E46 M3 brakes don't feel right? How to tell if it's the ABS/DSC unit

The brakes just didn’t feel right.

Not a sinking pedal, the usual sign of a failing master cylinder, but something just seemed amiss with the brakes on our E46-chassis M3. The pedal felt soft but didn’t go all the way to the floor.

We figured we had two options: ignore it (hey, the car did stop) or investigate further. …

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This might be a good reminder that this E46 M3 is 20 years old now. Still not old enough to legally drink - but it's getting there.

This one turns 21 years old this month!

I think the bigger lesson here: Sometimes I really wish we had a good, dedicated BMW shop here in the greater Daytona area.

But wait, you say, Daytona does have a BMW shop. I have driven past it. 

So far, two for two, they couldn’t help.

Rod bearings? Yeah, not interested in doing that job.

Reprograming the ABS/DSC unit? Yeah, we don’t have the computer for that. 

End result: I get to do the legwork while working remotely with BimmerWorld and Rennie at Redline Bimmers, two dedicated, helpful partners. When I have questions, they’re quick with an answer. A+ partners on every level. 

If only they were a bit closer to us as I came this close to driving to South Florida for the five minutes Rennie needed to reprogram the ABS/DSC unit. 

For those sorts of prices/headaches, I'd just crack open the hydraulics. My guess would be a bad seal that jammed one of the solenoid valves.  Unless it's sealed in some special way (which I know the Germans love to do), seems like it'd be easy to find/replace.  

Rennie said the device can’t be opened. Well, technically I guess you can open anything, but he meant in a non-destructive way. I thought about having the unit ultrasonically cleaned, but simply replacing it seemed like the quickest option once logistics were thought through. 

If that is a M3 MK60 ABS, it is in high demand.  It has become a popular swap for track cars.  It can function standalone and some the M3 units can be flashed with Motorsports software.  Your old control unit might still have some value.

I had a similar thing happen on my 03 Zo6 ABS unit.  There is a company that fixes the electronics but mine was determined unrepairable.  No units in all the usual places so a junk yard used unit was bought and installed.  Luckily it worked but a lot of unknowns and stress in the search and install hoping for the best.  With as cheap and multiple sources of electronic fuel injection, aftermarket ECUs etc are I hope the industry fills the ABS gap with programmable designs that aren't $3-4k.  Even electric power steering aftermarket is gaining ground.  Brakes and ABS for older non ABS equipped cars, track cars and ABS equipped factory cars can all benefit from some aftermarket support that doesn't break the bank.  AEM,Motec,Holley etc.. should be able to make a unit that is programmable like their ECUs and can be swapped in place of a OEM ABS unit.

This is why 'older' German/European cars seem to just fade away from sight.  Yes, it's not just limited to only them, but you get the idea.  If parts were 1) available 2) didn't need 'special' programming and 3) were within the normal owner's budget, then maybe, possibly, potentially, on a good day, one just might see more European cars here as they get older.  Also, I need to add one thing: the added complexity of BMW's systems (like the cooling system for example) is ridiculous in my opinion after owning a mid-2000's 328 and fiddling with all of the O-ring junctions and snap-together foolishness.  The end result is less of them on the road because no one wants to mess with them much anymore. 

Zeitgeist said:

I had a similar thing happen on my 03 Zo6 ABS unit.  There is a company that fixes the electronics but mine was determined unrepairable.  No units in all the usual places so a junk yard used unit was bought and installed.  Luckily it worked but a lot of unknowns and stress in the search and install hoping for the best.  

Glad to hear it wasn’t just me. 

DavyZ nailed it.  This is why you can buy very nice, mid-mileage German performance cars for small enough money to actually make me feel sorry for the poor original owner's eye watering financial depreciation.  So for the "normal" (non GRM) reader, a relatively simple failure can result in junking an otherwise pretty nice car.  Once they are out of warranty - you really take your "chances"!

In reply to J.A. Ackley :Instead it drives you to drink.

In reply to J.A. Ackley :Instead it drives you to drink.

Zeitgeist said:

Brakes and ABS for older non ABS equipped cars, track cars and ABS equipped factory cars can all benefit from some aftermarket support that doesn't break the bank.  

The Continental Teves MK60 and the next generation MK60e5 this article is written about is that unit.  The MK60 M3 units were best, but the non-M3 3 series units work as well. The MK60e5 units are supposed to be even better. You can transplant the ABS unit, wheel sensors, and yaw sensor and add track ready ABS to any car with 4 wheel disc brakes.  I did it in my 1985 Volvo 740 endurance race car. I pulled a unit from a junkyard '05 325 for <$100 and spent another ~$200 on wiring, sensors and 48 toothed wheels.  They even transplant it into C5 Z06s.

