I despair slowly!!!!! With our Actros MP3 1846 2012 2-axis the brakes get very hot at the rear, sometimes it smokes. It was read out with StarDiagnose however there is no error code. Very often have pressure in the combi cylinder although I do not brake. I then tap very easily on the brake pedal it is for a short time away the pressure. I have already driven with manometer. With inserted parking brake comes sporadicly light air from the vent from the modulator.