My buddy has a 1996 Dodge Ram 2500 with auto tranny and he had a spongy brake pedal and took his truck to his local shop to have it checked out. They replaced everything from what I can tell except the front calipers. Rear shoes and wheel cylinders front disk pads and the master cylinder and booster. After picking up the truck the brake system warning light is on and the abs light is on and he has a spongy brake and when he presses it harder it becomes very hard and goes toward the floor. He took it back and they rebled the system but the problem still is there. He contacted the Dodge dealer and they can't get it into the shop for 3 weeks. I changed my wheel cylinders switching to the NAPA cylinders oversize and new rear shoes, also replaced the master cylinder and booster and had to make a few stops with no further problems. They have suggested he may need a new abs module to the tune of $1400.00. Any ideas or suggestions would be welcomed. Also an alternate source for the abs module if it is needed would be nice.

 

W.o. being here I will take a hipshot, old front hoses,create worn/spongy feel.
silicone brake fluid never gives the same kind of feel as the older dot 3 stuff.Any where there is a rubber hose I would suspect it .(again if its soft on the inside it expands as the pedal is pushed so the force never gets to the brake cyl/caliper.
last, maybe 1st, bleed the sys.

 

Sometimes if the calipers are forced back with a clamp to replace the pads the abs unit will be damaged. The fluid in the calipers is by far the dirtiest in the system, forcing it back into the abs and master is a bad idea, the bleed screw should be open.
It would really suck if the guys that did the brake work had to learn this at your friend's expense as I doubt the unit was damaged before he had the work done.
I find it very fishy that they had to replace the booster as the '96 has vacuum assist which very rarely has any problems.
Somehow I feel that your friend got taken and way more work was done than necessary.

 

That could be what happened as I don't really know the shops expertise. I also have a 1996 and I did have to replace my vacuum booster as it went out. The symptom he is having of a soft spongy pedal and then losing pedal and having a hard pedal with little response from the brakes was the same as I had before changine my booster. His has been changed and I told him that they could test it and how with a vacuum pump and also check to see if he is getting good vacuum to the booster. It's pretty sad as I had already had him get new shoes and the larger rear wheel cylinders to give him better braking and that stuff sat at home as he didn't remember to take it in. My buddy is a MD and not always thinking correctly in the mornings as he works night shifts in the ER.

 

Well the saga goes on. The original shop that rebuilt the brake system says they can't do anything else and so the truck went to another shop and they replaced the vacuum booster again with a new item this time. At no cost for the booster but an additional labor cost. The truck now has brakes but only for one stop and then the hard pedal again. I am wondering if the vacuum pump is putting out the proper vacuum? Also I read in one of the threads about a valve or something under the drivers side battery tray which might be indicated. I will go back and reread threads and try to find that. Still have the lights on however and will check the rear wheel sensor. Our Dodge dealer says $140 for the sensor, does anyone have a part number? I haven't gotten my hands on the truck yet so will know more after I get to check things out. Kind of wanted to stay out of it as I didn't start it.

 

This is going to sound real stupid, but did anyone replace the HOSE going to the booster? That is one of the most overlooked items with the symptoms described.
Tom

 

Got the truck in my hands and checked vacuum from the pump to booster and found 26 inches of vacumm with all other lines disconnected. Then started testing the other vacuum lines and found a break in the vacuum hose that goes down behind the engine block I believe to the shift valve for the 4 wheel drive. Plugged that line and the system works fine. Also both break light and abs light went out and stayed out. We have put a manual engagement on the 4wd previously so don't use that hose as far as I know. After disconnecting this hose and checking the plug at the axle I no longer have vacuum at the axel so am assuming that is the only place it goes. Not a problem as we are not using that line at this time. Thanks for all the help it made it easy to check things out.

 

Good for you. It's sure disappointing that the repair shop couldn't figure that out. How could they replace a booster without checking its supply??

 

The sad part is there were 2 shops involved and they both indicated to my buddy that they checked the vacuum system and the 2nd one said they tested the system using a smoke test, I suppose injecting smoke into the vacuum system and looking for leaks but did not find the problem. All of this occurred out of sight of the owner. I bought $7.83 worth of 12 inch hoses different sizes and a universal tee and universal connector and already had a vacuum gauge pump tool and the owner watched me check the system. He even told me 2 or 3 times that they had already checked the system. I told him they may have said they did but I was going to do it again. I can only believe they only checked the line from the vacuum pump to the booster. It had 26 inches of vacuum at idle, but with the complete system connected and a tee in the system going to the vacuum gauge it dropped to 5 inches at idle and no brakes. The owner called the first shop that charged him $900.00 for the brake job and told the owner that I had found the problem and fixed it within 20 minutes. I don't know how that made him feel but at least I don't use him for a mechanic.