A zongshen Appriya 300 could not be started. After receiving the car, I tried to start it, and found that the engine speed on the instrument was instantly displayed (about 300 RPM) and returned to zero. No matter how long the motor was running, it only showed the speed in the first 1-2 seconds.

Check the crankshaft position sensor signal first. The pit began to drop: following the engine magneto out of the line, I found that the cable connector was in the pedal, and it was impossible to measure the signal without disconnecting the pedal. Did not tear down this car, tear down pedal to spend 1 hour, afraid to tear down to somebody else is broken, fumble slowly tear down.

I'm done. I see the connector. I know the three output lines of the three-phase generator are fine. Put it aside. All that's left is a bunch of couplings that must be crankshaft position sensors.

Look at the wire harness, the crankshaft position sensor should be 3 lines, with experience estimate, 3 lines must be Hall type (jump so unhesitatingly), thought, find the power supply and ground, and then find the signal line results.

MSC super test lamp clamp battery negative, probe by wire test, damn! Not a bright one! Unplug the wiring harness end, found an orange line can light up the test lamp, multimeter measurement and confirmation, found battery voltage, thought hey hey, 12V hall power found.

Insert the plug again to test the signal, the probe into the orange line dead/alive point does not light test. Thought this is 12V power supply virtual connection? Or did the Hall sensor short-circuit and lower the voltage?

Disconnect the plug, use 3W power test lamp one end is connected to battery negative, the other end is connected to the orange wire cable end, the lamp can light up, but the luminosity is very weak, feel some strange, thinking how much electricity hall sensor can use ah? It should be enough! Rectify the fault of the virtual link.

But how do you measure the hall short-circuit pull voltage? My heart is in a hurry! Take the risk of dragging a wire from the positive end of the battery, leaving only a copper wire in the middle to connect (to act as a fuse), wrapping the other end around the probe and inserting the orange wire. Pop! The copper wire is blown.

Plug style, line color can be matched one by one, continue to look down the line, found the other end of a wire terminal like a start motor dust cap like rubber protection.

Immediately back to the car next to check, this suddenly realized, it is not the oil pressure switch! A white switch wire happens to be connected to the orange wire I tested earlier by a 3P plug. This crankshaft position sensor isn't Hall. It's magnetoelectric.

The next test went well, measuring the resistance of the crankshaft position sensor at 125 ω. Connect the plug, MSC super test lamp clip battery positive and negative, the probe is connected to the crankshaft position sensor output line, hit the motor test lamp flashing, indicating that the sensor is normal.

At this time, the instrument still did not show the speed, because the front has wasted almost 2 hours, also did not have the mind to slowly study, continue to let the owner of the electric start, MY ear close to the oil tank to listen to the pump does not turn. Turn, too. It means there's no problem with the fuel supply.

Check the high voltage circuit again, unplug the high voltage cap, remove the spark plug cover, power up, huh? No fire? Put on a new spark plug and try again. It's all right! Load to the car and then play, a start, instrument speed is also normal display!