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Cycling ABS Solenoid Valves - Need help

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    #16
    I run HP+'s and have zero issue getting the ABS to actuate after rebuilding the calipers, and new SS lines... I think you have other issues Nando.

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      #17
      Hp+ are not HPS.
      Build thread

      Bimmerlabs

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        #18
        Originally posted by vpilarrt View Post
        Yes, ground pins 27 and 28 on the control module located under the dash on the driver's side. This turns on the pump motor and opens the solenoids.
        Does anyone have a diagram for the pin numbers. I've searched the internet and can't find anything.
        JOY IS AN E30...

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          #19
          Originally posted by nando View Post
          Hp+ are not HPS.
          ^This.


          When I bought my car, it came with HP+ and it felt great, but the brakes squealed like a sonuvabitch.

          When the time came to change, I wanted to keep as much stopping power as I could, but without a lot of squeal/dust. I went with new brembo blanks and HPS, and brake feel/stopping power is nowhere near where it was before.
          Originally posted by priapism
          My girl don't know shit, but she bakes a mean cupcake.
          Originally posted by shameson
          Usually it's best not to know how much money you have into your e30

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            #20
            HP+'s def make noise, but I have only ever run those on track cars so it didn't bother me on the street. Seems like Pagid's have the best compromise for street.

            I have a full electrical diagram of the ABS that shows the number of the pins and where they go from the control unit - BUT it doesn't show how the order of how the pins are numbered on the male or female end of the connector.
            JOY IS AN E30...

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              #21
              Wow, hadn't seen that this tread was brought back from the dead. My problem ended up being cruddy bargin-bin brake pads. I had no idea there was that much variation in performance of supposed "OE equivalent" brake pads. I put in a set of ATE OEM pads, and now its back to 100%. I guess you do get what you pay for.

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                #22
                So the ABS valves are open by default, meaning we should not have to cycle them at all when we bleed brakes as long as the car is off and we are using a pressure bleeder. Correct?
                Last edited by Wh33lhop; 03-27-2014, 05:49 PM.

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                  #23
                  I've never had to in 12 years.
                  Build thread

                  Bimmerlabs

                  Comment


                    #24
                    I could relay my really lengthy saga trying to get some pedal feel out of the brakes & air in the abs unit, but, really, ya'll would be asleep by the end of the story. Out of time and desperate for brakes before an event, with an extra set of ss-lines on hand, I bypassed the ABS unit. Last year I was determined to get it back, and opted to leave no brake-bleeding stone unturned.

                    Anyway - sitting here without pics and a bit from memory, what I did to get the abs unit to cycle was jumper 87 & 30 connections on the abs unit as shown in the OP's pics.

                    Obviously that means popping off both relays and wiring up some jumpers - easily enough done with some radio shack connectors of the right size & a short length of wire.

                    Apparently in shack-speak, these are either "Bullet" crimp connectors, or maybe "Snap" connectors, along the lines of:





                    I had a selection on hand from which I was able to use the right size, but I'd have to go dig 'em up to be more specific on which connectors I used - I think they had yellow plastic on the bases for a larger gauge wire than the links above.

                    Jumpering like this is all done up at the abs unit, no getting under the dash or accessing the ABS electronic control brain/module in the interior.

                    The OP's pic shows the topside of the plug that plugs into the abs unit with the plug cover removed, and the plug still plugged in. I left the cover on & simply unplugged it (I think the cable is clamped in place with a plastic bridge piece secured by a couple of screws, maybe torx), and used jumpers between the plug and the abs unit (again, pretty easily wired up w/ right-sized connectors sourced from radio shack).

                    I ran two jumpers out of one connector for power rather than make up a jumper for the two power connections of pins/plugs 6 & 12. I just split the power coming out of plug pos. 6 to pins 12 & 6 on the ABS connector; these are the pins that get power to the relays/circuits, which you can see at the top of the wiring diagram at the beginning of the thread.

                    With the relays and power connections jumped, all that's needed to actuate the solenoid valves is to ground the pins for the solenoid valves in the ABS connector (at this point, I left the jumper for the ABS pump relay unplugged from one of the plugs, either 87 or 30, it doesn't matter which).

