abs brakes
Thread Starter
Joined: Feb 2006
Posts: 2
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abs brakes
I have an issue with the brakes on a 98 ram 1500 4x4. It seem the abs engages every time I hit the brakes. I have no pedal. The abs light comes on everytime I push the brake pedal. In park I have no indicator lights.
Originally I had a leaking line in the rear and the shop told me that the loss in pressure caused the lack of pedal and the abs and brake light to come on, so I fixed it along with new pads and shoes. The abs and brake light were still on constantly. I changed the battery(weak battery) and unplugged the abs control box thinking it may need a reset. Presto the abs and brake lights were out when I restarted the truck, but still no pedal. I rebleed the system and noticed air in the the fluid. After runing nearly a quart of fluid through it was still milky, and thought probably the mastercylinder was allowing air into the system. I replaced it. I see no air now. still no pedal and abs light still comes on. After reading the forums here and researching other online sources It seems people have issues with the toner ring and rear speed sensor however the speedo works properly so I havent replaced it, could it still be defective?
At this point I am stuck I have three items left in the system, the control module, proportioning valve and the abs motor assembly(terminology correct?). Anyone coach me on diagnosis? Have I missed something? Can I mechanically bypass the ABS control unit and motor? Any input is appreciated.
mpyrol
Originally I had a leaking line in the rear and the shop told me that the loss in pressure caused the lack of pedal and the abs and brake light to come on, so I fixed it along with new pads and shoes. The abs and brake light were still on constantly. I changed the battery(weak battery) and unplugged the abs control box thinking it may need a reset. Presto the abs and brake lights were out when I restarted the truck, but still no pedal. I rebleed the system and noticed air in the the fluid. After runing nearly a quart of fluid through it was still milky, and thought probably the mastercylinder was allowing air into the system. I replaced it. I see no air now. still no pedal and abs light still comes on. After reading the forums here and researching other online sources It seems people have issues with the toner ring and rear speed sensor however the speedo works properly so I havent replaced it, could it still be defective?
At this point I am stuck I have three items left in the system, the control module, proportioning valve and the abs motor assembly(terminology correct?). Anyone coach me on diagnosis? Have I missed something? Can I mechanically bypass the ABS control unit and motor? Any input is appreciated.
mpyrol
Professional
Joined: Jan 2006
Posts: 191
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From: Ottawa, Ont.
RE: abs brakes
Proportioning valve or the ABS motor assembly (unit?) would be my guess. You could maybe de-ABS the truck by bypassing this ABS unit (rerouting the lines) so you could atleast get the pedal back.
Thread Starter
Joined: Feb 2006
Posts: 2
Likes: 0
RE: abs brakes
Problem continues;
I used an adapters (Metric lines) and line to bypass the ABS hydraulic control unit. Re routing lines are impossible as connection is different at proportioning block and output of ABS block. Still I had no pedal even after bleeding. I kept getting air out of the line, I would get some pedal then no pedal. As it turns out once the pedal passes a certain point (depression of the master cylinder) it allows air into the system.
Solution;
The solution was to bleed in very small amounts making sure the pedal motion towards the floor was limited. With the truck running it was almost impossible not to push the pedal to the floor so it was bled with no boost.
Conclusion;
Finally, the brakes work and ABS is no longer a part of the system. I am aware that the pedal has adjustment between the master cylinder and the booster but I never ran into an instance where adjustment was necessary. I notice no out of ordinary function currently so I do not plan to open another can of worms. I have concluded that this new master cylinder does introduce air into the brake system at long pedal/brake travel. No mention is made anywhere that I can find. I suppose most shops use auto bleeders. If I could have found this tidbit of information it would have saved me hundreds of dollars. I hope it helps someone else.
Brian
I used an adapters (Metric lines) and line to bypass the ABS hydraulic control unit. Re routing lines are impossible as connection is different at proportioning block and output of ABS block. Still I had no pedal even after bleeding. I kept getting air out of the line, I would get some pedal then no pedal. As it turns out once the pedal passes a certain point (depression of the master cylinder) it allows air into the system.
Solution;
The solution was to bleed in very small amounts making sure the pedal motion towards the floor was limited. With the truck running it was almost impossible not to push the pedal to the floor so it was bled with no boost.
Conclusion;
Finally, the brakes work and ABS is no longer a part of the system. I am aware that the pedal has adjustment between the master cylinder and the booster but I never ran into an instance where adjustment was necessary. I notice no out of ordinary function currently so I do not plan to open another can of worms. I have concluded that this new master cylinder does introduce air into the brake system at long pedal/brake travel. No mention is made anywhere that I can find. I suppose most shops use auto bleeders. If I could have found this tidbit of information it would have saved me hundreds of dollars. I hope it helps someone else.
Brian