2015 Tahoe LTZ - intermittent brake assist loss at low revs - vacuum pump??

[2015LTZ]

Hi everyone,

Need help with diagnosis a problem. I have 2015 tahoe LTZ with 100,000 miles. Recently i have observed that the brake pedal becomes hard at low rpms when i'm in slow moving traffic. and i believe the ABS also engages momentarily when this happens. This goes away quickly but has been happening for the past 3 or 4 days. I have also started hearing a ticking noise from the front left side of the engine bay.

Could it be the vacuum pump going away? if it is, whats the part number and what else should i change with it?

 

[Tonyv__]

I have the same issue in my 2015 Yukon. I’m fairly certain the brake booster was a common issue. I have not done anything to try to correct it yet but I’m following now to see what others say.

 

[OR VietVet]

More Information for GM GENUINE 12696313

Well, could be the pump, especially with the ticking noise at left front of engine bay. The booster is back at the firewall.

Have you checked the belt and made sure is in great shape and tight? That could be the source of problem and the noise.

 

[2015LTZ]

More Information for GM GENUINE 12696313

Well, could be the pump, especially with the ticking noise at left front of engine bay. The booster is back at the firewall.

Have you checked the belt and made sure is in great shape and tight? That could be the source of problem and the noise.

So the booster and the vacuum pump are two different things right? I am assuming the booster is fine and its the pump thats going. The belt seems to be in good shape. But I will change it regardless.

 

[OR VietVet]

So the booster and the vacuum pump are two different things right? I am assuming the booster is fine and its the pump thats going. The belt seems to be in good shape. But I will change it regardless.

The belt may be in good shape but is it tight as should be. The noise at front of engine is also a trigger. The vacuum pump is to supply vacuum to the brake booster.

 

[2015LTZ]

The belt may be in good shape but is it tight as should be. The noise at front of engine is also a trigger. The vacuum pump is to supply vacuum to the brake booster.

Got it. So you're suggesting tightening the belt first before replacing the pump?

 

[Doubeleive]

did any of you have the recall done? there is software update for this issue.

 

[2015LTZ]

did any of you have the recall done? there is software update for this issue.

Yes i was called by the dealer to get some software update done for the abs module. I got it done

 

[2015LTZ]

did any of you have the recall done? there is software update for this issue.

Do you suggest getting the vacuum pump changed or not? The issue is not that frequent. But when it happens in traffic its alarming

 

[Doubeleive]

Do you suggest getting the vacuum pump changed or not? The issue is not that frequent. But when it happens in traffic its alarming

there is another known issue of the vacuum pump seal going bad and allowing oil into the brake booster that can cause a problem and yet another issue where the booster seal can leak
there is a service bulletin for the booster leak

https://static.nhtsa.gov/odi/tsbs/2016/SB-10081053-2280.pdf

there is a 10 year special coverage on the vacuum pump "if" IT fails diagnostics and or throws a "service brake assist" in the dic therefore setting a code.
https://static.nhtsa.gov/odi/tsbs/2019/MC-10167479-9999.pdf
I would pull the vacuum line off and check if there is fluid inside or if it is dry

If the vacuum pump fails diagnostics it's free under the special coverage for 2015-2018 for 10 years