The rear brakes are disc, but when i first tried to bleed them the rear brakes didn't even work , there was alot of air in the system but from normal bleeding there is straight fluid coming out and there are no leaks. What is a high line scanner and can i do it myself or should i take it to a shop. Also the rear brakes are working now but the pedal goes all the way to the floor. When the truck is turned off though it will build pressure.