2nd Gen Non-Engine/Transmission soft brake pedal

[SFPADGETT]

95 , 2500 4x4, club cab, auto with 278,000 miles. ABS light and parking light are on and now the brake pedal will gently fall to the floor. The truck will stop ok, but the pedal is going almost to the floor. Rear sensor replaced (several times), brake module replaced, and master cylinder just replaced, but still the soft pedal. Replaced the short wiring harness wire from the rear diff to first junction and found shorted wire. Brake code still flashes "3", but have not been able to find source of the "bad wire" to dump valve as noted in the trouble codes. I can live with the lights on, but the soft pedal worries me.

 

[scotmartin]

You need a new master cylinder, immediatly!





Scot

 

[bmoeller]

You may still have air in the system. There is a certain order you have to go through, to get it bled out. I think the cheap Haynes manuals have it listed. I hope you bench bled the master cylinder before the install.



You could still have a bad master cylinder, even if it is new/rebuilt. My Ford needs a new one. Fluid can go back and forth between the front and rear parts of the reservior without leaking externally.

 

[SFPADGETT]

I will replace the master cylinder, again, this morning and re-flush the brake system.

 

[SFPADGETT]

Yes, we did use the Haynes manual and the Dodge service manual for the proper installation methods. We power flushed the the entire system according to the directions listed in the Dodge manual. Master cyl was bled prior to install, along with the RWAL and Combination valve. I will let everyone know the results of the new cylinder later this morning. Thank you for the help. Any additonal ideas are welcome also.

 

[John - K5AWO]

Be sure that you don't have any rubber parts on the wheel cylinders that are getting spongy (old age).



Also, be sure that you have flushed the entire system to all four corners of all the old fluid. Brake fluid must be flushed every 2 years by manufacturer's specs to get rid of water contamination.



Contaminated fluid feels spongy. The pedal going to the floor sounds like air in the system somewhere, and/or the replacement master cylinder isn't any good. ( I just love after market parts warrantied for life - I get to change, and change the, and..... change them for the rest of my life )

 

[SFPADGETT]

Friday afternoon update: New master cyl. installed,(pre-bled before install), much better feel, however, not as good as before, have bled almost a full gallon of fluid (DOT 3 ) thru system. No more bubbles, and clear fluid thru all fitings. NAPA is loving me! All rubber parts seem to be in good shape. I will run this weekend and check again in the morning. I will post updates when cure is found. I have always changed (compete flush) every spring and fall since the truck was new. We do our entire fleet this way since the trucks are off road alot on construction sites, then have to deal with stop / go traffic of ATLANTA. Brake fluisd is cheap compared to hitting a car in the rear with one of our trucks.

 

[John - K5AWO]

Had a thought - Are the rear brakes set up snug?



With drums, if they are backed off a few notches that pedal will never get "hard" at the top.

 

[SFPADGETT]

Update: Monday morning and brakes are alittle better after bleeding them two more times over the weekend. I'm wondering if I have had three bad master cylinders from NAPA? The rear brakes are adjusted where the first "click" from the parking brakes will apply pressure to the wheels and stop them when spinning by hand. It will take all of the parking brake to hold them when in "drive", 350 hp at wheels does this. It takes about half of the pedal for the brakes to start working, then works fine. I will continue to check and try things till corrected.



Thank you for the ideas and help.

 

[SFPADGETT]

Problem finally found and corrected!. BOTH front hubs on the 4x4 are worn again, there was just enough play / wobble to keep the brake pads pushed out and give the soft pedal feel. With new hubs installed yesterday afternoon, the brakes are like new, with a good firm pedal and good controlled stops. Thanks everyone for their ideas and help.

 

[fortunate1]

Did that stop the ABS & BRAKE lights? I'm going thru the same sort of thing now. Bleeding the whole system didn't stop it. But the grinding sound from the front left rotor got my attention. All pads very worn; inboard pad gone, and it had scraped some of the rotor. With wear and an earlier machining, there wasn't enough left to machine the rotors again. So new rotors, new pads. Braking is very good again, and the lights don't come on very often. But if I sit at a light for more than 30 secs, they'll come on. As soon as I push down on the accelerator to drive off, the lights go out. Vacuum leak? Where is the most likely spot to have one? It seems the pump pulls enough vacuum, but it leaks off during an extended stop with the engine at idle. Any ideas?

 

[SFPADGETT]

The abs light and parking light are still "on". I have a new wiring harness ordered that goes from the "dump valve" to the rear of the truck, as we have tested the wire and found that one of the wires is shorted to the frame. We used some "temporary" wires laid out on the ground to find solution.

 

[SFPADGETT]

Sorry about the "short post above" Your problem does sound like a vacum leak, the most common is a pluged vacum hose / fitting . Usually found on the front side drivers side of the motor, low on the block, near the power steering pump. There was a "recall" on this earlier on and a search for "vacum leak" should find it. It had some good pictures and other possible leak areas for both 2wd and 4x4's. Each has different vacum hose's and special problem areas.