Unknown signal to measure. Is it analog or digital?
If high frequency signal at 75% duty cycle our meter averages the voltage to read 12 volts X 75% = 9 volts
If 12 volts X 50% = 6 volts averaged by meter on DC mode.
If a digital signal stays at 50% duty cycle with frequency changing the meter shows fixed voltage reading. You are thinking sensor never changes.
Oscilloscope can be better than voltage, frequency, and duty cycle on meter for multiple readings.
