ELECTRICAL SYSTEM
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Engine speed sensor
The working principle of the speed sensor is to use the
magnetoelectric eff ect. When the shaft rotates, the signal
wheel is driven to rotate together, and the teeth on the
signal wheel will cut the magnetic line of the sensor. This
change in magnetic flux causes a certain frequency at
both ends of the sensor coil. The output voltage is output
to the electronic controller, and the output signal can
represent the crankshaft speed and position (see A in the
fi gure below).
Technical performance test
The speed sensor outputs a sinusoidal voltage signal,
and the output signal (see 【B】 on the left)
Coil resistance (23 ℃) : 950-20 Ω
Coil inductance (1000HZ) : 450±15 mH
Fault diagnosis
◆ When the engine cannot be started,the remaining
fault points have been eliminated. Use a multimeter
to test whether the coil resistance of the speed
sensor is the resistance required by the technical
performance.
◆ If the resistance value is normal, please use an
oscilloscope to check whether the voltage signal
output by the sensor is as shown in the fi gure (B in
the left fi gure)
!
When the two pins of the sensor are connected
reversely, the fi rst gear signal after the missing gear in
the output voltage signal is negative, which will cause
the engine to be turbulent, idling unstable or unable to
start.
A
B
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