                    Since the pins in the E30 ABS unit are pretty-good sized, I think I was able to find a female plug out of my Radio Shack connector selection to fit pretty well without having to go to great efforts to make something fit. Come to think of it, I think I actually used a small alligator clip that had a plastic cover that would cover the full length of the clip & clip jaws. I ran a pretty good length of wire out from the plug for the solenoid pins as I needed to be able to cycle the solenoids while sitting in the car.

                    The wiring diagram shows the solenoid valves are ABS connector pins 1, 3, & 5. The numbering pasted in on the 2nd pic of the connector (1, 2 & 3) at the beginning of the thread are the wires for the solenoid valves, but do not correspond to the wire diagram or connector numberings. Both the plug and connector have numbered positions molded in that are easily seen, but you may have to look closely (they're small - see attached pic for reference).

                    In this case,
                    pictured 1 = wiring diagram connector position 1,
                    pictured 2 = wiring diagram connector position 3,
                    pictured 3 = wiring diagram connector position 5.

                    To start, I plugged onto connector position 5, the rear solenoid valve.

                    Then I connected the wire to one clip on a starter switch -

                    (one of these: http://www.harborfreight.com/12-volt...tch-35448.html)

                    and the other clip was grounded to something, anything grounded will work - shocktower mount bolt, etc.

                    For the ABS unit to get power, the ignition switch needs to be on, I forget if in the accessory or run position - anyway, either one or two clicks forward, no need to turn to "start" position which would crank the starter & start the car.

                    With the ignition switch on, you should be able to push the button on the starter switch and hear the solenoid valve click. The starter button is spring loaded, so pressing and holding the starter button closes the solenoid valve and holds it closed, until you release the starter button. Multiple button pushes = multiple clicks.

                    Theorizing that normally, the ABS pump only operates at most for a few seconds at a time, I left its relay un-jumpered so it would not be running any longer than necessary.

                    The bleeding process, it might be handy to have a second set of hands, but that was not an option for me, so I had to procedurally compensate, but I think to no ill effect.

                    At this point, the valve relay is jumpered (87 & 30), the ABS pump relay is, uh, half-jumpered, the power is jumpered (connector 6 to pins 6 & 12), and connector pin 5 is connected to the starter switch, and the other starter switch clip is to ground.

                    Then, pressure brake bleed as normal; suck old fluid out of reservoir, fill with new, connect & pressurize pressure bleeder, and bleed the rear passenger side caliper until you have new fluid at the caliper. Once new fluid is to the bleeder bottle, I shut the caliper bleed, went up, and checked the pressure level on the brake bleeder; re-pressurize if necessary. This is where help would be, uh, helpful - not having any extra hands to solicit, I made sure I had enough fluid in my bleeder bottle (a Bavauto brake-bleeder bottle, but anything might work) to ensure the end of the brake bleeder hose was thoroughly and completely submerged in brake fluid, and the bottle would stay in position and keep the end of the hose submerged.

                    Then, I cracked the bleeder open, went back to the front of the car, plugged in the ABS pump jumper (87 & 30, and if in a bit of a hurry, don't mix them up), which started the ABS pump running. Then, I hopped in the driver's seat and carefully grabbed the starter switch (remember, with long wire leads to keep in reach while seated in the car and not pull the clips off whatever you're using for a ground point or the connector-pin plug wire.

                    With the ABS pump running and the bleeder having been cracked open, brake fluid is being pushed through the system. A few clicks of the starter switch to cycle the solenoid, and then, press the brake pedal down to additionally flush the system. While pushing the brake pedal down (not too fast) cycle the solenoid repeatedly (ie, push the button a whole bunch of times rapidly) to your stop point pushing down.

                    If you have an old/older brake master cylinder, it's probably not a great idea to push the brake pedal full travel all the way to the floor, as you run the risk of blowing the master cyl. internal seals if there's any corrosion/rust/etc. on the master cyl. piston area that moves through the seals. If that's the case, push your brake pedal only as far as you would when driving the car.

                    Having reached the stop point, I released the starter button to ensure the solenoid was open, and let the brake pedal come back up, again, not too fast. The reason for keeping the bleeder hose submerged is to not risk drawing any air back into the bleeder line. If you have someone helping, they can close the bleeder when you say stop at your stop point, & you can then let the brake pedal come back up - and, they can observe any air bubbles coming through the bleeder. If you don't have anyone helping, recording some video of your bleeder hose while you're in the car might be used so you could observe if any additional air is pushed through the lines.

