I have a 2006 Dodge Ram 1500 I replaced the master cylinder front and rear brake calipers and bleed the brakes I have fluid to front brakes no fluid to rear what do I do

Continue bleeding process. Make sure to keep master cylinder full. If it sucks air you will have to start over.

Hi there is a couple of things that might be happening you said that you replaced the master cylinder ...// did you bleed the master cylinder ?? if not try that as well as bleeding the brakes from the farthest point in other words start from the right rear then the left rear then right front and finally the left front ...also try bottle bleeding the system...take a bottle fill it a 1/4 way with clean brake fluid get a piece of 1/4 in hose about 15" long and open the bleeder put the hose on the bleeder and the other end in the bottle submerged in the fluid and then just pump the pedal ...you will not need to close the bleeder because it will not be pulling air but fluid see the pick I added below ...also if you have ABS (antilock brake system ) on your truck that will have to be bleed as well ...// you will need a scan tool to do that how ever ...with the scan tool the internal dump valves wil be cycled to get the air out of it....and then you will need to bleed the base brakes again as well

You may have to pump it an insane amount of times. When I put in my master cylinder I "Bench bled" it and had to pump it at least 100 times until one valve sealed and quit pumping air. After that it was an easy installation