Ram 1500 5.9 Magnum has no brakes whatsoever. Had the issue, thought it was the booster, replaced it, still has the same problem. Vacuum is good, lines are good, no leaks in brakelines. Truck has n o braking power at all. Pedal gets hard when truck is off or when truck is on with vaccum lines disconnected. Completely soft when truck is on with lines connected. Has no braking power either way.

Any ideas on what could cause this?

 

Sounds like the master cylinder is giving up. Someone with more knowledge will probably chime in soon.

 

Done any brake work recently?


Bled the lines really well?

 

Other than putting in the new booster no real work as been done recently. I did try to bleed the line but the bleeders are mush and locked up.

 

I did release air and fluid through the junction block in the rear axle though.

 

Have to be able to bleed the system to diagnosis this issue. It could be as simple as air has gotten in your system.

Maybe from a leaking, going out master cylinder but if you can't bleed the system it doesn't matter. Even if you replaced it.

The proper way to bleed the whole system is to start at rear passenger then rear driver, than front passenger and finally driver side front.

 

Start soaking your bleeders with PB Blaster, or something similar. (not WD-40, that won't cut it.) Going to have to do that several times over a couple days, and see if you can get them to break loose. If not, replace the calipers, and wheel cylinders. (wherever you cant get the bleeder open.) THOROUGHLY bleed the system. Should get your brakes back.

I would also wager that the line going over the gas tank is indeed leaking, its just not making it to the ground yet..... follow that line end to end, see what you find.