                    Again, not wanting to risk over-running the ABS pump (not sure if that's possible or not, but, hey, just in case), I repeated this bleeding process pushing down the brake pedal 3-5 times, each time cycling the solenoid while pushing down. When done with that corner, it's hop out, close the bleeder, and pull one end of the ABS pump jumper wire. Check bleeder for pressure & fluid level, and repeat the same process for the left rear side. As you go, you'll feel the solenoid closing, as the brake pedal will stop moving down as you're pressing.

                    When the left rear is done, then move the solenoid plug to connector pin #3 - re-check the bleeder fluid and pressure level, and repeat the bleeding process as described for the front passenger side caliper. Finally, move the solenoid plug to connector pin #1, and repeat the whole bleeding/cycling process for the left front (driver's) side.

                    After bleeding/cycling each corner, turn & remove your key from the ignition, undo the bleeder & get all that back together and back at the right level, etc. (I presume that's covered thoroughly elsewhere in other diy's), undo the jumper wires, plug the ABS connector back into the ABS unit, secure the cable clamp and screws, plug the relays back in, and secure the relay/connector cover to the ABS unit. The only thing I can think of I might be forgetting is if there's a release clip on the E30 for the connector; there is for the E34, it might have to be pulled or whatever before being able to pull the connector free. In any case, that should be easy enough to see when removing the cable clamp and prising the connector free.

                    This can take some fluid, so 1 liter may be cutting it too close - better to use 2 liters in the bleeder than risk running out & putting air back in at the top end, which obviously would be exactly what you wouldn't want to do, and require re-bleeding.

                    Barring any problems with caliper pistons sticking, poor pad performance, or the like, this is, as far as I know, just about all you can do for a really thorough brake bleeding. If you get good pedal feel after this, then going forward, pressure bleeding normally is likely to work just fine.

                    I know the diagram is for the E30 M3, but comparing the diagram to that in the E30 ETM (electrical troubleshooting manual) I don't see any difference, it looks like all the E30 ABS systems are the same, 3 channel. Comparatively, the E34 ABS system is 4 channel (ie, has 4 solenoids and separate actuation for each caliper).

                    Googling should turn up places that host .pdf versions of the E30 ETM - I can try and dig up one or two if necessary.

                    Looks like this was a thread from the dead recently resurrected, thought maybe my experience might be helpful. Cycling these early ABS systems takes deciphering the wiring diagrams and a bit of wiring effort, but otherwise is straightforward - I've been wondering for years how to do it, with what's been posted elsewhere, figured this much out, hopefully of help to others.

                    A pressure bleeder is a must for this procedure, the positive pressurization of the brake system I think is far more effective for getting any air out vs. something like a vacula.

                    Disclaimer: this worked for _me_; ymmv. Plugging & jumpering wirings opens up the possibilities of human error with potentially shocking/fiery results, so double-check everything for yourself and proceed with caution. Adding fuses to any wires/jumpers etc. _may_ be a good idea just in case of crossing something up, although I didn't bother. Remember, it's the internet & it's free, sometimes you get what you pay for - if there are any errors, they are unintentional, but I'm not making any guarantees either!
                    Attached Files
                    Last edited by BMER; 04-07-2014, 11:46 PM.

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                      #25
                      Awesome. Dude you rock. Can't do this for awhile but I will try eventually and report back.

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                        #26
                        A couple of addendums - I didn't broach removing the back of the wire harness connector; It would be possible to pull the cover as shown in the pic at the beginning of the thread, jumper both relays, and perhaps a small alligator clip (wired up with a long lead) might adequately grip the top of the plug connectors for the starter switch. The potential issue with pulling the connector cover off might be it re-installing as securely as originally. Perhaps the OP might comment if there were any issues with the cover going back on and being secured/sealed as well as it was originally. I could see potential for an issue with the old & possibly-now-fragile original plastic.

                        As an aside, if your connector to the top of your brake reservoir cap for the fluid-level sensor is intact, it may be best to just leave it attached. I tried to pull the wire off my E34 and it just crumbled between my fingers - oops.

