DSC/ABS Problems

[Mangozac]

Well recently I started getting my first fault with the Z4. The first time I was just driving along and suddenly the dash beeped at me and brought on the yellow DSC and brake warning lights. Consulting the manual I discovered that this indicated a problem with the DSC (traction control) and ABS systems. It's happened a few time since and was really starting to irritate me, since it meant driving like a grandma when the fault occurred (it causes the ABS and DSC systems to completely shut off) :thumbsdown:

Fortunately I had a suitable OBD-USB cable on the way and after a lot of playing around today installing software and familiarising myself with it I have had some success!

Using INPA to read the DSC module error codes provides the following report:

           FEHLERSPEICHER LESEN
           ---------------------------------------
Datum:     14.04.2012 16:48:49
ECU:       DSC_MK60
JobStatus: OKAY
Variante:  DSC_MK60
-------------------------------------------------------------
ERGEBNIS:  2 Fehler im Fehlerspeicher !
-------------------------------------------------------------
5E24  Druck Sensor 1/2 unplausibel
Fehlerhäufigkeit: 1
Logistikzähler  : 9
   Kilometerstand                           63050     km
   Fahrzeuggeschwindigkeit                     50.00  km/h
   Bremslichtschalter                           0.00  0/1
   Bremsfluessigkeitsschalter                   0.00  0/1
   ASC/DSC_aktiv (Tasterfunktion)               1.00  0/1
   Bremsdruck erkannt                           1.00  0/1
   ABS-Regelung                                 0.00  0/1
   ASC-Regelung (BMR)                           0.00  0/1
   ASC-Regelung (AMR)                           0.00  0/1
   GMR-Regelung (GMR)                           0.00  0/1
   GMR-Regelung (MMR)                           0.00  0/1
   CBC-Regelung                                 0.00  0/1
   MSR-Regelung                                 0.00  0/1
   TDR-Regelung                                 0.00  0/1
   SDR-Regelung                                 0.00  0/1
   DBC-Regelung                                 0.00  0/1
   RTA aktiv                                    1.00  0/1
   Run-Up Mode                                  0.00  0/1
   kein passendes Fehlersymptom
   Testbedingungen erfuellt
   Fehler momentan nicht vorhanden, aber bereits gespeichert
   Fehler wuerde das Aufleuchten einer Warnlampe verursachen
Fehlercode: 5E 24 A0 01 09 18 A1 32 28 00 04
-------------------------------------------------------------
5E20  Druck Sensor 1 elektrisch defekt
Fehlerhäufigkeit: 7
Logistikzähler  : 26
   Kilometerstand                           63050     km
   Fahrzeuggeschwindigkeit                     54.00  km/h
   Bremslichtschalter                           0.00  0/1
   Bremsfluessigkeitsschalter                   0.00  0/1
   ASC/DSC_aktiv (Tasterfunktion)               1.00  0/1
   Bremsdruck erkannt                           0.00  0/1
   ABS-Regelung                                 0.00  0/1
   ASC-Regelung (BMR)                           0.00  0/1
   ASC-Regelung (AMR)                           0.00  0/1
   GMR-Regelung (GMR)                           0.00  0/1
   GMR-Regelung (MMR)                           0.00  0/1
   CBC-Regelung                                 0.00  0/1
   MSR-Regelung                                 0.00  0/1
   TDR-Regelung                                 0.00  0/1
   SDR-Regelung                                 0.00  0/1
   DBC-Regelung                                 0.00  0/1
   RTA aktiv                                    1.00  0/1
   Run-Up Mode                                  0.00  0/1
   kein passendes Fehlersymptom
   Testbedingungen erfuellt
   Fehler momentan nicht vorhanden, aber bereits gespeichert
   Fehler wuerde das Aufleuchten einer Warnlampe verursachen
Fehlercode: 5E 20 A0 07 1A 18 A1 36 08 00 04
=============================================================

Yes, it's in German - most of the INPA stuff is in English but random bits are in German for some reason. Fortunately Google Translate does a really good job:

