Announcement

Collapse
No announcement yet.

So I got my ABS working and now the ABS computer hisses? Any idears?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    So I got my ABS working and now the ABS computer hisses? Any idears?

    Hey guys,
    Ever since i've had my convertible the ABS hasn't worked. I kinda like locking up the tires but I can't help but remember totally my old e30 in the pouring rain and thinking if I had ABS or the ability to pulse the brakes while watching the most retarded ish ever going down right infront of me I might still have it. Wait that car was a hoopty and my vert is nice....

    Anyhow it's not a race car and I decided I wanted ABS. So I replaced the missing bulb in the cluster, it needed both front sensors, threw those in and ABS works!

    Anyhow now almost all the time and especially noticable right after I switch off the car so the motors off and I can hear better, for about 10-15 seconds after there's an electrical hiss. Pressing the brakes makes it go away. I'm not 100% sure is the ABS computer but getting it working is all I changed. Since it goes off when I press the brakes I figure it could be something to do with the brake light curcuit, but really I have no idea.

    Anyhow if anybody has experienced this before or can give me an idea of what to check to make it go away I'd appreciate it. I hear it sometimes when the motor is quiet and it interferes with my high fidelity tunes pumping through my sick STEREO speakers.

    Now that I think about it I should disconnect the brake light switch and see if it still goes away when I press the brakes. That would answer whether it's something with the lights or something with ABS. Hell I have no idea how the ABS even works....I don't think the computer should know if the pedal is pressed necessarily right?

    just if 2-3 of the wheels are spinning and 1-2 are decellerating faster than the others and about to lock up it gives the pulse.

    Blah sorry for useless babble at end, tomorrow I'll check on the brake light switch thing but if anybody has any bright ideas I'd appreciate it.

    Thanks
    -Sam

    #2
    disconnecting brake light switch had no effect. wtf.

    Comment


      #3
      pinpoint the noise so we can help you better.
      this is obviously an electrical sound, normally from a relay.

      Comment


        #4
        It's the brake booster leaking vacuum.

        Comment


          #5
          Originally posted by matt View Post
          It's the brake booster leaking vacuum.
          Yea, quickly get out and yank the hose from the booster. You should hear it then.

          Check valve not working? or leaking?
          89 325is track project / 05 x5 / 99 M3
          E30 stuff for sale | Parts I'm looking for

          Comment


            #6
            Thanks for the ideas. I'll give that a whirl but it really sounds eletrical to me. I'll unplug the abs computer while its happening and see if it cuts out. It's a varied whizz/electrical hiss that changes as I press the brakes more or less. If unplugging the abs computer makes it go away I'll swap it out for another one and hope it goes away.

            Comment


              #7
              Originally posted by Mossman View Post
              Thanks for the ideas. I'll give that a whirl but it really sounds eletrical to me. I'll unplug the abs computer while its happening and see if it cuts out. It's a varied whizz/electrical hiss that changes as I press the brakes more or less. If unplugging the abs computer makes it go away I'll swap it out for another one and hope it goes away.
              ABS sensor?

              Unplug the sensor and see if it goes away.
              89 325is track project / 05 x5 / 99 M3
              E30 stuff for sale | Parts I'm looking for

              Comment


                #8
                It's the brake booster.

                Comment


                  #9
                  from the description he has given, it doesnt sound like vacuum leak.
                  once the engine is shut off, vacuum is completely released almost immediately. he states theres several seconds you can still hear it. though, i cant guess what kind of circuit that could be.
                  seriously, pinpoint the noise.

                  Comment


                    #10
                    Originally posted by xLibelle View Post
                    from the description he has given, it doesnt sound like vacuum leak.
                    once the engine is shut off, vacuum is completely released almost immediately. he states theres several seconds you can still hear it. though, i cant guess what kind of circuit that could be.
                    seriously, pinpoint the noise.
                    Vacuum is released from the intake manifold very quickly, but the check valve lets the booster hold vacuum until air finishes leaking in.

                    This is why A) it makes noise for a few seconds after he turns off the car when he doesn't hit the brakes and B) the noise stops right away if he does hit the brakes and C) it makes noise when he hits the brakes when the car is running and D) it changes as he modulates the brake pedal.

                    Trust me, it's a failing booster. Pretty soon the brake pedal will be a lot harder to work.

                    Comment


                      #11
                      Matt wins!

                      I've never seen/heard/dealt with a bad brake booster ever. That's why I never bothered taking one off of any of the e30's I've parted over the years. Go me.

                      Comment


                        #12
                        Need one? I have one. Worked fine, pulled to do M50 swap.

                        Comment


                          #13
                          well shit, my "just for agument sake" loses again

                          Comment

                          Working...
                          X