How to measure the quality of automotive sensors using a multimeter
The measurement method of crankshaft position sensor needs to refer to the circuit diagram to determine whether active or passive sensors are used. There are two types of sensors in China, one is Hall sensor and the other is electromagnetic sensor. The Hall sensor has three wires, which are 5V power supply, signal, and ground. The measurement method is to use the red probe of a multimeter to measure the signal at the DC voltage level, and the black probe is directly connected to the negative pole! Here I want to explain to you how to measure signals. The sensor is in the car, do not disassemble it, and do not unplug the plug. Use a thin steel wire to insert it behind the plug for measurement!
After connecting the wires, use a wrench to turn the crankshaft pulley and slowly turn it. If the crankshaft position sensor is good, you will find that the voltage on the multimeter will display 0 degrees and 5 volts. Do not rotate too fast yourself. If not, it is a malfunction. The second type is the magneto electric crankshaft position sensor, which has a relatively simple measurement method. Simply unplug the plug and there are two pins inside. Use a multimeter to measure the AC voltage range, with both red and black probes connected to these two pins. Then connect the wires and start the engine. When the engine crankshaft does not rotate, there is no voltage. When starting the engine, you can see a voltage of more than ten volts, which may indicate a higher voltage.
The camshaft position sensor is Hall sensor, and the measurement method is the same as the Hall crankshaft sensor above. It is also connected to the wire, and I slowly turn the crankshaft with a wrench to see if there is any voltage change. This requires turning on the ignition switch.
The intake temperature sensor is now integrated into the air flow meter or manifold pressure sensor in all models.
Its measurement method is also relatively simple. First, look for the circuit diagram and find out which two pins of the intake temperature sensor are. The intake temperature sensor is usually a resistor that changes with temperature. Use a multimeter to measure the resistance and connect the black and red probes to find the two pins. This sensor needs to be heated with a hair dryer. Check if the resistance size has changed. If it does not change, it indicates a fault.
The measurement method for the 3-manifold pressure sensor also needs to refer to the circuit diagram. Look at which is a 5-volt power supply, which is a signal, and which is a ground connection. The side measurement method is to remove the intake pressure sensor from the intake manifold, do not unplug the plug, use a thin steel wire to insert it back, and lead out the signal. Use a multimeter to measure the DC voltage range, with the red probe connected to the signal and the black probe connected to the ground, preferably the negative terminal of the battery! Connect a vacuum cleaner to the interface of the intake pressure sensor and evacuate. It can be seen that the voltage is changing and remains the same as a fault
