A Really Odd Brake Issue

[David Williamson]

Sometimes when I press the brake pedal to start the engine on our '24 GV70 3.5 V6 the pedal goes to the floor! It has happened 6 or 7 times over the last month or so, seems to be after the engine is hot and was shut off for 10 or 15 minutes. It has never happened while driving only at start up. The pedal feels normal and then it "clicks" and goes to the floor, after releasing it is normal. It is like a relay or valve is opening and the brake fluid is bypassing the master cylinder. Are these cars brake by wire? Anyone else have this issue? It is going in next week and I expect to hear "we can't make it do it so don't know what to do" I hope they know what to do but, we will see. I plan to put a note in the car explaining it for the tech to read. I have been working on cars for over 40 years including building 2 and this is a new one.
David W

 

[David Williamson]

Well the dealer tech checked it out, scanned for codes etc. and found nothing wrong. The GV70 and I suspect most of the other Genesis line use "brake by wire" what that means is the computer is doing the braking based on how hard you push on the brake pedal and how far the pedal travels. The tech thinks it was a computer glitch.
David W