Service Brake Assist? - SOLVED

[genestoy]

Every time I start my new 2026 Yukon AT4 I get the "Service Brake Assist" showing on the DIC...took it to the dealer two days ago and they did a software update and said the battery was defective so replaced it. Got it home fine started it a couple of times no more message...drove it today 100 miles away from home, stopped for lunch and it has started in again on every start the warning message appears. Anybody with a late model have this happen all the time and if so what was the fix?
Thanks

 

[genestoy]

Took the Yukon back to the dealer today, they gave me a rental car, will see what they say this time

 

[mortten]

Had that message come up on a 2011 Lacrosse when the magnet fell of the left rear wheel bearing but all the other associated lights came on.

 

[Foxguy1973]

Every time I start my new 2026 Yukon AT4 I get the "Service Brake Assist" showing on the DIC...took it to the dealer two days ago and they did a software update and said the battery was defective so replaced it. Got it home fine started it a couple of times no more message...drove it today 100 miles away from home, stopped for lunch and it has started in again on every start the warning message appears. Anybody with a late model have this happen all the time and if so what was the fix?
Thanks

Check the firewall grounds. They can resolve a multitude of issues

 

[genestoy]

It is at the dealer and I believe they are replacing the master brake cylinder and the module, supposed to be ready by tomorrow

 

[genestoy]

Picked the Yukon up this afternoon...It was the master cylinder and was replaced with the newer updated one...these master cylinders are a complete unit including the electronic module and the reservoir. Then all the lines had to be bled. Then the software had to be updated which took 2-3 hours. So far no more Service Brake Assist warning in the DIC. My advisor told me that they had already replaced a few of these so had the new master cylinder in stock. GM has known about this problem for some time now so don't understand why a 2026 vehicle built late March was shipped with a known defective master cylinder?