2008 BMW 335i E92 DSC/ABS issue, need help

[greg328]

My 2008 335 coupe is exhibiting some dangerous behavior, and I'm trying to trace the issue. When I press my brake pedal full strength, either at rest or moving, the front brakes lock and the car cannot be moved. This has placed me in harm's way more than a few times. I have learned to not lock the brakes, but in some situations on the road, I have to.

I get a DSC malfunction window on my nav screen, and the typical dash warning lights. The only solution is to turn off the car and wait 5 to 10 minutes, and the front brakes will loosen allowing car to be driven as normal. The weird thing is, after I power cycle the car, my dash warning lights go away. So I don't know exactly what the problem is, I see other posts with other DSC/ABS issues and dash lights but not my symptoms of locked front brakes.

Since the lights clear after restart, could my issue be improper ABS bleeding? If the DSC pump or motor were faulty, wouldn't the dash warning lights remain until codes cleared?

I'm considering purchasing another used DSC/ABS pump and motor and reusing my module to prevent the need to recode. Of course there's no guarantee the next pump/motor would be problem-free!

Can anybody offer any insight into a possible resolution? Maybe I just need a dealer brake bleed to make sure the ABS pump is bled properly. Could that possibly cause my front brakes to lock and stay locked, until they release in about 10 minutes? Remember, they only lock when I activate ABS. I can create the problem in my driveway, parked, by just pressing the brake pedal at full strength.

Thanks,
Greg
Houston, TX

[floydr]

The control valve body has a sticking valve(s). Needs a re-build. New ones are quite expensive, there's a rebuild option - I know that the bimmerfest E46 forum has it posted somewhere.

[greg328]

Hmm.. I thought th.at might be a possibility. I'm handy with tools and could remove my assembly no problem. Is the kit readily available for a decent price? I'll try a search on here but if anybody can provide a link I'd appreciate it?

[greg328]

Well, a quick search showed Turner Motorsports has a DSC repair kit for $1000. No thank you. It includes a new module, which I don't think I need.

Based on the fact that my dash warning lights clear upon restart, is it safe to say my module is probably ok? My symptoms seem to indicate a mechanical issue, sticking valve in the pump, right?

The pictured repair kit had 12 rubber grommets, that's probably what I need. Anybody know if those parts may be available separately at the BMW parts counter?
Thanks,
Greg

[greg328]

The other solution is to pick up a used eBay assembly for a couple hundred $$. Much less expensive and may be good for parts if nothing else.
??

[floydr]

Try scanning this thread: http://www.bimmerfest.com/forums/showthread.php?t=630933&highlight=abs+rebuild

DSXMachine is a BMW tech at an indy; super helpful guy. This BBI company that he gives contact info for does them cheap.

[greg328]

The control valve body has a sticking valve(s). Needs a re-build. New ones are quite expensive, there's a rebuild option - I know that the bimmerfest E46 forum has it posted somewhere.

OK, new question: what parts specifically are normally used in rebuilding the control valve body? The rebuild kit from most vendors I'm finding is over $1K. I don't need a new module, just probably the rubber parts. Anybody know a source for just these specific parts? These rubber parts shouldn't be too much $$.... (I hope!)

Or, is it possible that I can disassemble my control valve body, clean it and re-assemble, possibly fixing my sticking valve issue?

Thanks,
Greg

[fun2drive]

You can reuse the valve body and everything should be good. You will get the entire assembly meaning pump-electrical module-DC motor-valve body. It is unusual to have the valve body sticking. Usually too infrequent brake fluid changes cause this.
Modulemasters.com could rebuild yours but based in what you have stated just swapping the valve body out should get you back to full functionality.
Bleed the brakes well and there should be no air in the system. If you can locate some that does coding they can program the ABS to cycle and bleed itself...

[greg328]

Fun2drive, great info, I appreciate it! Does it make more sense just to buy a lowish-mile used assembly off eBay and use the new valve body on my assembly? We're talking the difference between $1000 for the rebuild kit and $150-250 for an entire used assembly.
Further, which exact series brake valve bodies are interchangeable with my 2008 E92 335I? Somebody said any E90-93 from 2006-2012, except for 4-Wheel drive models. Any info regarding this?
Muchas gracias!
Greg

[fun2drive]

The 2007 is different from 2008 on. Go to the parts dept at the dealership and ask but from what I remember the 2008 on should work fine. I see no reason to buy the entire assembly new. I did then repaired my old one which gives me a 100% spare. I do think buying the used assembly and replacing just the valve body is the best plan. Keep the rest of the system because if the DC motor brushes stick they will throw a code and you have a serviceable motor ready to go. Once all done clear codes if any show and worst case the dealer can bleed your brakes ABS included. How ever some have reported that driving on a gravel road and activating the ABS would help bleed that system. I can't verify that however. Many Bosch ABS systems on BMWs are interchangeable again discussing with a good parts guy at the dealership can help. Look for the videos on how to do this regarding removal and replacement...

[greg328]

Much appreciated, thank you. Replacement assembly on the way, will update progress here.
Greg

[fun2drive]

If you have any questions PM me since I have done this and rebuilt my old unit.
Happy to help if you need it...

[greg328]

Thank you, I may be in touch. Any need to relieve brake fluid pressure before assembly removal? I assume if I keep my foot off the brake pedal I can remove the valve body fittings without much loss of fluid; is this correct? I do plan on disconnecting the battery.

[fun2drive]

Read the write ups on this first. A couple videos are out there too. You need some rubber or vinyl caps to cover the brake lines to reduce fluid loss and to keep debris out. You don't really need to disconnect the battery but that is never a bad idea.
Be sure to use flaring tool wrenches not open end wrenches as you can round off the brake line connectors. Any flaring tool set is fine...Harbor Freight or other cheap brand work fine for infrequent use.
Three bolts hold the unit in place. Be careful they can fall down inside and might not make it out on the floor.
Really from a wrench difficulty scale of one to ten I would say this is about a 2 1/2 to 3...

[greg328]

Thank you, I did see that video where he used the little rubber white shelf caps to cover the exposed fittings, will get those. I actually removed this DSC/ABS unit a few months ago in my first attempt to solve the problem. I just exchanged modules but didn't remove the 6 brake lines. Didn't solve the problem obviously!

I have a pretty good idea of what to expect. I do have some flare wrenches as well so I'm good there too.

My main concern is getting a complete bleed after replacement of the valve body. Obviously the replacement ABS valve body is going to have air in it that won't bleed normally. What's the trick? Active ABS on loose gravel and that will cycle the air out of the valve body into the lines where I can then bleed normally at each caliper?
Thanks again
Greg

[fun2drive]

As I Said previously fine someone with a coding software which will has an algorithm which will cycle the ABS and is designed to purge the air out of that assemble. It certainly worth a try on gravel but I have no first hand experience if that will work.

[greg328]

I've got my new DSC ABS hydro unit installed but need to bleed it. Can somebody post a link to or explain the gravel bleed process? Seems you just take the car to a gravel road and activate ABS a few times to push the air out, is this correct?

[fun2drive]

All that does is pulse the ABS not bleed anything. You need to bleed the brakes using pressure bleed or INPA which will bleed each line but again you have to have the bleeder open and shut it flowing INPA instructions. It will bleed the ABS just fine using the manual pressure bleed and a pressure bleeder...