times to start the vehicle.

Anyone experiencing same issue?
 

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Brake booster check valve could be leaking or booster itself.
 

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Took my 18 high country back to the dealer with the same issue. Mine does it sitting overnight and started shortly after buying it new. The dealership made a work order on it and called engineering at g m. 11000 miles later I still don't have an answer.
 

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After parking vehicle for a few days (3-4), I experience very little brake boost when depressing the brake pedal to start the vehcile. I have to pump the brakes a few times to start the vehicle.
I'm not certain that I understand the issue exactly, but I have experienced some instances where the brake pedal is so hard to push, while the engine is off, that it does not travel far enough to make the switch allowing the engine to start. I have to press on the brake pedal really hard in order to get the pedal down far enough to be the engine started.

I can almost replicate this by pressing the brake pedal a couple of times after the engine has been turned-off. The brake pedal gets really hard to depress.

Is what I am experiencing the same as what is happening to your?
 

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Discussion Starter #6
I'm not certain that I understand the issue exactly, but I have experienced some instances where the brake pedal is so hard to push, while the engine is off, that it does not travel far enough to make the switch allowing the engine to start. I have to press on the brake pedal really hard in order to get the pedal down far enough to be the engine started.

I can almost replicate this by pressing the brake pedal a couple of times after the engine has been turned-off. The brake pedal gets really hard to depress.

Is what I am experiencing the same as what is happening to your?
Yes, that's a very good description of my experience.
 

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The reason for a hard pedal is that vacuum assisted brake booster is not storing it's reserve vacuum when engine is off. That's why brake pedal gets harder to push.
It normally should have at least one or two ''normal'' pedal actuations in reserve. This applies to any power assisted brake vehicle.
 

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Yes, that's a very good description of my experience.
Same goes with me
My driveway is sloped, after I pull into the driveway, my foot is on the brake when I place the car in park. Before taking my foot off the brake, I apply the “parking Brake” so the car doesn’t roll back against the transmission parking pawl when I remove my foot from the brake.

Although I haven’t tried this yet, I suspect that there are times when I turn-off the car before taking my foot off the brake. This may cause the brake system from accumulating the brake vacuum mentioned by RepairMan54 and causes the brake pedal to remain hard to push when you try to start the car again..

I’ll have to give it try to see if I can recreate it. I let you know how my result later.
 

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Although I haven’t tried this yet, I suspect that there are times when I turn-off the car before taking my foot off the brake. This may cause the brake system from accumulating the brake vacuum mentioned by RepairMan54 and causes the brake pedal to remain hard to push when you try to start the car again..

I’ll have to give it try to see if I can recreate it. I let you know how my result later.
Turning engine off with your foot on the brake should not affect the brake boosters reserve capacity. It still should have enough reserve for one or two applications.
If still under warranty take it in as it is not normal. If you have a second vehicle in the household you can see how it operates by applying the brakes in it with engine off.
All power brakes systems are like this as if engine stalls normal assisted braking is retained for a couple stops.
 

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Turning engine off with your foot on the brake should not affect the brake boosters reserve capacity. It still should have enough reserve for one or two applications.
Agreed!

you can see how it operates by applying the brakes in it with engine off.
All power brakes systems are like this as if engine stalls normal assisted braking is retained for a couple stops.
Also agree. I used to teach that years ago to my students.

Just thought that maybe something weird was happening when shutting off the car.

Tried to replicate the issue this morning but could not... exactly.

The only way to make it work was as you said Repairman: with the engine off, pump the brakes a few times and the pedal with get really hard and barely move.

In my case, since it hasn't happened in some time, I'll wait before taking it to the dealers.

For the others to whom it occurs, do you have any kids that could be playing in the car and pushing on the brakes? (just a thought)
 

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The dealership replaced the check valve and hose. It's still not right so it goes back next week.
Step 2, looks like booster surgery. Not common to fail unless your have a Rav 4
 

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2018 Traverse Redline over 36,000 trouble free kilometres

After parking vehicle for a few days (3-4), I experience very little brake boost when depressing the brake pedal to start the vehcile. I have to pump the brakes a few times to start the vehicle.

Anyone experiencing same issue?
[/QUOTE

I am writing this with the understanding that you depress the brake pedal before you start the vehicle? Is that correct? If you haven't started the vehicle in a few days, it's natural for the vacuum to be gone. Don't depress the pedal when starting, let the engine idle for a few seconds to build up vacuum then try it. Then if you don't have good brake boost you have a problem. There's no need to step on the brake until it's time to put the vehicle in gear.
 

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I had this a while ago especially after cold soak - dealer said this is normal operation.
 

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Just pulled my '20 out of the garage after 12 days, plenty of brake boost and reserve in it.
 

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Well my 18 has been at the dealership for a week and engineering told them to change out the vaccum booster unit. I must say my dealership has been excellent throughout this process and letting me have a 2020 blazer to drive for the week. Hopefully this will be the solution. Should pick it up tomorrow.
 
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