Does DSC off really mean off?

[ptee]

I was noticing something in my coupe whilst driving on snow today...

With DSC on, when going around a corner and giving the car too much gas, it will notice the slippage and cut the throttle almost immediately (as expected). With DSC OFF and doing the same thing, the car would slide a little, but it still felt like the throttle was being limited. I was mashing it after a few "tests"...the wheels should have been easily able to spin, but the RPMs wouldn't go above ~2k RPM.

Not sure if I'm explaining this correctly...

What's going on here? With DSC off, shouldn't it be fully defeated?

[Matt Day]

On the later models (2001-02 maybe?) there was a two-stage DSC with the single press still keeping system involved, but allowing more slip before intervening. If you hold the DSC button down for 10 seconds~, the light will stay on and you have to turn the car off and start in to re-engage DSC/turn off the light. It's my understanding that the system is completely off at that point.

[328 Power 04]

On the later models (2001-02 maybe?) there was a two-stage DSC with the single press still keeping system involved, but allowing more slip before intervening. If you hold the DSC button down for 10 seconds~, the light will stay on and you have to turn the car off and start in to re-engage DSC/turn off the light. It's my understanding that the system is completely off at that point.

Yes, it will be in "Stuck button fault" and completely disabled. Needs a car restart to get it going again.

On E46's holding the DSC button would turn an additional light on the cluster, turning it completely off, but it was reversible by pushing the button.

[z3papa]

Yes, it will be in "Stuck button fault" and completely disabled. Needs a car restart to get it going again.

On E46's holding the DSC button would turn an additional light on the cluster, turning it completely off, but it was reversible by pushing the button.

You can certain re-engage DSC by merely pushing the button. Matt has it correct with one exception as the anti-lock braking still works.

[FishermanIvan]

Mine goes completely off with one push... no holding at all.

[lokijibber]

Does anyone have an official explanation of what happens when the button is pushed briefly?

When hitting the twisties, I have often forgotten to turn it off. Typically I realize it in the first turn or so when I can't accelerate out. I obviously don't have 10+ seconds at that point to hold it, but I'm not sure I've ever noticed it still interfering. Definitely nothing like the OP mentioned.

FYI: 02 DSC system (M Roadster if it matters)

[328 Power 04]

You can certain re-engage DSC by merely pushing the button. Matt has it correct with one exception as the anti-lock braking still works.

Not on the 2000.... there might be some differences here. Hmm.

[Matt Day]

Not on the 2000.... there might be some differences here. Hmm.

There are definitely different systems on the 99-00 DSC used in the Z compared to the later years. Mine appears to be a single stage. Not sure what system the 01-02 M got.

[coolguy147]

There are definitely different systems on the 99-00 DSC used in the Z compared to the later years. Mine appears to be a single stage. Not sure what system the 01-02 M got.

My 99 has ASC.

[ptee]

Thanks guys, I figured there was something going on.

Mine is a 2001 Z3 Coupe...if it matters (which it seems to).

I find it strange that you can't fully defeat it in a normal way, without making the car think the button is stuck...

[MTRD3]

Thanks guys, I figured there was something going on.

Mine is a 2001 Z3 Coupe...if it matters (which it seems to).

I find it strange that you can't fully defeat it in a normal way, without making the car think the button is stuck...

My car is a 2002 Z3 Coupe, and I can't seem to recall ever having this problem. One, normal push, deactivation triggers the light on the dash and the DSC completely off. Will do some testing in the spring when the car comes out of hibernation... for research purposes of course

[Cheshire2002]

On the 2001 and 2002 Z3 (not sure if the M works the same way) pressing the button once momentarily will light the DSC light will allow the wheels to slip under power in a strait line. If the wheels begin to slip under power in a turn the system will intervene. If you press and hold the DSC button until the yellow brake light also illuminates the DSC system will be completely disabled. The ABS system will continue to function regardless of DSC state.

[Bcar]

my '01 MC one button push and it allows all the tailout fun the roads allow. I havent tried it yet on the MC, but on my '01 E46 M3 if you got into the ABS the DSC would kick back on while the ABS was active, CBC corner-brake-control I think it was called, not sure if the MC has this or not. It could be turned off 100% on the M3 by holding it for ~10 seconds.

[ptee]

On the 2001 and 2002 Z3 (not sure if the M works the same way) pressing the button once momentarily will light the DSC light will allow the wheels to slip under power in a strait line. If the wheels begin to slip under power in a turn the system will intervene. If you press and hold the DSC button until the yellow brake light also illuminates the DSC system will be completely disabled. The ABS system will continue to function regardless of DSC state.

Just confirmed this on my drive into work this morning. My brake light is green though. Thanks!

Interesting that the "Brake" light comes on...why is that? When "regular" DSC is engaged (one push), do the brakes limit the slip and throttle when going around a corner?

In searching a little more on the topic, here is all you need to know: http://forums.bimmerforums.com/forum...6#post23712466

[Bear Grylls]

DSC one push and it is completely off. However you can trip the system so you can't turn it back on and trip the abs light if you slip for to long

Haven't figured that one out yet

Sent from my Nexus 4 using BF.com

[fuz9]

Just confirmed this on my drive into work this morning. My brake light is green though. Thanks!

Interesting that the "Brake" light comes on...why is that? When "regular" DSC is engaged (one push), do the brakes limit the slip and throttle when going around a corner?

