What are the steps to test the crankshaft position sensor?
2 Answers
Testing method for the crankshaft position sensor is as follows: Turn on the ignition switch and measure the voltage between the two signal wires and ground, which should be 1.4V. This is the preset voltage on the signal wires by the engine control unit. When starting the engine, the signal voltage of the crankshaft position sensor should be close to 1.6V. If there is an open or short circuit inside the sensor, signal wiring, or engine control unit, the computer will be unable to receive the crankshaft position signal, and the engine will fail to start. Additional Information: If the crankshaft position sensor is damaged, the rotation angle of the crankshaft cannot be determined, and the engine computer will not receive the signal from the crankshaft position sensor. To protect the engine, it will not ignite or inject fuel. The symptoms exhibited by the car will include no high-voltage electricity, no fuel injection, and failure to start. The most obvious sign is the illumination of the engine fault light on the dashboard.
As someone who frequently deals with engine issues, I believe checking the crankshaft position sensor requires a systematic approach. First, I turn off the engine and disconnect the negative battery terminal to prevent short circuits. Then, I visually inspect the sensor for oil stains, cracks, or damaged connectors, ensuring the wiring connections are secure. Next, I connect an OBD-II scanner to the vehicle's port to read fault codes. If codes like P0335 related to the sensor appear, it's a clue. I then set a multimeter to the resistance mode and measure the resistance across the sensor terminals to verify if it matches the manufacturer's specifications (typically ranging from a few hundred to a thousand ohms). Any deviation indicates a problem. After that, I start the car but only let the engine idle, using the multimeter in voltage mode to monitor the output signal voltage for stability. Normally, it should fluctuate between 0.5V and 5V. If the readings are unstable, I use an oscilloscope to check if the waveform is regular—irregular waveforms suggest a fault. The entire process requires attention to detail because the sensor controls ignition timing. If it fails, the car may shake or fail to start. Therefore, after testing, I clean any surrounding oil stains to avoid affecting future readings. Regular inspections like this can prevent costly major repairs.
