01 z06 rear brakes are locked up, after working on the EBCM.

I had the occasional C1243 and now C1214. Would unstick with the usual tricks (lock up after resetting, 2nd gear with wheels in the air, etc). Became more common. Now 1214 comes on without even having to start the car – so I decided to inspect the EBCM. No obvious broken solder, but I reflowed a bunch, cleaned connectors, etc. Reinstalled and still having problems. I pulled the EBCM a 2nd time and reinstalled.

Now my rear brakes are locked (front are not) and I can’t move the car. I pulled all the fuses, disconnected the EBCM and it still has the rears tires immovable. I bled the rears to where I could hand spin them, and they reseized after a few brake presses.



I assume I damaged one or more of the spool valves or something seized in the pump.

I just ordered a new (used) BPMV and EBCM. I’ll probably sent my old ECBM and BPMV off to ABSfixer.

Any recommendations on a BPMV replacement tutorial of write up that you found particularly good? I ordered a Foxwell NT510 scanner that supposedly has the ABS bleed function.

 

Factory service manual is all I have ever used for routine maintenance.

 

I hope you haven't had to replace too many - but I am hoping replacing the BPMV isn't routine maintenance for most of us!!
I am sure there are write ups out there I couldn't find, but just some notes on my first BPMV replacement:Pretty straightforward, but minor things (room for specific wrenches, hand size) can make it a pain,

1) Remove the intake (throttle body all the way to the MAF).
2) Remove the top radiator line (from driver side top of the radiator to passenger side, just past the throttle body).*The following may be because I have a thick aftermarket radiator, and likely not required, but in retrospect, draining and removing the radiator and fans would help a lot with sticky brake line bolts (allowing longer wrenches), and will keep radiator fluid from dripping on you while you work.

3) Disconnect the grey plug on the ECBM facing the throttle body (flip the grey ‘handle’ part up 90 degrees, and towards the driver side, then pull the plug towards the passenger side).
4) Push/tuck the power steering rubber line (1/2 inch?) behind of the EBCM/BPMV (towards the back of the car). This allows more room for wrenches on top of the BPMV.
5) Loosen all 6 brake lines(4 on top, two on the driver side; 1/2 or 13mm – use a brake line wrench if at all possible). If your wrench slips at all, this can quickly become a nightmare (because of the limited room to reposition wrenches in a tight space). Mark each line (especially the ones on the side) so you don’t accidentally reconnect them improperly. I used a paint marker with (I, II, III, IIII, -, x), as sharpie can get dissolved by brake fluid.
6) Remove the top 2 brake line fittings (top of BPMV) closest to the throttle body first. This may require some patience, very short ½ /13mm wrenches, or ratcheting brake line wrenches if you have them. Once the two lines are removed, they can be pulled up, to get wrenches on the other 2 brake lines on the top of the BPMV (towards the fender). When all 4 lines on the top are disconnected this allows more room for the 2 lines on the driver/fender side of the BPMV.
7) Remove the 2x ½/13mm lines on the driver/fender side of the BPMV. Follow the wire from the small round grey plug (fender side) and disconnect at the black connector (about 6 inches of wire away). The grey plug should be reconnected on the new BPMV prior to installation (as the brake hardline can get in the way if you try and do it later).
8) Remove the 2x 15mm(unsure of exact size?) nuts from the (insulator)mounting studs on the side of the BPMV (one facing the front, one facing the rear).
9) Lift the BMPV (and connected ECBM)up off of the bracket (less than one inch), then pull out the mounting stubs out of the BPMV (the 2x things you took the 15mm(?) nuts off of). This allows more clearance. Move the BPMV/ECBM towards the passenger side, until you have room to pull it directly up (stock radiator may make this easier).
10) Install in the reverse of removal. Slide the BPMV and attached ECBM in from the near the throttle body, pop in the mounting stubs. Install the 15mm(?)(insulator) nuts on the mounting studs- then plug in the round grey plug (fender side) before starting threading in the brake lines. I made sure to pour brake fluid into the the open sockets when I was reinstalling the lines (2 on the side 1st, then two on top towards the fender, then 2 on top towards the middle) to try and minimize air intake. I have no idea if this is useful- as you’ll probably have to bleed anyways. Aligning the threaded inserts while attached to the hardlines can be MAJOR pain in the ABS, so be patient, and try and use one hand for threading, and maybe the other hand for wiggling/bending/twisting/witchcraft of the hardline to get the threads to align perfectly. Do not try and force the lines as these are the absolute last thing you want to cross thread.
11) Make sure the major ECBM grey plug ‘handle’ (misssing in my pics) is flipped up (throttle body side), then press in the larger connector, and press the grey handle 90 degrees down. Also, connect the grey plug wire’s 6 inch plug into the black connector near the driver side fender.
12) Reinstall radiator, or top radiator hose, and intake tubing (don’t forget to plug the MAF back in).
13) Proceed to ABS flush (I used a Foxtel Tech 2 clone that I can give directions on (very easy), but this is covered elsewhere.

**I’ve only done this once, so some of these may be terrible ideas, or specific to my car and or tools available**

 

Unfortunately........most of us. I have done it many times on friends C5s, with most just being EBCMs, but at least 3 were BPMV as well. Did my EBCM in 2012, and my 25 year old BMPV is still hanging in there. For those of us that are original owners, we went through this 10-15 years ago. Be thankful you have an 01, and parts are plentiful/repairable.

 

Ouch- I knew the ECBM's were frequent issues but didn't realize the BPMV's were as much. I'll definiteley have my old one rebuilt and keep it as a spare.

 

They generally aren't as problematic as the cracked solder joints that are very common in the EBCMs. That said, and no offense but are you sure the problem isn't related to work you did in the EBCM? 1214 is a solenoid code which is on the daughter board that's inaccessible. But I believe the driver transistors are on the main board. 1243 is a stalled pump motor, which won't cause the rear brakes to lock (but still isn't good news).

Assuming you're speaking about the BPMV, I'd be interested to hear if you indeed find someone equipped to do that. In inspecting my dead unit (pump motor was burned up) they don't appear to be very serviceable. Many of the body passage plugs are swaged in place and only a few pistons in the bottom appear to be potentially removeable without drilling.

Even the pump motor mounting screws (5 x 75mm if memory serves) were installed with permanent threadlocker and can only be removed by drilling the torx heads off and then heating the remaining stud. Since the 1243 code was the only thing wrong with mine I was hoping to find a new / used replacement motor, but after a good bit of research that seems a very tall order. The only other vehicle I found that part # motor on was a 2000s era Porsche.

 

I probably did damage some stuff. I think my pump was slowly dying (recurrent 1243), and that killed the ECBM (very occasional 1214 - that became permanent once I worked on it), but then in removing the ECBM I permanently damaged the spool valves (causing the locked rears).I also had a confounding wiring issue (belt ate the harness to the ECBM, that was repaired, and had a few possible poor solder points in the wiring (break was right by the ECBM plug). The solder joints on the ECBM board near 'usual' relay all looked fine, but I reflowed them (twice).

I am pretty new to this car- and what you mentioned above I was not aware of. I did see that ABSfixer mentioned BPMV repair if you sent in earlier (pre - '01) BPMV/ECBM's as a unit, but I had not looked into '01-'03 specific BPMV repair. If not serviceable (as it sounds) - I may send my ECBM off for rebuild (if they can) and maybe cut open the old BPMV to see what's damaged.

 

Replacing the BPMV/ECBM worked out. Not having ABS for > 6 mos, to track record times is nice.