In searching a little more on the topic, here is all you need to know: http://forums.bimmerforums.com/forum...6#post23712466

I don't think the brakes get involved at all, under low traction situations the DSC cuts throttle response to limit the power hitting the road. I previously had a 1998 Z3M that had NO traction control system. Driving the two cars near the limit is very different, turning off the DSC on the 2000 Z3M feels exactly like driving the '98.

[328 Power 04]

I don't think the brakes get involved at all, under low traction situations the DSC cuts throttle response to limit the power hitting the road. I previously had a 1998 Z3M that had NO traction control system. Driving the two cars near the limit is very different, turning off the DSC on the 2000 Z3M feels exactly like driving the '98.

The S52 engined MZ3's have ASC, which is just a basic throttle that cuts engine power during a sensed slide.

DSC is more advanced; it will individually apply brakes as well (as needed) to correct car's path. It's excellent for hard weather conditions and not so experienced drivers, to avoid the car stepping out. But its a very strict nanny when it comes to wanting to take a turn harder. My 2000 Z3 DSC will still interfere with it "off" by pushing the DSC button; mostly on turns. If you hold it long enough to trigger the stuck button fault, then it stops interfering at all, but ABS will still work.

My S52 M Coupe with ASC is kind of useless if you know how to lay off the gas pedal quickly when the rear steps out.

[lokijibber]

Well I know for a fact my car will allow the tail to step out a bit with just a single push. I don't think I've ever pushed that into a full snap oversteer, but it sounds like the non-M still won't allow the tail to slide even a bit without holding the button for 10+ seconds.

Maybe some donuts are in order to test this out.

[fire2]

I thought I would clear this all up by going to my owners manual.----wrong, it is clear as mud (late model 2002) but basically it says one
push deactivates the cornering brake control (CBC) and the Dynamic Brake Control (DBC) but keeps the automatic differential brake (ADB) activated,
I didn't even know there was an ADB.------ The longer 3 second push then also deactivates the automatic differential brake (ADB) which results in
all of DSC systems being deactivated.

1. One push of the DSC button deactivates the cornering and dynamic brake control.

2. A long push of 3 seconds deactivates all including-the automatic differential control

The DSC function controls all of the above in conjunction with "adjusting engine output" ,
When it has adjusted the engine output for me the engine momentarily cuts out completely--dont know if thats normal?

[JeffyD]

I'm pretty sure the light will engage as soon as the button is released with a quick press, but will turn on without needing to release after a few seconding of pressing it in. So I have a feeling the above is pretty accurate.

I know that I'm not at all aware of what is happening mechanically to tell the difference between a theoretical two-stage deactivation setup. I do know that I normally hold the button until the light comes on, and not just press the button quickly- and I only do this because it makes me feel my shifting is smoother after doing so. Which could be psycho****tic, but who knows. I do know that I'm awful at driving, but whipping the ass out in these things is more fun than not doing so.

This is being recalled from my time in an '02. Do not remember dealing with ASC in the '99 enough to comment there.

[fire2]

The OP only asked about the DSC so the below is what I decipher from my late model owners manual (no ASC with the late model non M)

I thought I would clear this all up by going to my owners manual.----wrong, it is clear as mud (late model 2002) but basically it says one
push deactivates the cornering brake control (CBC) and the Dynamic Brake Control (DBC) but keeps the automatic differential brake (ADB) activated,
I didn't even know there was an ADB.------ The longer 3 second push then also deactivates the automatic differential brake (ADB) which results in
all of DSC systems being deactivated.

1. One push of the DSC button deactivates the cornering and dynamic brake control.

2. A long push of 3 seconds deactivates all including-the automatic differential control

The DSC function controls all of the above in conjunction with "adjusting engine output" ,
When it has adjusted the engine output for me the engine momentarily cuts out completely--dont know if thats normal?

[JeffyD]

I understand. I was supporting your post. I was also saying that I have no idea how it'd work with the other system. It was an additional comment, and not the reason for the post. That explanation makes sense somewhat. I will reread my manual, because that will make a complete difference in how comprehensible the explanation is, since mine was printed using a less Germanic inkjet copier.

[lokijibber]

So, what the he'll is Active Differential Brake (ADB)? I thought these were all mechanical diffs?

I guess I got more reading to do

[JeffyD]

So, what the he'll is Active Differential Brake (ADB)? I thought these were all mechanical diffs? I guess I got more reading to do

It's the computer's way of acting like a virtual differential by controlling, or attempting to, whatever factors are causing the wheel slippage, or traction loss. Usually through computer that's controlling the engine mapping, and/or it's comrade that monitors brake pressure values. We do have mechanical differentials, and they do their job. But this is the computer program BMW includes with DSC, regardless of a individual vehicle option. Just turn it off, anyway. I think the only thing that can't be turned off is ABS.

Just think of it as BMW using computers to keep you safe from the rain by screwing with the engine output. Too bad it's not that great of a program and should be turned off.

[JeffyD]

Oh, and, guys... If your DSC/whatever light does not turn off promptly after pushing the button while the system is disabled, please go get that checked. Working as intended, the light is supposed to turn off, letting you know you're being nannied successfully. If it doesn't turn off with just a button press, yeah, it could just be a malfunctioning indicator, but it could also be a correctly functioning indicator letting you know yo' **** be ****'d.