Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
The system is designed so voltage will disappear if a fault is detected with the sensor circuit.
Even with a new sensor, if the signal is not there or not right, the EBCM will set a code. The most probable cause of this issue is something to do with the encoder ring; could be dirt, debris or it could be cracked or broken acting as insulation. The key here is to use a scope or very fast multimeter to verify the signal is indeed being generated - when the magnetic encoder ring rotates and passes by the wheel speed sensor head; it generates a sine wave in the wheel speed sensor. The wheel speed sensor converts this analog signal to a digital square wave, and typical digital signal values switch between 7mA (Low) and 14mA (High) DC current. If the signal is verified as being generated at the sensor, the next step is to check the wiring from the sensor to the EBCM. However if the signal is verified going all the way to the EBCM, if the code resets, then the fault lies with the EBCM itself.