Measurement Method of Crankshaft Position Sensor?
3 Answers
1. Observe the engine speed displayed on the dashboard. The engine speed signal comes from the crankshaft position sensor. If the sensor has no signal output, the engine tachometer will definitely not move. 2. Use a multimeter for testing. Connect the two probes of the multimeter to any two signal wires of the magnetic crankshaft position sensor. Set the multimeter to the 20V range at idle speed. The higher the measured voltage, the higher the speed. 3. Use an oscilloscope for testing. Adjust the oscilloscope voltage to 14V and the time to 10mS. Start the vehicle to observe the AC signal waveform. 4. Use a diagnostic scanner to read the engine speed data stream.
I often deal with the measurement of this crankshaft position sensor when repairing cars. First, locate the sensor, which is usually installed at the front or side of the engine, connected to the crankshaft. Turn off the engine, disconnect the sensor plug, and use a multimeter set to the resistance mode to measure the two pins. The normal resistance is typically around 500 to 1500 ohms. If the reading is infinite or close to zero, it means the sensor is internally damaged. Then, check the circuit continuity to ensure there are no short circuits or open circuits. I remember one time, a friend's car had difficulty starting. I measured the sensor and found it was fine, but the wires had been chewed through by rats. After fixing it, the car ran smoothly again. If you're doing it yourself, prepare tools like a multimeter, and avoid working on a hot engine to prevent burns. The signal output can also be checked with an oscilloscope to observe the pulse wave, but that requires professional equipment. If you encounter issues, read the OBDII trouble codes—P0335 often indicates a fault with this sensor. Simply replacing the sensor is an option, but it's recommended to troubleshoot first to save money.
As someone who understands engines, I've considered that measuring the crankshaft position sensor requires a multi-angle approach. The sensor type is crucial: for magnetic induction types, you can use a multimeter to check resistance and voltage, and there should be slight fluctuations in AC voltage at engine idle; for Hall-effect types, it's more important to inspect the power and signal lines, with DC voltage variations ideally between 0-5V. A simple method is to connect a diagnostic tool to the OBD port and observe whether the crankshaft speed is stable in the real-time data stream. Without tools, a manual check for physical installation looseness or oil contamination can also be effective. Wiring issues are the most common—corroded connectors or broken wires can interrupt the signal, affecting ignition timing. I also ensure the ground connection is solid; otherwise, readings may be inaccurate. Experience suggests these sensors have a lifespan of about 10 years, and aging often leads to startup failures. For precision, renting an oscilloscope to observe the waveform is advisable—consistent pulse patterns indicate proper function.
