DSC / 4x4 Inactive warning light
 

Can anyone throw any light ( no pun intended ) on my recent issue with the above warning light, It has come on a couple of times recently with the beep and then stayed on for the rest of the journey, but once home and car turned off , next trip out no probs, it has only come on about 6 times in the last 2 months and recently with the snow here in the UK the dsc light has been flashing correctly to tell me the system is working fine,,I have a couple of thoughts is it just a sensor gone bad........does the actual four wheel drive continue to work cos the car is permanent 60/40 split four wheel drive I believe, not just a electronic trickery,,,,,,,strangley this issue has only started since I had some suspension work done,, I had the right rear upper and left rear lower arms replaced at an indi garage,,, is there some sensor or something that needs resetting after replacing suspension parts ????.The strangest thing is that it is irratic and not that frequent which makes me think the system is actualy ok but some sensor is tripping,,I hope so cos I'm sure if ther is a bigger issue we are talking loads of $$$$$$ to fix :(:(:(:(

A common cause for those lights is a failure of one of the four wheel speed sensors. Since the DSC system doesn't know how fast one wheel is turning when the sensor has a fault, you get the warning. There are other sensors and wiring harnesses that can cause the light as well, but that one is likely. The problem you have is there are four of them, and you don't know which one it would be (or if it even is a wheel speed sensor for sure). It could also be the steering angle sensor. Best thing is to get the codes read, and save yourself some time troubleshooting it.

Your AWD system would continue to work if you had a non x-drive model, 2003 or prior. Since you list a 2005 model in your signature, that means you don't have a permanent 38/62 torque split front/rear, yours is variable. And that means that if you have a fault on a wheel speed sensor, you won't necessarily have AWD any longer.

A wheel speed sensor isn't loads of $$ to fix, compared to other problems.

thanx, i have a OBD2 code reader , would that flag up the codes I need or are we talking a special BMW only peice of kit. Are the sensors something that can be a DIY fix or must it be a garage, are they plug and play replacement parts..

Worth a try with your code reader, I don't know if it will see the codes or not.

The sensors can be replaced as a DIY. It is comparable to front brake pads in terms of complexity. If you have done brake pads, you can do this.

If you get a location (ie RF), you can swap the sensors left and right to see if you get a code on the LF now, proving that it is the sensor and not the wiring harness. Or, if you do get a code for a specific sensor and you are feeling flush, just go buy a new one (because swapping them around is sort of a hassle).

thanx again, one other thing, my steering wheel is not running straight , hasnt for some time but the car runs true and brake in a straight line, so the steering wheel sensor might also be adding to this. Is there a reason that the system seems to work irraticaly, as i mentioned earlier, i was driving on snow a couple of days ago and the DSC light was flashing as the wheels were slipping indicating all was well, can the system fail and then reset itself and be fully operational untill the next time the warning light comes on and stays on .are the sensors a type of plug and go item, no need for resetting or coding.

Electrical components can be erratic as they fail, they can cause intermittent faults. Turning the vehicle off and then back on can reset some of those faults.

Wheel speed sensors don't need coding. Not sure about the steering angle sensor, I think you can reset it just by turning the steering from lock to lock, there is a procedure here somewhere. If it is the DSC or ABS controller, that does need coding to the vehicle. It also costs $$.

Your OBD reader may or may not give you anything useful in terms of diagnostics. If it doesn't, recommend you get a dealer or someone with a GT1 tester to figure out what it is before just starting to replace components.

This is not correct. My AWD does not work when abs dsc and brake lights are lit. I have a 2001 mod.

I have the same issues, more or less, as you have. And this is the second time in about a year. The first time it started with the lights coming on every once in a while. After a while they would come on every time I drove after a short distance and eventually I lost speedo and trip and stuff too. It was the rear left abs sensor.

This time I have replaced control arm and my steering wheel is offset. Front wheels need alignment. In this case I believe the reason for the lamps to be lit are due to steering angle sensor needs calibration along with a wheel alignment. The dealer agrees with my conclusion. Steering angle ssensor calibration is part of wheel alignment procedure, but not all workshops are able to perform it. They have to have the BMW software to do it. My lamps light up after a couple of miles of driving and I loose awd, abs and dsc. Not an ideal situation as I live in Norway and there is plenty of snow here..

In your case it is hard to isolate the fault. I agree with the above poster that it would be natural to suspect one of the abs sensors at the wheels. You can test them with a multimeter from the abs module, or you could have the faults read at the dealer. I have posted the pinout for the Bosch 5.7 module if that's the one in your car.

thanx for the replies,,just wanted to check the car is still safe to drive????, ie nothing mechanical will be damaged by continuing to drive the car if the light has come on while driving. I will not be able to get the car to a garage before xmas now.

Nothing will be further damaged, but traction will not be as if everything was working, so take it easy.

I agree to the extent that a fault with the DSC controller, or ABS module, could interfere with operation of the vehicle.

However, with a pre x-drive model the torque split in the transfer case is fixed. You will still have mechanical drive. With an x-drive model, a simple fault can cause the torque to all be directed to one axle via the actuator motor on the transfer case.