Loss of brakes after putting truck in reverse

cjmiller · February 27, 2018

Searched and didn't find anything on this. Starting today my truck losses braking ability after I put it in reverse. Brakes work fine going forward but after I put the truck in reverse to back into a parking spot the pedal goes to the floor and braking ability is almost non-existent. Have been able to duplicate the problem both of the times I have tried to backup since.

Any ideas?

2016 Sierra 1500

Justin101714 · February 27, 2018

So while backing into a space with your foot mostly on the pedal, easing yourself into the spot sort of feathering the brake pedal.....that will drain the vacuum in the booster. The vacuum pump doesn’t keep up. See about having the vacuum pump replaced, there is a new design out. Make sure no engine oil is in the vacuum pump tube from the booster to the pump. If there is oil, it’ll need a booster, the line and the pump.

Sent from my iPhone using Tapatalk

Logan Lanfear · February 27, 2018

7 minutes ago, Justin101714 said:

So while backing into a space with your foot mostly on the pedal, easing yourself into the spot sort of feathering the brake pedal.....that will drain the vacuum in the booster. The vacuum pump doesn’t keep up. See about having the vacuum pump replaced, there is a new design out. Make sure no engine oil is in the vacuum pump tube from the booster to the pump. If there is oil, it’ll need a booster, the line and the pump.

Sent from my iPhone using Tapatalk

The pedal wouldnt sink to the floor if he lost vacuum pressure. I would do the opposite and be harder to push.

Justin101714 · February 27, 2018

Don’t understand why reverse matters? The brake pedal should be the same whether it’s forward or backwards....the complaint boggles my mind

Sent from my iPhone using Tapatalk

Logan Lanfear · February 28, 2018

3 minutes ago, Justin101714 said:

Don’t understand why reverse matters? The brake pedal should be the same whether it’s forward or backwards....the complaint boggles my mind

Sent from my iPhone using Tapatalk

It sure is an interesting problem. Hopefully someone has an idea. There are a lot of folks out there with these year trucks.

Justin101714 · February 28, 2018

OP, try a parking maneuver while going forward and see if it does it

Sent from my iPhone using Tapatalk

cjmiller · February 28, 2018

did some more backing up and going forward, I was incorrect stating that the pedal went all the way to the floor, it does travel a bit but then it won't move any further and braking is very difficult. I guess because it pushed in and then stopped so hard I was thinking it was going all the way to the floor but it isn't.

Sounds like it may be a vacuum pump issue? dealer asked if I had any aftermarket modifications, truck has a front leveling kit. Somehow I imagine they will say that caused the issue??....

Logan Lanfear · February 28, 2018

So with that info I definitely retract what I said before about it not being a vacuum issue. It sounds like you lost the "power" out of your power brakes.

Donstar · February 28, 2018

14 hours ago, Justin101714 said:

Don’t understand why reverse matters?
Sent from my iPhone using Tapatalk

I thought you gave a great explanation in your previous post! "So while backing into a space with your foot mostly on the pedal, easing yourself into the spot sort of feathering the brake pedal.....that will drain the vacuum in the booster."

Justin101714 · February 28, 2018

So, have the pump replaced, inspect the line from the pump to the booster for oil intrusion, if okay, only replace the pump, if there’s oil, replace the booster, the line and the pump. Check oil level as well. It is a new design and functions better. I’ll have to do mine soon as it’s starting to make noise.

Sent from my iPhone using Tapatalk

Bigd1 · April 3, 2018

This just happened to me today. 2016 Silverado LTZ 40,000 miles. Backing into a parking spot brake pedal got hard as a rock. It happened when in put in forward too. I put truck. In neutral and raised rpm and power brakes came back. I hope it will be ok driving home ?. So from what I’m reading there is a TSB for this. But it looks like GM will not cover under the 50k drive train warranty. Looks like pump, booster, and hose should be replace looks like under $250 in parts. I have mechanical break down coverage under geico but I think my deductable is $500. What do you guys think. Check hose for oil and if no oil just pump if oil replace booster and hose too. BTw mine has been ticking

Boardmember · April 4, 2018

I had this issue (with another or three) with my first ‘16. Repeated visits. It’s finally what caused me to trade it. I told the dealership it was endangering others, me and my employment if it occurred when I was in the service of my employer.

OP is NOT making this up.

Edited April 4, 2018 by Boardmember

sk · April 5, 2018

I had this problem 2 times since I owned the truck. The last time the dealer still couldn't replicate the problem but I talked them into replacing the parts. As Justin said the pump is a new design with some extra baffles in it. The brakes felt a little different after the update (not worse or better, just different) and so far it hasn't done it again.

An interesting side note -- I was having the loud ticking that everybody complains about and numerous dealers said it was the DI noise. They replaced the vacuum pump for the brake issue but I have not had the ticking noise since!

Tell them to look up Bulletin PIT5361B.

Edited April 5, 2018 by sk