Crankshaft position sensor is generally installed in front of the crankshaft or rear, and connected to the crankshaft on the signal pulse disk corresponding to the location of the crank angle and its rotation speed. As the engine Sensor crankshaft rotates, the tooth tip of the magnetized signal plate is close to, aligned, away from the sensing end of the sensor, resulting in a change in GMR resistance. The magnetic field changes detected by the GMR element are converted into square waves in the CKP internal signal processing circuit and then input to the ECM as a CKP output signal. When the engine speed increases, the square wave signal frequency also increases; the other hand, the square wave frequency will be reduced. Compared with the Hall sensor, the use of GMR components CKP sensor to improve the stability of the signal, and the signal amplitude is wider.
In the CKP sensor, the square wave voltage signal shape characteristics also according to the shape of the signal board tooth changes, ECM is based on CKP these shape characteristics also determine the crank angle position, and the Suction Control Valve camshaft position sensor signal to determine the engine with the gas Phase.
Crankshaft position sensor failure phenomenon and diagnosis:
When the crankshaft position sensor signal is abnormal, it may cause difficulty in starting, such as failure after starting.
The main causes of crankshaft position sensors include:
1. The sensor is internally damaged.
2. The sensor head is damaged / dirty (metal chips and other easily susceptible objects will be adsorbed on the sensor).
3. Connector or line break / short circuit.
CKP sensor performance measurement methods, mainly visual inspection, resistance measurement fuel metering valve and waveform measurement and other methods.
1. Visual inspection:
(1) Check O-ring for damage.
(2) Check the sensor end and the signal wheel teeth are metal particles and damaged.
(3) check the sensor installation and signal board teeth between the gap is normal, should be about 1mm.
2. Resistance check:
Use a 12V battery (1) to connect its positive terminal to the 'Vin' terminal (2) and the negative terminal to the 'ground' terminal (3) of the sensor. The resistance between the sensor 'Vout' terminal (4) and the battery negative terminal is Temperature Sensor then measured by means of a magnetic substance (5) by means of a resistance meter while maintaining a distance of about 1 mm (0.03 inch) with the CKP sensor.
CKP sensor resistance:
Resistance changes from less than 220Ω (ON) to infinity (OFF), or from infinity (OFF) to less than 220Ω (ON). If the resistance change does not match the requirements below, the CKP sensor should be replaced.
3. Waveform measurement:
Using the oscilloscope to detect the crankshaft position sensor signal terminal voltage waveform, when the engine idling operation, the detection of low frequency square wave signal. When the engine speed increases, the frequency Pressure Sensor gradually increased the waveform.
Maintenance Note: Crankshaft position sensor is more sophisticated, to gently, to avoid falling on the ground and damage the sensor. Be careful when installing, and can not hammer.