Brake Power Assist Failing at Parking Lot Speeds

[WillCO]

I have a brake issue I want to run by you guys.

2016 Tahoe LT, about 86K miles.

Occasionally when I am at the end of a journey, either long or short, something fails or deactivates in the power assist for the brakes when I am moving the vehicle slowly into a parking position. I feel a change in the pedal feel, it seems to mash further down, and I have to apply dramatically more pressure to achieve stopping power.

The issue resolves when I turn the vehicle off and restart it, even with no delay. There are no warning lights or error messages. No visible issues with the brake hardware.

The issue never occurs at speed, thankfully as it would be very dangerous if it did. It only seems to happen when I'm inching the vehicle forward or backward slowly, as I do for instance when coasting it into the garage.

I've had the vehicle from new and it's always happened, maybe once a month or so. I haven't been able to draw any pattern between characteristics of the drive and this happening at the end of it. It might happen at the end of a 2 hour drive down from the mountains and it might happen after a 2 mile drive from the grocery.

Anyone experience this?

 

[Tahoe14]

There was TSB concerning the brakes, maybe a brake booster leaking down issue should be easy to find with a Google search.

 

[OR VietVet]

So, you have owned 6 years, since new, with this problem and did not take to dealer, under warranty, about this safety problem or you did take to dealer, under warranty, and are not sharing the info you received from them, in this post? Or am I reading this wrong? Also, sounds like the power brake assist booster is having a problem or the check valve that plugs in to the booster or you have an intermittent vacuum feed problem from engine or a vacuum pump. If I read this right, the pedal feels like it would if you were moving the vehicle, without the engine running, and you apply pressure at the brake pedal to stop the forward or backward motion?

 

[WillCO]

So, you have owned 6 years, since new, with this problem and did not take to dealer, under warranty, about this safety problem or you did take to dealer, under warranty, and are not sharing the info you received from them, in this post? Or am I reading this wrong? Also, sounds like the power brake assist booster is having a problem or the check valve that plugs in to the booster or you have an intermittent vacuum feed problem from engine or a vacuum pump. If I read this right, the pedal feels like it would if you were moving the vehicle, without the engine running, and you apply pressure at the brake pedal to stop the forward or backward motion?

Does that affect how you answer or what the problem might be?

I haven't been able to recreate it for a service tech; maybe that's happened to you at some point. The way internet forums work is we come here and post our experience to see if any others have comments or may recognize it. Anecdotally.

But yes, the behavior is more or less as you describe. When it occurs.

 

[Doubeleive]

Does that affect how you answer or what the problem might be?

I haven't been able to recreate it for a service tech; maybe that's happened to you at some point. The way internet forums work is we come here and post our experience to see if any others have comments or may recognize it. Anecdotally.

But yes, the behavior is more or less as you describe. When it occurs.

there is a recall for some vehicles for the software to correct this or a very similar issue, if it is not that then it is likely either the vacuum pump or the brake booster. Being it is intermittent you might have to just replace a part and cross your fingers, I would go to the dealer and have a little pow-wow around the engine bay with the SERVICE MANAGER as they are usually the most knowledgeable, I wouldn't try to push it as a warranty issue unless you have some kind of extended warranty if not then just pick there brain and decide what is the best choice moving forward.

 

[OR VietVet]

Does that affect how you answer or what the problem might be?

I haven't been able to recreate it for a service tech; maybe that's happened to you at some point. The way internet forums work is we come here and post our experience to see if any others have comments or may recognize it. Anecdotally.

But yes, the behavior is more or less as you describe. When it occurs.

In some cases here, others may not care about the WHOLE story, but I do. YOU made the statement that it had been going on since new. I personally want to know what the dealer told you, if in fact you did take it to them. You never said that. You skipped over that. ALL info is important. Maybe, just maybe, the recall that @Doubeleive talks about was discussed with you, by the dealer, but you did not say and that info could be important to how at least I respond, because yes, I do know how internet forums work and info is key and not the lack of it. I am not at the rig, you are, you own it, ALL related info during your ownership is important, not just the info YOU think may or may not be important.

So, I will bow out now, so as not to waste your time with my frivolous questions or unwanted digging for facts. Good luck.

 

[WillCO]

In some cases here, others may not care about the WHOLE story, but I do. YOU made the statement that it had been going on since new. I personally want to know what the dealer told you, if in fact you did take it to them. You never said that. You skipped over that. ALL info is important. Maybe, just maybe, the recall that @Doubeleive talks about was discussed with you, by the dealer, but you did not say and that info could be important to how at least I respond, because yes, I do know how internet forums work and info is key and not the lack of it. I am not at the rig, you are, you own it, ALL related info during your ownership is important, not just the info YOU think may or may not be important.

So, I will bow out now, so as not to waste your time with my frivolous questions or unwanted digging for facts. Good luck.

I do appreciate the time you took to respond. Candidly though, your attention comes with a condescension tax I'm not willing to pay. To wit, you haven't made any suggestions - you've just told me all the ways my question was poorly conceived.

Your advice hasn't been valuable enough for me to want to deal with your tone. So - best luck if we don't talk again.

 

[Fless]

To me it sounds like the ABS might be kicking in.

 

[WillCO]

To me it sounds like the ABS might be kicking in.

That is how it feels to me, now that you mention it. I feel that ABS vibration. Thanks - that gives me something to take back to the tech that I hadn't thought of before.

 

[WillCO]

To me it sounds like the ABS might be kicking in.

A little quick research, it does appear there is a common issue with Chevy trucks where the ABS engages at low speeds where it should not.

This video goes beyond my technical reckoning but appears to address the problem. I will use this information to explore with my mechanic. Thanks for the suggestion.