MEMORY READ ERROR
           ---------------------------------------
Date: 14/04/2012 16:48:49
ECU: DSC_MK60
Job status: OK
Variation: DSC_MK60
-------------------------------------------------- -----------
RESULT: 2 errors in error memory!
-------------------------------------------------- -----------
5E24 pressure sensor 1/2 implausible
Fault Frequency: 1
Logistics counter: 9
   Mileage 63050 km
   Vehicle speed 50.00 km / h
   Brake light switch 0.00 0/1
   Bremsfluessigkeitsschalter 0.00 0/1
   ASC / DSC_aktiv (function button) 1.00 0/1
   Brake pressure detected 1.00 0/1
   ABS control 0.00 0/1
   ASC-regulation (BMR) 0.00 0/1
   ASC system (AMR) 0.00 0/1
   GMR control (GMR) 0.00 0/1
   GMR control (MMR) 0.00 0/1
   CBC Regulation 0.00 0/1
   MSR regulation 0.00 0/1
   TDR regulation 0.00 0/1
   SDR-regulation 0.00 0/1
   DBC regulation 0.00 0/1
   RTA active 1.00 0/1
   Run-Up Mode 0.00 0/1
   no suitable error symptom
   Test conditions are met
   Error currently not available, but already stored
   Error would cause the illumination of a warning light
Error Code: 24 5E A0 18 A1 01 09 32 28 00 04
-------------------------------------------------- -----------
5E20 pressure sensor 1 faulty electrical
Error rates: 7
Logistics counters: 26
   Mileage 63050 km
   Vehicle speed 54.00 km / h
   Brake light switch 0.00 0/1
   Bremsfluessigkeitsschalter 0.00 0/1
   ASC / DSC_aktiv (function button) 1.00 0/1
   Brake pressure detected 0.00 0/1
   ABS control 0.00 0/1
   ASC-regulation (BMR) 0.00 0/1
   ASC system (AMR) 0.00 0/1
   GMR control (GMR) 0.00 0/1
   GMR control (MMR) 0.00 0/1
   CBC Regulation 0.00 0/1
   MSR regulation 0.00 0/1
   TDR regulation 0.00 0/1
   SDR-regulation 0.00 0/1
   DBC regulation 0.00 0/1
   RTA active 1.00 0/1
   Run-Up Mode 0.00 0/1
   no suitable error symptom
   Test conditions are met
   Error currently not available, but already stored
   Error would cause the illumination of a warning light
Error Code: 20 5E A0 07 1A 18 A1 36 08 00 04
=============================================================

To in summary the report says the following:

1. Pressure sensor 1 (of the two pressure sensors mounted on the bottom of the brake master cylinder) has been exhibiting electrical faults
2. Pressure sensor 1 or 2 has been "implausible". A bit of a cryptic error - I'm guessing that means that the sensor has given an out of range output. How this differentiates from the other error code I don't know. Maybe it's simply intended to be a "universal code" that then points you to the other two?

The most obvious solution would therefore be to replace sensor 1. RealOEM lists the DSC pressure sensors as part number 34521164458, which TheBMWPartStore lists for $96.12, so not hideously expensive. But I find the intermittent nature of the fault to be concerning - it's possible that the fault is with the physical electrical connection to the sensor, so perhaps I might clean the sensor 1 electrical connection, reset the fault and see what happens?

One small problem though: I can't find any identification of which is sensor 1! :roll:
The master cylinder does have a marking above each sensor: "H" above one and "V" above the other. Do these somehow translate to "1" and "2" in German? The TIS even refers to them as the H and V DSC pressure sensors!

So can anybody offer any suggestions?

 

[bcworkz]

Vorne Hinten = front rear (brake systems, not necessarily physical position)
Doesn't help eh? I would assume #1 is forward of #2 if you find no other clues.
If all else fails, and the replacement doesn't work, swap the old part back in and replace the other one.

 

[Mangozac]

Aha - I knew it would be some German!

I would assume #1 is forward of #2 if you find no other clues.

That would certainly make some degree of sense, but alas in the depths of the TIS I found the specification contradicting that idea:



As you can read from the explanations, Sensor 1 is the rear axle pressure sensor, and Sensor 2 the front.

