Technical Braintrust --> Anti Lock Dash Light ON! (13 years long issue)

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  • ADA///M
    White Chocolate
    • 20, 12, 2002
    • 7118

    #46
    My light doesnt come on until I start rolling....if it doesnt come on at all, the ABS acts crazy and the car will barely stop.

    I'm hoping its just needing new sensors all around.

    Comment

    • hardtailer
      Registered
      • 24, 7, 2004
      • 1820

      #47
      Unplug all 4 wheel speed sensors and make a mental note of how the ABS light behaves upon ignition on, start engine, running engine and pulling away up to a speed of at least 10 mph.

      Reconnect a single speed sensor. If the abs warning lights behaves exactly as you memorized, the sensor , connection and/or loom to the ABS ecu is defective.
      If the light comes on when pulling away, then that sensor is fine.

      Repeat with all 3 remaining wheel speed sensors but remember to check a SINGLE sensor at a time.

      Comment


      • hardtailer
        hardtailer commented
        Editing a comment
        Got this little gem off the SIG mailing list, originally posted by Don Fields
    • CamayroZ
      '88M3 since '88
      • 18, 11, 2021
      • 84

      #48
      Originally posted by hardtailer View Post
      Unplug all 4 wheel speed sensors and make a mental note of how the ABS light behaves upon ignition on, start engine, running engine and pulling away up to a speed of at least 10 mph.

      Reconnect a single speed sensor. If the abs warning lights behaves exactly as you memorized, the sensor , connection and/or loom to the ABS ecu is defective.
      If the light comes on when pulling away, then that sensor is fine.

      Repeat with all 3 remaining wheel speed sensors but remember to check a SINGLE sensor at a time.

      This is very good advice. And it is very easy to also measure each sensors resistance.

      Comment

      • ADA///M
        White Chocolate
        • 20, 12, 2002
        • 7118

        #49
        Originally posted by hardtailer View Post
        Unplug all 4 wheel speed sensors and make a mental note of how the ABS light behaves upon ignition on, start engine, running engine and pulling away up to a speed of at least 10 mph.

        Reconnect a single speed sensor. If the abs warning lights behaves exactly as you memorized, the sensor , connection and/or loom to the ABS ecu is defective.
        If the light comes on when pulling away, then that sensor is fine.

        Repeat with all 3 remaining wheel speed sensors but remember to check a SINGLE sensor at a time.
        Thank you!

        Comment

        • ADA///M
          White Chocolate
          • 20, 12, 2002
          • 7118

          #50
          Originally posted by CamayroZ View Post


          This is very good advice. And it is very easy to also measure each sensors resistance.
          Do you have to measure it while the car is rolling?

          Comment

          • hardtailer
            Registered
            • 24, 7, 2004
            • 1820

            #51
            Measuring resistance of a sensor can be done stationary. Search for the spec but generally speaking either 0 or very high (off the scale or out of range) resistance means bad sensor or bad (wiring) pig tail.

            Should you want to measure the signal by means of an oscilloscope or a Volt meter (set to AC!) you want the wheels turning.

            Comment

            • ADA///M
              White Chocolate
              • 20, 12, 2002
              • 7118

              #52
              Originally posted by hardtailer View Post
              Measuring resistance of a sensor can be done stationary. Search for the spec but generally speaking either 0 or very high (off the scale or out of range) resistance means bad sensor or bad (wiring) pig tail.

              Should you want to measure the signal by means of an oscilloscope or a Volt meter (set to AC!) you want the wheels turning.
              When i was half-ass checking them recently, I noticed almost all of my connectors on the harness side were falling apart, so i can't tell which way they should plug in. Does it matter (i.e. polarity)?

              Comment

              • CamayroZ
                '88M3 since '88
                • 18, 11, 2021
                • 84

                #53
                During my CSI work, I did not make any measurements myself, since I was able to troubleshoot my issue to the incorrect ABS tone wheel (ring).

                However, I did remove all my wheels, checked the sensors, checked the wiring, connectors, etc.

                **One of the experts should verify this: ** When I looked at the ABS speed sensors at close up, they looked like the old style "Magnetic pick up" sensors and not the newer "hall effect" type sensor. Therefore, they should just be a "coil" or "inductor" that is activated by the passing of the ferrous ABS tone wheel. Basically, a sine wave is generated as the ABS teeth goed by, and thus why you would need an oscilloscope to look at the actual signal which is only generated when that ABS wheel is spinning! :(

                Therefore, the resistance of the sensor will be low, since they are basically a "coil" or an "inductor", and polarity should NOT matter.

                Good luck to you!

                Comment

                • jimmy p.
                  3 x e30 m3s All with S14s
                  • 30, 12, 2002
                  • 3597

                  #54
                  Originally posted by CamayroZ View Post
                  During my CSI work, I did not make any measurements myself, since I was able to troubleshoot my issue to the incorrect ABS tone wheel (ring).

                  However, I did remove all my wheels, checked the sensors, checked the wiring, connectors, etc.

