My system is wired so as the brake lights come on when I press the RV brake pedal, when my car brake system is not installed.
However, since I use a diode pack, when my brake system is installed, brake pedal is push, brakes lights will come on. So, it all depends on how you wire your system.
As an extra, my third brake light ONLY comes on when the car brake pedal is depress.
Dale&Susan, 08 Alfa Gold, DaGirlsRv,
KoKo(Rainbow Bridge)&Della(Rainbow Bridge) 08 Jeep Liberty_Solar_940W Solar_660 AmpHr