2003 Ram 1500 - Brake Pedal Goes Down Over Time - Please Help

[HandyCruiser]

I have a 2003 Dodge Ram 1500 2WD Quadcab 4.7 V8 with 260,000 miles. It has 4-wheel disc brake and rear-wheel ABS. There are good pads on the back, new pads on the front, new master cylinder and the fluid has been flushed twice, three weeks ago. The system has no leaks whatsoever. Fluid is still full and looks brand new, like lemon aid.

When stopping at a stop sign or red light for a period of time, the brake pedal will lose tension and begin going down slowly. If I don't increase pressure on the pedal with my foot when stopped, the truck will sometime begin to roll forward after about 30 seconds. This issue is unnoticeable other times during normal driving.

I'm not sure what else to try to solve this. Changing the master cylinder did not help. And I flushed the system using an air-powered vacuum device that seems to pull a solid stream of new fluid from each wheel. If there is air trapped someplace, I do not know where or how to remove it. Everything seems perfect. But the problem persists even after the new master cylinder and flush. Please help.

 

[Daw14]

Might be your master cylinder has developed an internal problem.

 

[HandyCruiser]

Might be your master cylinder has developed an internal problem.

That's what I thought, so I replace it per my write-up above. It did not fix the issue.

 

[Oliver Closehauf]

So read some of the similar threads at the bottom of this page. It sounds like the dump valve of the rear ABS unit.

 

[BadHemi2014]

Brake booster?

 

[slowindown]

Dump valve in the abs unit (where the abs valves are( probably. See my thread below “weird brake problem, pedal drops…” Fairly simple to diagnose once I figured it out and not that difficult to replace.

Weird brake problem, pedal drops but more 2007

This will be a bit long but there's a good bit of info for troubleshooting purposes. I have a 2007 ram 1500 4 door 2wd 5.7 with 230,000 miles. I bought the truck new. Until now, no one has touched the brakes but me and that was at least 100,000 miles ago when I replaced front hubs, rotors and...

www.ramforum.com

 

[aheeejd]

Maybe the ABS sensor

 

[HandyCruiser]

Dump valve in the abs unit (where the abs valves are( probably. See my thread below “weird brake problem, pedal drops…” Fairly simple to diagnose once I figured it out and not that difficult to replace.

Weird brake problem, pedal drops but more 2007

This will be a bit long but there's a good bit of info for troubleshooting purposes. I have a 2007 ram 1500 4 door 2wd 5.7 with 230,000 miles. I bought the truck new. Until now, no one has touched the brakes but me and that was at least 100,000 miles ago when I replaced front hubs, rotors and...

www.ramforum.com

This is the problem. Thank you so much!