Master cylinder keeps running low on fluid
Walk around the car and check for one of the tires to look different then the other 3 ... it sounds like one of the brake cylinders is leaking. When that happens the centrifugal force throws the fluid to the outer part of the tire .... sometimes it's on the inside so you may have to stick your hand on the inside of the tire. I'm assuming you looked around the cylinder itself for a leak.
Search Dodge Ram 1500 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Dodge Ram 1500 Experts