Okay, the protective coating is a fallacy. There is nothing coated on the disc brakes only new ones that you get in the mail out of the box.
Now you have to remember you have ABS andtraction controlon this vehicle. I am not positive but from experience the Power Steering pump provides pressureto the hydraulic booster to the brake system. Note, years ago and maybe still on some vehicles today you had/have a Vacuum Booster ergo vacuum from the engine to increase the pressure for your "Power Brakes" that big round tank behind your master cylinder. This assisted in giving the extra force or pressure to the brake system to stop the vehicle better. Now with ABS you needmore pressure and it needs to be constant to provide you the rapid pulsations(electronically controled/monitored by the wheel sensors)during sudden stops, because you could never push your foot fast enough to mimic that function.
So now your brake system is more complex and requires that needed force/pressure tooperate your ABS. So now if your PS fluid is low it will effect your brakes (if you have a hydraulic booster), if your belt is slipping on the PS pump/engine for a split second you will feel a pressure loss. If you look under the hood at the master Brake cylinder area and if you see the big round tank you have Vacuum assited brakes. If you have a cylinder the size of a FOSTERs beer can or Coke Canyou have hydraulic assited or Hydro Boost which is supported by the PS pump. That is why your brake pedal sinks and comes back because your pressure is building up could have a faulty Dump Valve, Spool Valve, leaking piston seal or small leak in the hydraulic hose. This is just from my basic experience with this observation.

 

Like I said before in my post... if it always did it... or just started doing it... that isn't right... if the engine is running there should be enough vacuum or pressure depending on the systemon any make or model to hold the brakes...

 

Okay, you have now convinced me there is a potentialissue here & will call the dealer tomorrow for an appointment.

Thanks for all of your advice

 

The brake pedal will go down much further than normal before the engine is running or within a second or so of starting the engine. Most people start there vehicles with there foot off the brake so they don't notice it. When I got in my loner this morning I took notice and it did it just like mine. This is pretty common on modern vehicles.

As for the brakes locking up, take a close look at the rotor after it has sat for a few days, or even over night if its humid. You will see small orange specks on the worn surface.... it's rust. When the pads hit it they lock up. Once again driving habits (along with your environment) play in to if you notice this or not. If you have an automatic transmission and back out of your driveway by releasing pressure on the brake, then you rub the rust off. If you have a manual transmission, it's a bit harder to start moving and have your foot on the brake to rub the rust off. You get a little speed and gently apply the brakes and they will lock up.

Take it to the dealer if you like, you definitely don't want to be driving it around if there is a problem, but don't be shocked when they say it is acting normal.

 

My h3 is now ok....the brakes were doing what you described, but now that I have driven it, the brakes are normal....they do not go to the floor or grab anymore.....all my other vehicles have always grabbed when they formed rust on the rotors, but the going to the floor bit unusual....hope your dealer takes care of you!