                  **One of the experts should verify this: ** When I looked at the ABS speed sensors at close up, they looked like the old style "Magnetic pick up" sensors and not the newer "hall effect" type sensor. Therefore, they should just be a "coil" or "inductor" that is activated by the passing of the ferrous ABS tone wheel. Basically, a sine wave is generated as the ABS teeth goed by, and thus why you would need an oscilloscope to look at the actual signal which is only generated when that ABS wheel is spinning! :(

                  Therefore, the resistance of the sensor will be low, since they are basically a "coil" or an "inductor", and polarity should NOT matter.

                  Good luck to you!
                  Correct, the old style are simply inductive. They are nothing like the newer modern sensors. The E30 ABS computer is simply looking for matching voltages.
                  jimmy p.
                  87 E30 M3 Prodrive British Touring Car
                  88 E30 M3 Zinnoberot - Street
                  88 E30 M3 Lachsilber - Race (#98 SCCA SPU)
                  92 E30 M Technic Cabrio - S14 POWERED!
                  98 318Ti M44, Base - Morea Green
                  04 Ford F350 - V10

                  Comment

                  • nrubenstein
                    Registered
                    • 20, 7, 2009
                    • 464

                    #55
                    Originally posted by jimmy p. View Post

                    Its been a while since I had the two versions side by side but the hub assembly itself "should" be identical, just the ABS ring should be different. I dont remember any noticeable to the eye differences other than the ABS rings. At least for over 20 years I have thought they were identical parts other than the ABS ring.

                    I have a piece of PVC pipe I use to install the cup, its the diameter of the recess, then I just tap it on.
                    No grease on the bearings, they are sealed.
                    I've compared Genuine BMW E30 M3 hubs to the E28 hubs. The "Genuine" hubs from both SKF and FAG carry E28 part numbers. The only difference was the somewhat halfassedly pressed on ABS ring.

                    I will note that the Genuine SKF hub didn't fit correctly. I ended up swapping it out for an E28 FAG unit.
                    2011 BMW M3 Alpinweiß
                    2006 GMC Sierra 2500HD
                    1990 325is Brilliantrot

                    1989 M3 Alpinweiß
                    Hers: 1996 Porsche 911 Turbo
                    Hers: 1989 325iX Zinnoberrot

                    Comment

                    • CamayroZ
                      '88M3 since '88
                      • 18, 11, 2021
                      • 84

                      #56
                      Since we can post pictures again
                      I am bumping this thread with pictures and part numbers for future folks chasing down ABS light issues. Mine was due to incorrect E28 hubs. Thanks again!!​

                      Click image for larger version  Name:	2.jpg Views:	0 Size:	224.2 KB ID:	1317065 Click image for larger version  Name:	4.jpg Views:	0 Size:	262.1 KB ID:	1317066
                      Click image for larger version  Name:	1.jpg Views:	0 Size:	254.8 KB ID:	1317064



                      Comment

                      • nrubenstein
                        Registered
                        • 20, 7, 2009
                        • 464

                        #57
                        Hopefully your SKF hubs don't have oversized hub centers like mine did.
                        2011 BMW M3 Alpinweiß
                        2006 GMC Sierra 2500HD
                        1990 325is Brilliantrot

                        1989 M3 Alpinweiß
                        Hers: 1996 Porsche 911 Turbo
                        Hers: 1989 325iX Zinnoberrot

                        Comment

                        • Ron ///Man
                          Registered
                          • 7, 2, 2005
                          • 2009

                          #58
                          I can't tell you how many E30 M3's I've seen with incorrect front hubs. People either just don't pay attention or don't care and just slam the 5 series bearing hubs on while ignoring the small details about swapping the ABS rings and picking the "correct" 5 series hub that has the right hub centers...
                          Ron ///Man

                          • '91 Gr-A Former CiBiEmme / Ravaglia - Sold
                          • '90 M3 Faux EVOII Alpineweiss 36K Orig Owner - The Queen
                          • '91 M3 Faux EVO III Brilliantrot Euro Driveline - The Rocket
                          • '91 M3 Faux Gr-A Club Racer DM - The Alter EGO
                          • '89 M3 M3T / ITR Club Racer
                          • '94 Spec E36 - Eh....
                          • '09 M3 - Tarmac Terrorist
                          • '04 330Xi Sport 6 Speed - Snowmobile
                          • '07 530 Xi - Highway Star
                          • http://www.imwcarparts.com/e30-m3-parts.htm


                          Comment

                          • nrubenstein
                            Registered
                            • 20, 7, 2009
                            • 464

                            #59
                            Originally posted by Ron ///Man View Post
                            I can't tell you how many E30 M3's I've seen with incorrect front hubs. People either just don't pay attention or don't care and just slam the 5 series bearing hubs on while ignoring the small details about swapping the ABS rings and picking the "correct" 5 series hub that has the right hub centers...
                            This was a Genuine BMW E30 M3 SKF picked up by me from the parts counter that had the wrong hub center. Just slightly oversized, so you could make it work, but it was ugly. After fighting with it for a while, I replaced with an E28 FAG unit (ABS ring swapped).
                            2011 BMW M3 Alpinweiß
                            2006 GMC Sierra 2500HD
                            1990 325is Brilliantrot

                            1989 M3 Alpinweiß
                            Hers: 1996 Porsche 911 Turbo
                            Hers: 1989 325iX Zinnoberrot

                            Comment

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