C Klasse ABS and Traction Control Problem

I had something similar happen on my C Klasse. ABS light, traction control going crazy. For me, it was a faulty wheel speed sensor. They send speed info to the ABS module. If one is off, the whole system can get confused. A control unit could also be the problem, but the sensor is cheaper to fix. Have you scanned the car for specific fault codes? That'll pinpoint which sensor is acting up. It could also be a wiring issue to the sensor itself.

You mention a 'wheel speed sensor'. Is this distinct from the speed sensor that interfaces with the transmission, or are they the same? I thought the signal originated from the transmission, influencing both the speedometer and the ABS functionality. I will get the specific fault codes as you suggest.

The wheel speed sensors are at each wheel hub, not directly on the transmission. They use a toothed ring (reluctor ring) and a magnetic sensor to measure the rotational speed of each wheel individually. This data goes to the ABS control module. The transmission does have speed sensors, but they are primarily for the ECM and transmission control. If your speedometer is working fine, the issue is likely with one of the wheel speed sensors or the ABS module itself. With those symptoms and the potential for a faulty control unit, I'd recommend taking it to a trusted workshop for a proper diagnosis. They can use advanced diagnostic tools to isolate the problem.

I appreciate your advice. Following your recommendation, I consulted a technician who confirmed a faulty wheel speed sensor. The replacement fixed the issue. Thank you for sharing your experience; it helped guide the diagnostic process.