Test and Measurement Forum

hi, i am having trouble with a mb a170 td in so much as the esp/abs warning lights are on. fault code c1140 open circuit-have carried out tests on feeds and earth and am now faced with a bit of a delema. could be angle sensor or ecu? has anyone scoped an angle sensor before? what settings did you use? what kind of pattern should i see. its a bosch system (esp 1.14)

Unfortunately we do not have any experience of doing this but I would suggest looking for a voltage change or a change in duty cycle based on the steering angle, this would involve probing the output pin of the sensor on the steering. Hope this helps.

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THE PicoScope Automotive Authority
In North America

In the case of BMW and I would assume a Benz to be the same, the sensor is equipped with a processor and is directly linked to the CAN bus to communicate with the (sic BMW DSC III) module.
That is the steering angle is communicated over the CAN bus probably using the SAE J1939-15 or other similar standard
The sensor still utilizes two potentiometers to determine the steering angle and the rate of
steering. These are the raw signals the CAN Bus microprocessor utilizes to create the steering
angle signal for broadcast on the CAN bus.
Thus I would think it would be very hard if not impossible to be able to probe the potentiometers without disassembly and possible destruction of the unit. To prove my view you would need to examine another sensor out of the car to see if access can be gained. Regardless any probing will need to be done at the sensor.