How to measure the quality of car sensors with a multimeter
1. To measure the crankshaft position sensor, you need to look at the circuit diagram to determine whether it is active or passive. There are two sensors in China, one is a Hall sensor and the other is an electromagnetic sensor. . The Hall sensor has 3 lines, which are 5V power supply, signal and ground. The measurement method is to use the red test lead at the DC voltage range of a multimeter to measure the signal, and connect the black test lead directly to the negative pole! Here I want to tell you how to measure the signal. The sensor is in the car. Do not disassemble it, and do not pull out the plug. Use a thin steel wire to insert it behind the plug to measure!
After connecting the wires, use a wrench to turn the crankshaft pulley and turn it slowly. If the crankshaft position sensor is good, you will find that the multimeter voltage will display 0 degrees for a while and 5 volts for a while. Do not turn it too fast. Failure if not. The second type is the magnetoelectric crankshaft position sensor. Its measurement method is relatively simple. Just unplug the plug. There are 2 pins inside. Use a multimeter at the AC voltage setting. Connect the red and black test leads to these two pins. Then connect the wires and start the engine. When the engine crankshaft is not rotating, there is no voltage. If you start the engine, you can see a voltage of more than ten volts. It may be higher, which means it is good.
The camshaft position sensor is a Hall sensor and the measurement method for the Hall crankshaft sensor above is the same. It is also connected to the wire. I slowly turn the crankshaft with a wrench to see if there is any voltage change. In this case, the ignition switch needs to be turned on.
Intake air temperature sensor, intake air temperature sensor is now integrated into the air flow meter or manifold pressure sensor.
Its measurement method is also relatively simple. First, look for the circuit diagram and find out which two pins the intake air temperature sensor has. The intake air temperature sensor is generally a resistor, which changes with the temperature. Use the resistance range of a multimeter, black and red. The two pins found by the test lead connection, this sensor needs to be heated with a hair dryer. Check whether the resistance size changes. If it does not change, it means there is a fault.
The measurement method of the manifold pressure sensor also requires looking at the circuit diagram to see which one is powered by 5V, which one is the signal, and which one is the ground iron. The side measurement method is to remove the intake pressure sensor from the intake manifold without unplugging the plug. , use a thin steel wire to plug in the back, lead out the signal, use the DC voltage setting of the multimeter, the red test lead is connected to the signal, and the black test lead is grounded, preferably the negative pole of the battery! Connect a vacuum to the intake pressure sensor interface and evacuate it. You can see that the voltage is changing and it does not turn into a fault.
