How to Check the Camshaft Position Sensor?
2 Answers
When the camshaft position sensor fails and the signal is interrupted, a diagnostic tool can be used to detect the fault information, thereby indicating a camshaft position sensor failure. There are two detection methods: 1. Detection of the sensor power supply voltage: Turn off the ignition switch, unplug the sensor wire connector, and connect the positive and negative probes of a multimeter to terminals 1 and 3, respectively. When the ignition switch is turned on, the voltage should be above 4.5V. If the voltage is zero, it indicates a break or short circuit in the wiring harness, or an ECU fault. After turning off the ignition switch, continue to check for any breaks or short circuits in the wiring. 2. Detection of wire resistance: Use the multimeter's resistance function to check the resistance between terminal 1 of the sensor and terminal 62 of the ECU, terminal 2 of the sensor and terminal 76 of the ECU, and terminal 3 of the sensor and terminal 67 of the ECU. The resistance between each wire should not exceed 1.5 ohms. If the resistance is too high or infinite, it indicates poor contact or a broken wire in the wiring harness, which should be repaired or replaced.
As an automotive enthusiast, I've personally repaired many cars, and checking the camshaft position sensor is quite a common task. First, it's essential to understand its function: it informs the engine about the camshaft's position, ensuring proper ignition and fuel injection. If the sensor fails, the car may not start or run weakly. The first step in checking is a visual inspection of the sensor and wiring harness for any damage, corrosion, or looseness, while also cleaning off any accumulated dust. Next, use an OBD-II scanner to connect to the car's computer and read fault codes, such as P0340, which indicates a sensor malfunction. If you don't have the equipment, you can borrow or buy one. Then, use a multimeter to measure voltage: unplug the sensor connector, turn on the ignition, and check if the reference voltage and grounding are normal; afterward, measure the signal voltage, which should change when the engine starts. If the resistance is abnormal and exceeds the specified value, such as around 2k ohms, it needs replacement. Remember, safety first—wear gloves and disconnect power to avoid short circuits and personal injury. Engaging in such DIY activities regularly can save a lot on repair costs and is quite rewarding.