How to Test the Crankshaft Position Sensor?
2 Answers
If the crankshaft position sensor is damaged, the rotation angle of the crankshaft cannot be determined. The engine control unit (ECU) will not receive signals from the crankshaft position sensor, and to protect the engine, it will not ignite or inject fuel. The symptoms exhibited by the car include no high-voltage spark, no fuel injection, and failure to start. The most obvious sign is the illumination of the engine warning light on the dashboard. The methods to test the crankshaft position sensor are as follows: 1. You can determine its condition by measuring the voltage. Turn on the ignition switch and measure the voltage between the two signal wires and ground; it should be 1.4V. This is the preset voltage on the signal wires by the engine control unit. 2. When cranking the starter, measure the signal voltage of the crankshaft position sensor; it should be close to 1.6V. 3. If there is an open or short circuit inside the sensor, in the signal wiring, or within the engine control unit, the ECU will be unable to receive the crankshaft position signal, and the engine will fail to start.
Over the years of running my auto repair shop, I've found three most common methods to check the crankshaft position sensor: First, start the engine and check the warning lights - a yellow light on the dashboard means trouble; Second, plug a diagnostic scanner into the OBD port to read trouble codes, codes like P0335 usually indicate sensor issues; Third, directly unplug the sensor connector and measure resistance - normal range should be between 500-1000 ohms. During actual operation, remember to clean the sensor head as oil and metal debris can affect signals. Last time I encountered a Passat idling as shaky as dancing, only to find a tiny metal shard stuck in the sensor gap. Remember to align the installation angle when reinstalling - any positional deviation exceeding 3mm will affect performance.
