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abs engaging prematurely

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  • #442917
    thepopethepope
    Participant

      so this is on my 1998 gmc sierria k1500 4×4. Ive had this problem for awhile. It seams to happion when I’m comming to a stop (under 5mph) I changed both frount abs sencers (the only 2) The replacement sencers where acdelco (gm oem) I beleave from what I have herd the rear uses just one that the speedometer uses. any way it still happions. there is no abs light on. it happions alot like 1 in 5 times I push the peddel.

      I have removed the fuse for safty. especally since I almost ran into the back of some one. I mean its litterly fighting me to stop. Just to be clear I am on dry pavment and making slow stops.

      Whith the fuse removed every time I start the truck no abs light is on untill I make a few stops than it comes on.

      I have no way for checking for abs codes, but I was kinda thinking no light=no codes.

      I was hoping to fix it my self. but if I had to. I was thinking about taking it to the dealership. or a local shop witch I trust more, but I did not know if the local shop would have the equipment to fix it.

      but ya winter is comming up and I kinda need that. and sorry about my spelling I cant get spell check to work….

    Viewing 13 replies - 1 through 13 (of 13 total)
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    • #442918
      johnzcarzjohnzcarz
      Participant

        Since the ABS light is coming on after a few stops, I strongly recommend you take it to a shop and read out the codes – that should tell you exactly what’s wrong (or at least point you in the right direction). It’s going to be a lot cheaper in the long run even if you have to pay the shop to read the code vs. throwing money at it by guessing at what parts to replace.

        I wouldn’t worry about them having the right equipment – if they have the equipment to work on modern cars they should be able to pull codes out of any module. Let us know what the code is and maybe we can help out.

        #442919
        SpawnedXSpawnedX
        Participant

          The code is coming on because you have the fuse pulled. At this point you really need to get the system checked out, even if only for a diagnosis. I don’t even mess with ABS since I don’t have the equipment. Since I currently am doing mobile repairs, I have turned down 4 or 5 ABS jobs because it is not worth messing around with blindly, due to the nature of importance the system holds.

          #442920
          thepopethepope
          Participant

            NO THE ABS LIGHT DOES NOT COME ON!!! untill I removed the fuse for my safty. I could drive all over with the fuse in and the abs would freek out every few stops and no light would come on.

            so does no light = no codes.

            #442921
            dreamer2355dreamer2355
            Participant

              Having a scan tool to activate the ABS would be very helpful here.

              I would take it to a qualified technician to have it diagnosed then waste money throwing parts at it.

              Good luck.

              #442922
              johnzcarzjohnzcarz
              Participant

                +1 on dreamer.

                With a scantool you can ‘see’ what each speed sensor is reporting back to the abs unit. I know you said you replaced some of them, but it may be the wiring, the reluctor ring, etc. You need to know what the module is seeing.

                #442923
                EricTheCarGuy 1EricTheCarGuy
                Keymaster

                  Yea the system is set up with a self diagnostic to help you find the problem so you don’t have to blindly replace parts, my recomendation is to seek out someone with a scan tool capable of reading the ABS codes, reinstall the fuse and get the ABS light to come on then pull the code to see what it says, that way you will KNOW where to look instead of just guessing. There really are no short cuts here sorry.

                  #442924
                  danelidaneli
                  Participant

                    hey pope: I had a similar problem on my 96 honda. turns out I had chipped one of the teeth on the “tone ring” that the wheel sensor reads to determine wheel speed. Since one the wheels had less teeth for the sensor to pick up, the computer figured one of the wheels was turning more slowly than the others and it would activate the abs function. So I suggest you check the tone rings on all the wheels and make sure they aren’t damaged.

                    #442925
                    jacobnbr1jacobnbr1
                    Participant

                      You don’t always get a code when this happens!
                      Why? Because the module thinks the tire is actually slipping and the module is acting based on the software program is written. Meaning the system thinks the tire has encountered a skid on ice,gravel,mud etc.
                      Nonetheless the module thinks there is a valid cause but not an error.

                      You need a graphing scanner to watch for the signal fall out.

                      Does this vehicle have four wheel abs? and if so check and tell me if there is only two front sensors?

                      These things are a royal pain in the arse but I would check the integrated tone rings, make sure the sensors are seating all the way down in the hub and there is no debris collected on the tip of the sensors.

                      I always use a DSO to find these problems because you find it easily with that type of tool but a GM Tech2 will work if you have one handy.

                      If you suspect a tone ring you can buy a MOOG hub bearing that will come with a new sensor as well but don’t buy those cheap bearings unless you want to do it again.

                      #442926
                      Shaun_300Shaun_300
                      Participant

                        Did you clean the rust down to bare steel where the sensor sits on the hub? 9 times out of 10 it’s actually the rust that builds up under the sensor that causes the problems. It affects the air gap between the sensor and the reluctor which gives false wheel speed sensor readings. A bit more rust on the opposite side will give a different speed than the other side, the ABS module things the one wheel is slipping and engages the ABS. There’s actually a recall on the 99-02 GM trucks for this concern.

                        #442929
                        Trcustoms719Trcustoms719
                        Participant

                          Great job and thanks for the update!V-)

                          #442927
                          thepopethepope
                          Participant

                            I fixed this a long time ago thought I would give a update. one of my hub assemblies had a lot of play in it. I replaced the hub. works great now.

                            Thank you every one for your help.

                            #442928
                            dreamer2355dreamer2355
                            Participant

                              Thanks for posting the fix and using the ETCG forums!

                              #442930
                              EricTheCarGuy 1EricTheCarGuy
                              Keymaster

                                Yea thanks for coming back and posting the fix it will go on to help others using the search function. Thanks for using the ETCG forum.

                              Viewing 13 replies - 1 through 13 (of 13 total)
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