The engine speed sensor, also called the crankshaft position sensor, is one of the most important sensors in the EFI engine control system. The function of the engine speed sensor is to detect the engine speed, determine the position of the crankshaft, detect the signal of the top dead center of the piston and the signal of the crankshaft angle, and transmit the detected signal to the ECU for controlling the ignition timing and fuel injection timing. What can happen if the engine speed sensor fails? What are the troubleshooting methods for detecting faults? Let's take a look.

Symptoms：

It is not possible to start the generator or run the generator when the generator rotation sensor fails.

If it is only the crankshaft transmission of the engine, most vehicles cannot start the vehicle, because the PCM does not receive the engine transmission signal, and does not provide fuel injection and high-pressure ignition.

Troubleshooting:

Using a display oscilloscope for waveform detection is straightforward and effective.

The electric control unit of the generator does not receive the speed signal or the received signal is unstable. The possible reasons are:

(1) The distance from the sensor to the gear is too large;

(2) The lead wire of the sensor is short-circuited or disconnected;

(3) The sensor is damaged.

Speed sensor measurement:

Measure the resistance between the two feet of the sensor, the resistance should be between 0.7~1.2kΩ:

(1) If it exceeds the specified resistance range, it means that the sensor is damaged and the speed sensor should be replaced;

(2) If the resistance value is within the specified range, you should continue to check whether there is a short circuit to ground, a short circuit to the positive pole, an open circuit or a short circuit between the wires between the sensor and the engine electronic control unit, and repair the problems found in time. If the problem persists after troubleshooting the wiring, the speed sensor should be replaced.