DSC light on. steering angle sensor error code : no ouput or misconnection?
 

While stationery and immediately after doing some coding, the 4x4 bulb comes on. the error code was something related to SAS not receiving power. The mechanic told me there might be a misconnection in the wiring or the sensor itself is faulty. he tested and find out no wiring problem and concluded that the sas have 2b replaced. I am not convinced.as he told me he cannot reset the error code !!! He tried then the lock to lock calibration and it didn't work. I searched for that fault code involving sas not powered or no output and could not find the related code. I wanted to concentrate my research based on that exact code bcs most thread I've read was not based on a specific DCS error code. Looking for any helpful info

If the SAS is bad, the code may come back immediatley after disconnecting from DIS and if the DIS can't communicate with it, then it's not going to calibrate... But,you may want to try erasing and calibrating several times to be sure... Sometimes it takes several tries for any changes to work, i.e. it took 5 passes to get the suspension calibration to work and it took the dealer 5 passes to get the new transmission coding to work when we had the tramsmission replaced...

And what coding are you talking about? Did you code for a while, draining the battery down? What is your voltage under load. See the link in my signature, go read that, and tell us what your voltage is with lights stereo and AC on.

Thanks sockethead and slickGT1.

sockethead : what do you mean by erasing? u mean resetting code using the scanner? I also red that you may need to drive the car in a straight line for a few km,after calibration. is that right?

slickGT1 : The battery voltage with low beam stereo & Ac on is between 13.7 & 13.4. coding done for 10-15min to reset passenger door airbag due to passenger window glass regulator replacement in addition to key programming & changing some preferences. The car was stationary, regulator replaced and car get that error while still in place. The mechanic said that replacing the regulator has nothing to do with the sas error, It was just a coincidence !!!. I looked into sas error codes but can't find a code that mention power failure in the sas circuit. mechanic uses Autologic scanner. he said the 4x4 light can't be reset. If he think that sas is faulty then why he tried finally to recalibrate and suspect that the light might goes off after few kilometers ! might the car need alignment? is there minor things I could try myself before taking the car to another mechanic else than trying to calibrate several times?

Yes, resetting clearing , erasing, deleting... each system has it's own name for it.
The scanner he is using is a third party scanner... that may or may not make a difference. I know from experience that some codes cannot be erased using "quick delete" (BMW DIS name for it) You have to go into the module and actually erase within there.
I'm not familiar with the diagnostic system he is using so I can't say if it is capable of doing that.
As far as driving in a straight line , I don't know it that is necessary or not.

If you can find the values, it may be possible to test the voltage or resistance coming out of the sensor

Thanks sockethead . I will go to an experienced car electrician in the coming days & feed you back with results

Second specialized car electronic shop assumed also that sas needs repair (he claims able to repair it from inside rather than replacing it). He reset the code and calibrated the sas to convince me that the light will go ON again and that resetting will not solve the problem. 2m away from the shop and the light get back ON and stayed few km till I arrived home. Next day I drove the car & noticed that the light went off. It was the same for the next 2 days, light still of.

General

In order to function, the DSC system requires the overall steering wheel angle. The overall steering wheel angle is measured by the steering angle sensor. As the software could not be accommodated on the DSC control unit for reasons of processor capacity, a separate control unit with its own fault memory has been developed.
Arrangement in vehicle

The steering angle sensor is mounted on the steering shaft.
Operating principle

The steering-angle sensor has two potentiometers offset by 90°. The steering-wheel angle determined by these two potentiometers covers one full steering-wheel turn; each of these values is repeated after +/- 180°. The steering angle sensor knows this and counts the steering-wheel revolutions accordingly. The overall steering wheel angle is thus made up of the current steering wheel angle together with the number of steering wheel rotations. In order that the overall steering wheel angle is available at any time, uninterrupted detection of all steering wheel movements - even when the vehicle is stationary - is required. In order to achieve this, the steering angle sensor is permanently supplied with power from Terminal 30.This means that steering-wheel movements are also detected with ”ignition off”. The steering angle detected by the potentiometers remains available even after interruptions to the power supply; the number of steering wheel revolutions, however, is not. In order that the steering angle sensor remains functional after power supply interruptions, software that calculates the number of steering wheel rotations on the basis of the speed of rotation of the road wheels (and, on some models, the steering wheel being turned from lock to lock) has been integrated. This process is referred to as initialization or imposition. If imposition does not succeed by the time a speed of approx. 20 km/h is reached from a standing start, the DSC is switched to passive mode, the DSC warning lamp comes on, and a fault is recorded on the DSC control unit. The imposition process is performed whenever the ignition is switched on if the number of steering wheel revolutions is not available. Four-wheel drive vehicles are an exception to this rule: The DSC system is immediately switched to passive mode and a fault entered in the DSC control unit memory if there has been an interruption in the power supply to the steering angle sensor. In contrast with conventional-drive vehicles, the imposition process is then not aborted on reaching a specific road speed, but rather continued until the DSC is receiving correct steering angle data. At that point, the DSC warning light goes out and the DSC is operational again. In both cases, there is no fault recorded on the steering angle sensor. As an additional safety measure, the DSC control unit calculates the steering angle on the basis of the speed of the road wheels and compares it with the information supplied by the steering angle sensor. This plausibility check prevents the vehicle operating on the basis of incorrect calibration. An incorrect zero position can result from incorrect calibration or alteration of the steering geometry as a result of damage or repairs. Another safety factor is precise assignment of sensor to vehicle. During calibration, the VIN number is stored in the EEPROM and then compared with the VIN number received from the instrument cluster whenever the ignition is switched on.
Replacing the steering-angle sensor

After replacing the steering-angle sensor, it must first be coded and then calibrated using the ABS/DSC diagnostic program.
Encoding

In order to perform its internal calculations, the steering angle sensor requires model-specific data which has to be loaded onto it by means of coding.
Calibration

Calibration permanently stores the current steering wheel position as the straight-ahead position in the steering angle sensor EEPROM. Therefore, the front wheels and the steering wheel must be set exactly to the straight-ahead position before calibration. In addition, the vehicle identification number is also read from the instrument cluster and stored permanently in the steering angle sensor EEPROM. On successful completion of calibration, the steering angle sensor fault memory is automatically cleared.

Calibration must always be carried out after the following operations:

• Replacement of the steering-angle sensor
• Replacement of the DSC control unit
• Adjustment work on the steering-angle geometry
• Any work on the steering or front suspension

Voltage supply

The steering angle sensor is permanently supplied with power from Terminal 30 which also has its own fuse. In addition, the steering angle sensor also receives a power supply from Terminal 87 or, depending on model, from Terminal 15. This supply is brought via a different fuse.
Frequency counter:

• When a fault is detected after ”ignition off” the frequency counter is incremented upwards by ”1”. The maximum value is ”31”.
• If the fault no longer occurs during the next trip, the frequency counter is reduced by ”1”. The minimum value is ”0”.

check fuses 12 and 51 in the glove compartment... make sure that they are OK using a multimeter, not just visually...