So now that I know which is which, I might do some playing around with the connections before I go splashing out on a new sensor. They are capacitive style sensors and I just don't feel that the likelihood of the sensor itself becoming intermittent is that high. Will report back on it

 

[lopj]

Hi there,

I'm having very similar issues with my dsc mk60 on a 2005 m3, 40,000km.

Inpa is showing :

5E21 pressure Sensor 2 electrical failure
5E24 pressure Sensor 1/2 not plausible

I find my issue to be heat related, when it's hot i get the dsc and yellow brake lights lit and loss of dsc function.

As it's been raining in Sydney and quite cool, I haven't had the issue turn up over the last few days.

As such i've been thinking it could be the dsc electronics module, which is known to go bad on e39(e.g bosch 5.7) and e46(including mk60-teves).

Apparently it could be:

wheel speed sensors
steering angle sensor
teves mk60 control module (or the attached hydrolic unit-which includes pump)
pressure sensors
battery/alternator- voltage


Is heat a factor in your problem?
I'm trying to decide whether to change the pressure sensors or the module itself.

Interestingly, one of my pressure sensors is silver in colour ,and the other a brass like colour.

 

[gazrobbo]

I had exactly the same last year but it was sensor number 2, the light came on severall times, BMW advised me to 'leave it and see if it goes away' which I did and it went away! not had a problem sinse and that was over 6 months ago

although I did clean the wheel speed sensors, not sure if this actually did anything though as they werent giving the fault.

 

[Mangozac]

Hi Lopj I'm sorry to hear you're having the same issue on your M3 - I'd certainly be even more worried driving around with ABS and DSC functions disabled on a powerful car like that! Very interesting that it uses the same DSC module as the Z4 (the Mk60 Teves). How long have you been having the problem?

I can't say I've noticed any correlation to temperature: the first time the light came on was a mild temperature (and some rain). The second time was highway driving at night (on the same day) and the last time I remember was Easter long weekend, which was the only time I can say that it's been "hot" when the problem has shown up.

God I hope it's not the DSC electronics module. That sounds very expensive to replace (and I expect would require a lot of recalibrating too).

If the DSC module is reporting a fault specifically with the pressure sensor I can't believe the fault could actually lay with one of the other sensors. That brings it down to 4 possibilities:
1. The pressure sensor as reported by the fault code
2. Wiring between the DSC electronics and sensor
3. The DSC electronic module
4. Power supply Voltage

The other day I reset the fault codes and had a play around. I had INPA running in sensor monitoring mode where it has the little bargraphs for each sensor. I played around with the brake pedal, watching the pressure display go up and down - all good. I then jiggled around the connector on the pressure sensor (I couldn't work out how to disconnect it actually, and didn't want to break it trying) in the hope that a dodgy connection might flag a fault. Afterwards I checked the fault memory and still nothing. The entire system didn't miss a beat.

Something I haven't mentioned yet is the fact that I know my battery is in the latter stages of its life. The car still starts fine but it I leave the ignition on for long the battery flattens very quickly. I don't know if the DSC module would flag a power supply fault before the voltage got low enough to effect the pressure sensor, but while the car is running (which is when the DSC system shuts down) the voltage should be fine because the alternator has things topped up. Plus I would expect anything voltage related to effect both pressure sensors, not just the one...

Similar to what Bcworkz suggested above might I propose the following diagnostic procedure (for both of us to try):
Pressure sensor 1 and 2 are identical (I just confirmed that the same is true for the E46 M3). Since the error codes are clearly identifying which sensor is giving the problem, then if we swap the two sensors over and clear the errors we should see the error code come up for the opposite sensor position. This will identify whether the source of the problem is the sensor itself or the DSC Mk60/wiring/etc. (if it's the Mk60/physical connections then the same error code will appear). If this experiment proves it's the sensor then you can simply pick up a replacement for $100.

I assume you've got a copy of the TIS? If not send me you VIN last 7 digits and I can send you instructions for the sensor removal procedure (so that you don't end up with brake fluid everywhere ).

The different sensor colours should be nothing: just batch to batch variation - they are probably both the same material except one has been plated.

