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    Front driver brake chatters as if in ABS mode?

    I have an 88 325ix with about 162xxx miles. I changed the front/rear rotors, pads and sensors just about 1000 miles ago and flushed/bled the entire brake system = all systems go!

    However, last week, something peculiar started happening. When I go to brake (no mmatter what the car speed is), as the car is coming to a halt, I can sense the front driver side brakes "chatter" as if the ABS is coming on (but it is not) just at the very last second or two just as the car comes to a full stop. No vibrations in the brake pedal or the steering wheel, just a slight sound of the chatter/grind. The Brake Lining light has since started to flicker on and off for no reason - even today. ABS light came on last Thursday for about 1 min and then went off and has not come on since.

    So this weekend, pulled the wheel off, inspected all the brake parts and nothing out of the ordinary: rotors are clean and no gouges or signs of hardening or cracking; pads are clean; calipers are not hanging up; brake sensor is in place; rotor hold-down screw as just barely loose so I tighted it; all caliper and caliper bracket bolts are present and snug. Drove car this morning, and same issue. Again, there is no loss of braking or pulling to one side or vibrations or anything as such - only the chatter at the last sec or to as the car comes to a stop.

    Any thoughts, ideas or advice would be greatly appreciated.

    Thank you.

    #2
    Yes, did you drive the car to "SEAT" the pads properly? also you may be having a partially seizing caliper. Not enough to create a pull but enough that under very low speed the pads are hanging up. what brand of front rotors are you using is the other question. if you cheap out and buy some off brand you may have 2nd or 3rd line run which depending can often warp over very short period of time. the same goes for the pads.

    the lining light can simply mean that either the sensor isn't sitting properly in the pad or you might have a small break in the wire or it wasn't plugged in properly.

    double check everything.

    Heck! swap the rotors around and see if the problem goes to right side.

    Hope this helps.
    sigpic

    Comment


      #3
      OEM Rotors and pads are from Pelican Parts, and yes, the rotors/pads were seated/broken in correctly. Coloring is consistent on all 4 rotors.

      One thing I forgot to add: This started to occur after I had to come to a hard stop early last week at an interesection due to a callous driver!

      Someone mentioned possible broken pad retaining clip, which is causing pad/s to chatter towards end of braking while coming to a stop. Will check again...

      Comment


        #4
        Checked the rotors and front driver hub assembly, but still no go - if anything, the "ABS-like" chatter appears to be a bit more pronounced just as the car is coming to a stop and I can feel the ABS pulsation in the brake pedal. The Brake Lining light is on, but the ABS light has not come on again nor does it flicker when the brakes chatter.

        Thoughts?

        Comment


          #5
          First you need to find out whether this is from the ABS or the brakes. The way to do that is to disconnect the ABS module, drive the car, and see if the problem is still present.
          The car makes it possible, but the driver makes it happen.
          Jim Levie, Huntsville, AL

          Comment


            #6
            Thanks - I will use this procedure as outlined by you:

            "Troubleshooting the ABS system isn't very difficult. It is a stand alone
            system that only gets input data from the brake light switch, wheel sensors and
            system power. The parts of the system are the ABS module located next to the
            steering column, the ABS relay mounted above the ABS module, the ABS unit in
            the left front of the engine bay, and a wheel speed sensor at each wheel.

            If the ABS light comes on with ignition, but doesn't go out when the engine
            starts, a wiring problem, bad module, or bad ABS relay are the likely
            candidates. A failed or weak alternator will also cause this because the
            system voltage won't rise enough. There is a fusible link inside the ABS relay
            that can be blown. The relay can be repaired, or better yet replaced.

            If the ABS light comes on when you turn on the ignition, goes out when the
            engine starts, and then comes back on before the car is moving the cause could
            be a bad module, a bad ABS unit, or a wiring fault.

            If the light goes out after engine start and only comes on when the car is
            moving, there's a problem with one (or more) of the sensors. The simple test
            to find out which sensor(s) is the cause is to disconnect all but one of the
            sensors and drive the car. If the light comes on, that sensor is sending a
            speed signal to the ABS and is good. Repeat with each other sensor to find the
            one(s) that don't cause the light to come on. Since the ABS module has no
            speed input besides the wheel sensors, if only a bad sensor is connected the
            module can't tell the car is moving and thus doesn't fault on missing speed
            signals from the other wheels. Once a bad speed sensor is found, if a new
            sensor still doesn't work, there could be a wriing fault in that circuit or a
            bad input channel in the ABS unit. "

            Will post results/outcome.