                        The solenoids apparently take a little power - I initially tried a much smaller switch and it quickly got too hot to hold after repeated solenoid clicking. The starter switch handled the task without a problem.

                        The other thing that might be done is recruit _two_ friends, and have one tap the ABS unit while bleeding and the other friend tapping the caliper while bleeding, just to cover every base for knocking out air bubbles.

                        Found a picture of my bypassed ABS unit before putting everything back, with the relay/connector cover removed, and the cable connector removed from the ABS unit. Mentioned earlier, but pin numbers are molded in next to the pins, although not viewable in this pic. '87 325is, prod. 5/87 - for me, the cruise control is not in the way for accessing the ABS unit.

                        Bypassing the ABS unit yielded a rock solid brake pedal; the problem though was, not surprisingly, no ABS. I didn't have much problem managing front lockup in the dry, but nearly every heavy braking application ended up locking up the right rear wheel with accompanying big cloud of smoke off the rr tire, flatspotting every time. Corner weighting might have helped, but putting the ABS back was a better option.
                        Attached Files
                        Last edited by BMER; 04-07-2014, 11:40 PM.

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                          #27
                          So I tried this last night. No dice, still spongy. I also tried activating each solenoid individually to isolate each circuit from the master cylinder and see how much sponginess disappears. Seemed about equal for each circuit, so if there is air it's in each circuit. I'm going to put the PFC11s in and hope that I just needed better pads, though it still happened with HP+ so I'm not holding my breath.

                          Perhaps this is the god of fiscal irresponsibility's way of telling me I need a 4 wheel bbk and dual master cylinder setup.

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                            #28
                            Well this thread just answered a bunch of my questions. I even vacuum bled my system and I couldn't get rid of the spongy pedal. Some of this stuff really needs to be stickied.

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                              #29
                              Thanks- this thread helped me a lot!

                              This was really helpful. What I ascertained in the end however, is that one (likely two) solenoids were faulty.

                              In this ABS system- there are no warnings for bad solenoids or pumps. Only bad relays or wheel sensors... In reply to a Porsche thread on rebuilding these pumps for the 964 I finally figured it out... Here's what I wrote to them:

                              We have a similar set up on the BMW e30 I race, and we've been having massive issues with our ABS- normally the front right locking up although sometimes the left too.... (it's a left hand drive car and the front right has about 170 lbs less weight on it).

                              What made this really confusing is that we could feel the ABS working in the rear, but we couldn't understand why the fronts were locking up- really hard. So much so we flat-spotted two tires at the last race :(

                              The symptoms are the ABS system appears to be perfectly functioning- no warning lights. Pulling a wheel sensor triggers the light immediately. I put in another controller (I had spare) and no difference.

                              I wired in some 12v LED's to the channel activation (FR, FL, R)- I could see when the wheel was locked up, the ABS system thought it was trying to unlock it... so definitely not a sensor or a controller issue.

                              Pulling off the connector at the pump and manually activating the pump and each solenoid didn't yield any results (although it has fixed other peoples issues in this thread).

                              Here's a really good e30 thread with all the details you need to cycle your pump: http://www.r3vlimited.com/board/show...=251112&page=2

                              Finally I bit the bullet tonight and replaced the pump with a spare... Early testing around the streets appears to show that it works! I need to get it to the track to really see, but no wheel locked up for more than about 1 meter.

                              So, if you're having ABS issues in 964's, e30's or any of these early Bosch systems, there is no sensor to detect whether the solenoids or the pump is firing. The test circuits are for whether the relays are working.

                              Here's a diagram for the e30 pump wiring- I'm assuming yours is similar:



                              In answer to a previous question, if the system is off, my understanding is that it has no effect on the brakes whatsoever... what is interesting however if there's a warning light, it does hold the solenoids open but keeps the pump off. FWIW I would try both modes to see if that makes a difference. Disconnecting a wheel sensor is the easiest way to make it go off.

                              ABS has become a way to cheat at brake balance, so what we found was that when it was going wrong, it really goes wrong since the wheel that shouldn't be getting full force, is!

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                                #30
                                Does someone have an updated visual of the E30 ABS unit and how to activate it by jumping with wires? I need to activate mine. I have hard pedal, front brakes are fully bled but no fluid going out of the ABS unit to the rear brakes. Wanted to try and unstick valves with activating it.

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