I had exactly the same last year but it was sensor number 2, the light came on severall times, BMW advised me to 'leave it and see if it goes away' which I did and it went away! not had a problem sinse and that was over 6 months ago

Interesting. Mine hasn't been a problem since Easter and my driving habits are no different, so maybe it's gone away for me too
I certainly don't like just sitting back and hoping it never comes back though :x

 

[lopj]

Hello,

I should point out that at the present time my ABS works, and it's just the DSC function that disables when I ge the two evil lights

Another reason that i have read for the two lights has been simply low brake fluid in the reservoir. Worth a shot, but didn't work for me. Perhaps it might be air in the DSC system? I'm having some work done on the car soon so i'll get a brake flush included and see if it makes a difference.

Thanks for the offer for TIS but I have access to it already

I'm a little reluctant to tackle the changing over the pressure sensors 1 to 2, as it would require me to remove some hydraulic lines on the master cylinder beforehand, for access. I don't have access to a pressure bleeder post work.

I managed to remove the connectors from the sensors by pinching the top of the connector with my thumb and forefinger, and wriggling it off simultaneously(which lifts the connector above a tab, which is holding the connector in place).

At that time i also removed the connector for the DSC electronics module by lifting up the connector, and inspected the pins. Everything seemed fine.

INPA Shows that my pressure sensors are functioning when I depress my brake pedal, and they seem to fluctuate together more or less. That is the reason I am doubting it is the sensors themselves.

I haven't had the lights come on in a few days, and again it has been cold here. I'm hoping it's not my module, which is expensive and requires coding to the car...

I'm going to try and see what DTC's pop up, and diagnose the problem a bit more before laying down my hard earned...

 

[Mangozac]

To be honest I have ni idea if the ABS works when the lights were on - like I said in my first post it caused me to drive like a Granny! But from what I read of the manual the entire DSC/ABS system shuts off if there is a fault (since they are the same system).

First thing I thought of when it happened was low brake fluid, so checked it as soon as I stopped the car and it was still full to the max level.

I had the same results when monitoring the sensors in INPA, hence why I'm also doubtful that the problem lays with the sensor itself. Thanks for the tip on removing the connector. I might have a play again on the weekend, disconnect the sensor and see if the same error code is flagged. It would be preferable if it was the sensor, since that's relatively straightforward and cheap enough to replace!

Well it sounds like we're going to both leave it for the time being and see what happens. If the fault returns again I'll definitely get more "aggressive" with my diagnosis and try the swap over test I described in my previous post. Like I said that will pretty much guarantee if the fault lays with the sensor itself.

Please keep me posted of your progress - either in this thread or replying by email - and I'll do the same

It's been fantastic having somebody with the same problem just to discuss things with!

 

[lopj]

For sure, it would be great to keep each other posted on progress and findings. I have asked a m3forum member about a similar problem and he resolved it by clearing DTC errors a few times, cleaning ABS sensors, and apparently the problem went away- and has not returned for 2 years.

That would be best case scenario for us Otherwise it's one of the sensors or the module. I haven't seen my two lights for a week now, but i haven't driven my car much and it's been quite cold(which seems to affect my particular issue)...

Here's a recent post on m3forum: http://www.m3forum.net/m3forum/showthread.php?t=404087

 

[SGR1913]

I had to replace exactly the same parts on mine. Looking through my bill, i payed 93euro labour plus parts at a bmw main dealer.

Mine was intermittent as well, but it was really starting to annoy me so decided to have it fixed. 1yr later not had any problems....

 

[Mangozac]

Lopj: I read on your other thread that you recalibrated the pressure sensors. Do you think that that really helped?

SGR1913: How often was the fault occurring for you?

I've still not had the fault since. It does worry me when I'm driving "spiritedly" though. Like what if the system detected the fault and decided to disengage during some hard cornering, shutting off the driving aids? While I'm pretty familiar with how the Z4 behaves in DTC mode, I've got pretty much zero experience with unassisted RWD...

 

[SGR1913]

Mine was occuring more or less every day, but generally after 30+ minutes driving. Short trips it never happened, and when it did occur, turning the ignition of and on x times seemed to reset it...

