ASC won’t work?

[jesset328i]

I drive a 1997 328i that I picked up a few months ago and starting a few weeks ago the ASC light would come on randomly and I would have no traction and I wouldn’t be able to turn it back off. Usually, I would turn the car on and off again and it would go away for a few days/weeks. Starting last week on my way to school it’s been turning on every time I drive me car, sometimes it takes a few minutes and sometimes it happens right away. I live in Winnipeg and we get really bad winters and I drive a lot. I have no traction at all and I’m sliding everywhere. Does anyone know how to fix this? It’s getting to be really sketchy driving around.

[Twistytee]

Welcome to Bfc.

When I had similar symptoms it turned out to be a broken bowden cable on the asc actuator. I replaced the cable and it cured my problem. If the cable is loose it can also result in the intermittent light which is reset when you turn off the car but tripped during a system check. Is your abs light also on? The systems work together so a bad wheel sensor can trip the asc light. Also, not to burst your bubble but the traction control in these cars is pretty rudimentary. It cuts power to the throttle to try to help reduce wheel spin but it doesn't actively control four corner braking. Better than no help but you'll still slide in winter conditions without good snow tires.

[jesset328i]

I’ll take a look when I’m off school for that cable. My abs works fine and the light isn’t on. I know how the traction control works on these cars and I still slide around corners if I’m not careful but when I’m taking off from a red light or something like that I just slide. I’m on all season tires right now but I don’t plan on getting winters because this is the only winter I’ll be driving this car so it’s not worth it to me. Thanks for the reply

[JDStrickland]

The ASC light blinks when the system is doing whatever it does, if the light comes on steady then the system is not reliable - it might not provide the service it is intended to provide.

Do you have tires that are all the same diameter? Mismatched tire sizes will confuse the system and this can cause it to work when you may not want it to, or not work when it should. ASC compares the the speed of the front and rear tires, if the rear tires are turning remarkably faster than the front, then ASC kicks in and cuts the throttle and applies the brake to the offending rear tire. When this is happening, the ASC light should be blinking. When the ASC light is on stead, then the rear tires should simply spin freely if there is insufficient traction.

You are not clear that the rear tires are spinning on the ice, or if the throttle is not doing what you would expect. If you are applying throttle and getting nothing, then the ASC is cutting it because it thinks a tire is spinning freely and the ASC light will be blinking in this condition. If you are applying throttle and the tires break free, then do not apply throttle with so much enthusiasm. The ASC light will be on steady in this condition, telling you that rear wheel spin will not be controlled reliably.

If the light is blinking, the system is working. If the light is on steady then the inputs to the controller are nonsensical and system integrity is unreliable. This is usually the result of mismatched tire sizes. What are your tires sizes?

[jesset328i]

I know the light blinks when the system works, the problem has only really started the past few weeks and it’s gotten to be an everyday thing starting around last week. Even when I apply light throttle my rear tires spin, the roads where I live are pure ice right now. I think my tires are 225/45/r16 but I could be wrong, I can’t remember the size of my sidewall but I know all four tires are the same size

[JDStrickland]

I know the light blinks when the system works, the problem has only really started the past few weeks and it’s gotten to be an everyday thing starting around last week. Even when I apply light throttle my rear tires spin, the roads where I live are pure ice right now. I think my tires are 225/45/r16 but I could be wrong, I can’t remember the size of my sidewall but I know all four tires are the same size

The size doesn't matter if all of them are the same. With the 16s, you should have a 225/50, by the way. 225 describes the tread width, 50 (or 45) describes the sidewall height as a percentage of the tread width. Of course, 16 describes the diameter of the rim.

So, is the ASC light on steady? If yes, then your car is telling you that the system performance is not reliable. You are in the Great White North, (enjoying white privilege) so there's no telling what the problem might be. You are driving in conditions that might exceed the capability of the car to compensate for.

[Eric93se]

Clean all of your ABS sensors, be careful because you can break them when it's crazy cold out. But there is just a small allen bolt holding them in and then there is a slight interference fit, so some wiggling and pulling is necessary. Clean the sensor tips with a rag and WD40.

[shogun]

ABS, ASC, AND ASC+T MALFUNCTION
MODELS AFFECTED: All models equipped with ABS,ASC OR ASC+T
FAULT: Any of the ABS ASC and ASC+T systems inoperative, intermittently inoperative, or illuminating the warning lamp.
CAUSE: All BMW'S with slip control systems use 4 wheel speed sensors which monitor each wheels speed of rotation with a high accuracy. The system control unit uses this information to calculate a vehicle speed. In this way it detects wheel speed variation. If the inputs vary from each other by a certain amount, the control unit is not able to do the calculation reliably (plausibility fault) and takes its self off-line as a safety precaution(fail-safe).This can be because the wheels and tires are non-approved parts and therefore do not agree with the system.
SOLUTION: Make sure the vehicle is fitted with BMW approved wheels and tires. Then do further diagnostic testing to check if fault is resolved.

http://www.bba-reman.com/us/content/...w_abs_problems

[bcurrie]

Just the past few days I started having a similar problem, my abs and traction light will randomly come on and stay on for a while. Went out for a drive tonight and when I first stated driving, no lights then about 20mins later it came on and stayed on. Well see in the morning if its on or not, I know its probably just the sensor but I dont understand why it randomly goes on or off.

[Nanniepoo]

And here I am frequently turning the system off so I can have some fun :p

[gdavid]

I suspect you have two separate issues going on. This was the case in my car, both were pretty typical failures and easy fixes.

1- A poor connection or fault in the ASC system, causing the light to come on and not go off.
2- Bad rear end alignment that is causing bad traction. Worn or broken trailing arm bushings will throw off your rear toe in, so you rear wheels aren't parallel to each other.

On my car I had a bad solder joint inside the brake pedal position sensor that allowed it to work properly when the car was cold and resistance was low but lost the connection as the circuit heated up and resistance increases. Apparently it is a common problem as someone wrote up a DIY thread to disassemble and fix the sensor. The broken solder joint was clearly evident upon inspection and it was an easy fix. I'm not saying yours is necessarily the same problem, but I suspect somewhere in the system you have a bad electrical connection.

On the alignment front, the trailing arm bushings (TAB's) are a maintenance item that is due for all of these cars based on age alone, if yours have not been replaced or were replaced without a proper alignment, it could very easily explain a terrible traction issue. There are several threads on here about TAB's, they aren't the easiest to replace but it really isn't too bad of a job and many novice's have tackled them.

[jesset328i]

It’s been a few days and I haven’t tried to fix it at all but the problem stopped. When it was going off constantly, we were in the middle of a crazy cold snap, like -30° and colder every day. Since the beginning of this week it’s warmed up quite a bit and the problem fixed itself... the extreme cold must have messed something up