20-30/40 yr old cars.
Now u know why Japanese/Korean / English / American cars don't fade away. 

hello, mid yrs 20-3o/40yrs old German, Italian fade into garage ornaments.  Especially German.  

 French, well they are French u know. Only understood by French.  
 

Yeeeeah....I'd love to take this moment to talk smack about German engineering, but there are similar issues with 90's Honda ABS units. Most of the units on Gen 1 NSX, Gen 2 Integra and Gen 4 Preludes are all junk and un-repairable at this point. 

Swap kits exist for the S2000 ABS unit, but it seems car designers in general made these into expensive, non-serviceable black boxes.

I was recently lamenting with a friend about my ABS/DSC woes. He campaigns a C5 Corvette Z06 and owns multiple auto repair centers.

David, he said, I have trouble getting parts for my Corvette.

Just for kicks, I searched for an ABS module for a 20-year-old Z06. Looks like it’s also NLA. 

How many different manufacturers are building abs/dsc units at this point.  Most cars seem to use a continental/teves or bosch unit.  Not sure on the control side how much is manufacture developed & how much is supplier.  So it may be more the suppliers not making the part.  It is to bad, just around the time people are able to get them working standalone for swaps replacement parts dry up.

I was able to save my non m mk60 with a failed pump.  Even though it's not available separately 2 torx bolts hold it to the valve block, so I was able to swap with a working used unit.  My biggest negative against the newer mk60e5 is that the valve block is crimped around the pump making it difficult to repair, the early units had brush issues with the pump motor that led to multiple failures 

I'm surprised at the NLA part, BMW is usually pretty good about keeping parts around.  When I had my E36 M3 I was always happily surprised at what I could get from local dealers, not only did they have some obscure plastic part available, they had it in stock.

Yeah, this is a real bummer about cars with a fair bit of specific electronics.

 If you're adding or updating EFI and it's not tied into other systems, you can always replace the ECU. 

 It's worrisome that this is just the foothills given how much more electronic stuff and how much more integration has happened since this.

I wonder if we'll see a third party version of something like the mk60 crop up. Or whether at some point the only move will be reworking the brake system sans ABS. ECUs can be generic and adaptable. A lot of these other modules, less so.

Jesse Ransom said:

I wonder if we'll see a third party version of something like the mk60 crop up. Or whether at some point the only move will be reworking the brake system sans ABS. ECUs can be generic and adaptable. A lot of these other modules, less so.

An ABS module can be generic and adaptable too.  In fact, that's part of the reason people like the mk60 so much -- it's pretty much the best standalone ABS unit out there that was sold in large volumes.  Yes, ABS works best when it's tuned for the specifics of the car that it's controlling, but there is aftermarket software to allow you to retune the mk60.

The problem with newer cars than that is that the ABS isn't a standalone unit any more, there is a ton of integration with the ECU to enable more advanced features so you can't just plop one down in a different car.

In reply to codrus (Forum Supporter) :

Good point. I guess the thing we haven't seen yet is a generic ABS unit sold as such at non-Bosch-Motorsport pricing.

Fingers crossed something like an optimizable mk60 sold for that purpose crops up. Seems like the dwindling supply might indicate a market, but it's a non-trivial thing.

I'm worried about newer and more integrated stuff, but I also remember the readers' letters to Hot Rod in the early '80s lamenting computers bringing an end to hot rodding... That's different from just not bricking a daily, though.

Hey, if these units keep failing that should drive down the price of an e46 M3 with a bunch dsc/abs lights lit up, right? I'd be very okay having one of these and putting it on track without ABS/DSC.

adam525i said:

Hey, if these units keep failing that should drive down the price of an e46 M3 with a bunch dsc/abs lights lit up, right? I'd be very okay having one of these and putting it on track without ABS/DSC.

You'll need to do some moderate re-engineering of the braking system to run it without the ABS unit.  The stock system has no mechanical proportioning in it, so without the ABS it is very tail-happy under braking.

codrus (Forum Supporter) said:

adam525i said:

Hey, if these units keep failing that should drive down the price of an e46 M3 with a bunch dsc/abs lights lit up, right? I'd be very okay having one of these and putting it on track without ABS/DSC.

You'll need to do some moderate re-engineering of the braking system to run it without the ABS unit.  The stock system has no mechanical proportioning in it, so without the ABS it is very tail-happy under braking.

 

My E28 was the same way on track even though it was one that didn't come with ABS from the factory. Willwood adjustable proportioning valve solved that issue. I'm not claiming the car will be better/faster without ABS/DSC but it would still be fun.