P0387 Toyota Crankshaft Position Sensor B Circuit Low Input
– Crankshaft position sensor harness is open or shorted
– Crankshaft position sensor circuit poor electrical connection
– Signal plate may be damage
– Starter motor may be faulty
– Starting system circuit
– Dead or weak battery
– Lack/Loss of Power
– Engine Stall
The Crankshaft position sensor also known as the crank position sensor is an electronic device used in an engine to record the rate at which the crankshaft is spinning. This information is used by the Electronic Control Module (ECM) to control ignition and fuel injection. The sensor system consists of a rotating part, typically a disc, as well as a static part, the actual sensor.
When the engine is running, the high and low parts of the teeth cause the gap with the sensor to change. The changing gap causes the magnetic field near the sensor to change. The change in the magnetic field cause the voltage from the sensor to change.