It was highlighted on the 2year safety inspection (equivalent of the UK MOT) and given the cost even at a main dealer wasn't too bad decided to have it fixed.

I lived with the fault for over a year before finally deciding to get it fixed.

 

[lopj]

Hi Mangozac ,

Not sure if recalibrating the brake pressure sensors has worked, but all i can say is that i haven't had the fault in a few weeks now. I would say it can't have hurt to recalibrate them. Perhaps over the last 5 years they fell out of calibration? who knows...It was easy to do so i did it i suppose.
For me I have to wait for the weather to get warmer to be certain the errors aren't coming back. In my case, I'm considering fabricating a cover for my dsc module area, so that it is a little better insulated from engine bay heat.

I'm quite familiar with my cars handling without dsc, as i've driven a few rear wheel drives over the years which didn't have this safety net.

Though I am worried, because at times I do lean/rely on it, especially when wet, and if it were to disable mid intervention.... that would be my main concern.


Hello SGR1913,
Did you replace just the one brake pressure sensor for 93Euro? or did you have both done at together?

 

[Mangozac]

SGR said 93 Euro plus parts so I would expect the total cost to be more like 200 Euros. The problem happening daily is a far cry from what we're experiencing though!

Indeed recalibration can't hurt. It's entirely possible that the sensor may have somehow drifted out of spec in its lifespan so I guess a calibration sequence could account for this. It's a shame that the fault code doesn't specify how the sensor gave a faulty signal (i.e. no signal, too high, too low, etc.).

It would be interesting to find out what the system would do if it detected the fault while it was intervening. Surely in the interest of safety if would adopt a more failsafe mode of operation at least until that intervention had completed, at which point it could shut off completely?

 

[Gerry]

Iv had the same lights coming on intermtitently , the car can run for months with no warnings lights . then these lights can come on 3 days in a row ,then wont come on for months. I have noticed that they only appear when in stop start traffic at lights or a junction ,ie the car is crawling verry verry slowly .like the previous posts i feel it is one of the brake pressure sensors,however the fault has is so intermitent I havnt spent the time to fix it. The new mot rules will put a change to that . now I will need to get it fixed , in case it happens during the mot

 

[bcworkz]

Hi Gerry, it may very well be one of the sensors, but it could be a number of other things as well. You'll need to retrieve the actual errors with INPA or DIS to have any clue as to what the problem may be. Even then, it is a clue and not necessarily the true fault. The errors should be stored whether the lights are currently on or not.

 

[Gerry]

Much of the technical and theory stuff on the previous posts is way over may head ,however I can take bits of and put new bits on . The intermittent nature of the fault is most frustrating. Ill try an retrieve the faults .

 

[thepits]

You'll need to retrieve the actual errors with INPA or DIS to have any clue as to what the problem may be. Even then, it is a clue and not necessarily the true fault. The errors should be stored whether the lights are currently on or not.

Guess what?

Yesterday, whilst driving in the town, I had the handbrake light [in RED] and the DSC warning ! light come on.

This morning when I went out, just after starting her up I got a 'bong' and the handbrake light changed to AMBER [DSC ! still on].

Stopped at the shop, turned off / locked her up, when I returned and started her up both lights now out!!

A quick play of the DSC button appears to show that all is working again.

Popped into an Indie and also a Dealer to see cost of diagnostics [£70 - £80 to find the error codes], and they both had a different idea on what it could be. The Indie suggesting the DSC sensors whilst the Dealer said it could even be the ABS sensors. :?

Is there anyone [fairly] local to me [I'm in Cheltenham] who has the s/w so we can check it out a bit cheaper? :? I'd come to you.

Thanks.

 

[Don Gilham]

I've got an 08 plate 3.0Si Roadster, 66000 miles. These two warning lights have appeared, and my local BMW dealer has the car.

Just had a call, DSC control unit needed, cost of £2400 !!!!!!!!!!!

This is plainly ridiculous on a make of car that is SUPPOSEEDLY top quality.

I am taking the matter up with BMW if they don't fix in on "good will"

 

[srhutch]

If you have time you might want to look at this

http://www.ecutesting.com/bmw_common_ecu_failures.html