[DenverTaco07]

makes perfect sense to me...thx!

[mbar]

Originally Posted by bybcous

They replaced my master cylinder when this happened to me awhile ago

Did you have the warning light come and go several times. Did it just stay?
Do you remember what did the diagnostic tool said?
Thanks

[gw6211]

Originally Posted by mbar

I would not look at it as free....I paid for a car that has a warranty.

....that you worked on. If you messed it up then its your baby, hence, time to pay

[77Z28]

I had it happen to me with the stock pads when I was backing into a parking space. When I came back out to leave the brakes were fine. That was over a month ago and it has not happened again.

[Tushar]

Same code came up for me some time ago. Shut off the car, waited for 5 mins, turned it on again. All good.
It may be something to do with Low Voltage.

[mekirk2]

Originally Posted by gw6211

....that you worked on. If you messed it up then its your baby, hence, time to pay

This is like saying that they should charge you to diagnose a check engine light because you changed your own oil and filter.

So changing brake pads causes them to not be responsible for the braking system?

I call bs....

[Moc96]

Originally Posted by mekirk2

This is like saying that they should charge you to diagnose a check engine light because you changed your own oil and filter.

So changing brake pads causes them to not be responsible for the braking system?

I call bs....

Especially with how incredibly easy changing the pads on this car is. Unless you're "special", you can't mess it up.

[mbar]

Update:
Car just came back from the dealer. Scan tool found 1 time code C025E - brake booster vacuum sensor. They drove the car around and code did not reproduce the code. They said it was a one time code and it's all good...

Thanks for everybody's help!

PS- I should go check my tires to make sure they did not do too many burnouts

[mekirk2]

Originally Posted by Ole No. 1

My 2016 2SS did this a couple weeks ago. As soon as I started it up i got the "Service Brake Asssist" warning. Drove out the driveway and the pedal felt a little like the ABS was pulsing although I don't think it was. The car stopped fine... just had longer travel of the brake pedal. I got to my destination in about 5 minutes. Shut the car off, went in to eat dinner. Came back out and all was fine. Haven't had the issue since.

I chocked it up to a weird electrical gremlin...

Had this same thing happen today. I had been listening to the radio with the ignition on for a little while before it happened. Exactly like yours did.

[camaro5]

Here's a great clue...Sticky vac sensor

Originally Posted by mbar

Update:
Car just came back from the dealer. Scan tool found 1 time code

C025E - brake booster vacuum sensor.

They drove the car around and code did not reproduce the code. They said it was a one time code and it's all good...

Power Brake Booster Replacement


The vacuum in the brake booster assembly is measured by the brake booster vacuum sensor.

The Engine Control Module (ECM) supplies a 5 V reference and a low reference circuit to the brake booster vacuum sensor.

The vacuum sensor supplies a voltage signal in relation to the pressure in the brake booster to the ECM.

To address this condition, install a new power vacuum brake booster.

Do not replace the ECM or power brake booster vacuum sensor.

YMMV

[m666etal]

Originally Posted by 77Z28

I had it happen to me with the stock pads when I was backing into a parking space. When I came back out to leave the brakes were fine. That was over a month ago and it has not happened again.

That is exactly what happened to me today! Feels scary if this were to happen on the freeway or at a sudden stop.

[BJCO23]

Originally Posted by mbar

Replaced my front brake pads (Carbotech XP10) with new Carbotech XP12 ( one step up in aggressiveness ).
Test drove it and did pad bed in yesterday. All went well.
This morning after 5 miles of driving, got a warning light 'Service Brake Assist' and the brake pedal stared vibrating with every press.
Already tracked my car several times with the previous XP10.
Thanks for your help.

Got code and issue this past Friday morning. Took it to dealer same day, they communicated issue to GM they replied back telling them to do an update to the system they did and error cleared. Car was then driven twice, 4 miles each, and problem gone. No issues again, so far.

[CowmaroV8]

I just experienced this issue and thanks to checking in the forums here had it taken care of with a service bulletin. I understand this is an old forum, but with low mileage cars still out there, this issue is still very real in 2020 and I wanted to help anyone I could.

My brake assist warning came on and I lost about half my braking pressure and it felt that ABS was on 100% of the time. This is mentioned in the owners manual as normal behavior when the service message occurs.

I turned the car on the next day and the issue was gone but took it for service anyway. They told me there was a service bulletin and they will simply run a diagnostic and if no issues are found other than the TSB then that's all they will charge. It happened 8 hours prior the night before the computer had all the error codes stored so they were able to pull them up without any active CEL or Error Codes.

Should be a recall and not a TSB but just needed to share this as these forums are the reason I knew of the fix ahead of time. Maybe a diagnostic fee is worth the piece of mind to get the update needed rather than waiting for the brakes to fail in traffic as mine did.

"Internal software fault in EBCM. Reprogram EBCM per BULL#17-NA-048"