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1994 Plymouth Grand Voyager Question: ABS light comes on and back pressure on pedal and noise when brakes applied

 

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CptTrevor, 3.3L V6, Lehigh Acres, FL, November 25, 2010, 12:25
 Rookie

The ABS light on my dash comes on every so often when I shut the van off and restart it might come on again or sometimes not. When I apply the brakes it makes a noise and the pedal push back on me like a back pressure. I have brakes but I don't like the noise and the pushing back on the pedal. The master cylinder does not creep forward under pressure it holds. I check the vacuum for leaks and any damage to the valve I can't find any damage to lines or cracks. Could my ABS pump be making that noise when I apply the brakes? can I bleed the ABS pump or how do I check that to determine if it is bad .I have a my own scanners would this help me to tell if the problem is in the pump or wheel sensors? Please help I change the wheel cylinders front caliper, brake pads and still the problem with the noise and in my opinion some abnormal pressure on the pedal. Can you help me with a solution. I am a mechanic but I never encountered this problem before this is my own van. CptTrevor

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  • Answer #1

    November 25, 2010, 16:11
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     Master

    The ABS pump is absolutely causing your noise and kick back in the pedal. But it's not because it's faulty. It's because there is a sensor issue. The wheel sensors that measure wheel speed are what tells the module to turn the pump motor on and pump your brakes. This is when one or more of the sensors shows "0" mph or even a negative number when the sensor fails. Check for failed sensors with a diagnostic tool. Or, just physically look at the wiring connectors at each sensor - make sure nothing is displaced or damaged. Make sure the sensor face is clean of debris and corrosion. Make sure the indicator rings that the sensor reads are not dislodged or damaged. Clearance between the sensors and indcator rings should be the same all the way around too.

    Hope this helps.

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    CptTrevor, November 25, 2010, 16:19
     Rookie

    thank you very much I would put my scanner and see what the code say and then I would check all the sensors. I now know what to look for and how to approach the problem. I would get back to you in a couple of days when I have time to check it out and fix it and let you know what is the verdict. CptTrevor

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    DaveJHM, November 25, 2010, 16:27
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     Master

    Keep in mind there may be no code present. Especially on a 1994. If you are able to monitor wheel speed sensors with your scan tool - that will help very much.

    Definitely keep us up to date! Happy Thanksgiving.

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    CptTrevor, November 26, 2010, 08:19
     Rookie

    I have an OBD 1 scan tool for this vehicle would this help I just bought it from Amazon never use it but maybe this a good time to try it out. I am accustomed to using the OBD11 but this one I have to read instructions. Is there something in the sensors that is suppose to come out when the brakes are engage to help with the braking of the vehicle?

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    DaveJHM, November 26, 2010, 19:06
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     Master

    Your scan tool will not monitor the ABS sensors.

    No, the sensors are electrical only and send signals to the module.

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    CptTrevor, November 27, 2010, 04:45
     Rookie

    I was told by a mechanic that there is something in the middle that engages the brakes now I know there is nothing. I am having trouble removing the screw that hold the sensor unto the spindle housing. Do you have any suggestions I am soaking it in WD40 I do not want to break that screw off.Where are these sensors plug into the vehicle in the engine compartment. I saw them on Amazon for 50 dollars and else where for as much as 200 dollars each. I want to remove them and clean them CptTrevor

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    DaveJHM, November 27, 2010, 08:12
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     Master

    PB blast is a good penetrating oil. WD-40 is a start. You are right to soak it before you break it, and even then, depending on corrosion, it can break.

    I can't tell you right up front where they plug in other than at the sensor harnesses themselves.

    Did you determine which sensor was at fault? It would be advisable not to remove sensors unless you find a failed one.

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    CptTrevor, November 27, 2010, 19:50
     Rookie

    I finally got the screw out with lot of words and plenty of transmission fluid mix with acetone this is a good rust buster. Anyway when I got to screw out and tried to remove the sensor it fell apart in my hand and would not come out of the hole in the housing of the hub. I had to actually dig it out. I ordered a new one from Amazon. I have not attempted to clean the drivers side because I am afraid it probably is in the same condition. I do not have a diagnostic tool to check them so I was just checking for corrosion and bad connections or broken wires. I could not move the sensor and by the time I got the screw out the sensor would not come out instead it fell apart in my hand. Can I drive the Van until I get the new sensor or should I deadline it until I replaced the sensor I am not too familiar with these sensors but by the time I am done I would know how they operate for the future. Thank you for your help CPTTREVOR

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    DaveJHM, November 27, 2010, 20:49
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     Master

    Without the sensor, it will be in the same condition - no working ABS. In fact, the ABS system probably won't power up at all, meaning your kicking back issue will not happen either.

    Having a sensor fall apart like that is normal, especially in high corrosion areas.

    I am concerned, however, that your trial-and-error method of diagnosis will end up with big headaches and expense. Continued good luck.

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    CptTrevor, November 28, 2010, 06:23
     Rookie

    can I put the wheel back on and drive the van until I received the new sensor? Or is it dangerous to drive this way? would my braking be affected in any way by the senor removal?please advise. CptTrevor

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    DaveJHM, November 28, 2010, 10:27
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     Master

    Theoretically you can put your wheel back on you could drive - and your ABS will just not work.

    However, my official position is that it is dangerous to drive a malfunctioning vehicle and I would never suggest that you can drive your vehicle without it being equipped as designed. You should never drive defeating the safety equipment of the vehicle.

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    CptTrevor, November 28, 2010, 15:57
     Rookie

    can I put the wheel back on and drive the van until I received the new sensor? Or is it dangerous to drive this way? would my braking be affected in any way by the senor removal?please advise. CptTrevor

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    CptTrevor, November 28, 2010, 16:00
     Rookie

    You are absolutely correct. I have a van I can drive until the part arrives. Thank you for your professionalism and honesty I would be in touch and keep you inform as to what happen to the other side and when I replace the new one this is a learning experience for me CptTrevor

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