            Comment


              #7
              From what you have described, the ABS light only came on one time and isn't on now. Let's prove that this is an ABS problem by what I described above first.
              The car makes it possible, but the driver makes it happen.
              Jim Levie, Huntsville, AL

              Comment


                #8
                You are correct, the ABS light only came on once and after parking the car for a few hours and restarting, the ABS light went out and has not come on again once the engine has started.

                Will disconnect the ABS module and post what I experience then.
                Thank you.

                Comment


                  #9
                  Ok, disconnected the ABS module under the dash.
                  Started car - ABS light is on.
                  Drove car = no chatter or pulsations.
                  Connected the ABS module again.
                  Drove car = chatter and pulsation came back.
                  Thus, am I correct in assuming the ABS module is bad? I parked the car and disconnected the ABS module for the time being as I figure nothing will get harmed by running the car without it for the time being.
                  Will any E30 ABS replacement module work or do I need to get an "ix" specific module? ABS module model #0 265 105 011

                  Thanks

                  P.S. not sure if it matters or not, but I had to jump start my car 2x about 2 months ago when I left my headlights on for the entire day (no chime reminder to turn off the lights) - lesson learned! Also, when I press the brake pedal (or turn on the turn signal or wiper), I can tell the OBC dims ever so slightly for a split sec...
                  Last edited by tirefryer; 05-31-2012, 05:45 AM. Reason: more info...

                  Comment


                    #10
                    That says that the problem is with the ABS. The first thing I'd try would be a different module. I think you need an IX specific part.
                    The car makes it possible, but the driver makes it happen.
                    Jim Levie, Huntsville, AL

                    Comment


                      #11
                      I have the same problem in a us 325 1986, the chatter is a pain in the butt.


                      and only happened with the ABS on, without the abs relay the chatter gone away.

                      Changed: brake discs, brake pads, flushed... still no go

                      Comment


                        #12
                        Originally posted by jlevie View Post
                        That says that the problem is with the ABS. The first thing I'd try would be a different module. I think you need an IX specific part.
                        Alrighty then...
                        Finally was able to source a working 88 ix ABS module.
                        Plugged it in, started the car = ABS light off after initial check
                        Just getting out of my driveway, pressed the brakes = "ABS-type" chatter from the driver front returns (ABS light did NOT come on)
                        Turned off the car, unplugged replacement ABS module = drove car = no chatter
                        turned car off, plugged in the replacement ABS module again to verify = chatter returns, despite stopping from 10mph or 40mph on flat, dry even road.

                        In light of this, what would my next steps be - inspect the ABS speed sensor on the front driver hub?

                        Thanks.

                        Comment


                          #13
                          I think I'd replace the right front sensor.
                          The car makes it possible, but the driver makes it happen.
                          Jim Levie, Huntsville, AL

                          Comment


                            #14
                            Ok, update:
                            Got it figured out and car runs great...finally! :D
                            I tested all the speed sensors while still in the car, and they all tested fine... Same resistance in all. None of this is making any sense. So I sourced a set (4) of know good speed sensors and tested then when I got them... Tey all ested the same resistance as the ones in the car... WTH?!?!
                            So last week I took out all 4 speed sensors from the car (was putting on snow wheels so figured might as well) and tested them out of the car and result = 2 bad speed sensors (pass side front and driver side rear)! Both had a short in the wires since when they were in the shape (when installed in the car), good circuit. As soon as I moved the wires ever so slightly, short in the wiring and multimeter was all over the place. This lead me to believe that at a standstill, signal to module was fine, btu as soon as the car started to move, the wires in these 2 sensors would short and lead to the ABS malfunction.
                            Replaced all 4 speed sensors for the piece of mind, installed my orig ABS module, went for a test drive and success! :)

                            Moral: when testing wires or wiring systems, move and manipulate them since they might be making contact when car is still, but as soon as it moves, the wire could potentially short out or exhibit weird symptoms.

                            Hope this helps. Thanks to everyone who assisted me in solving this issue.

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