Recently to repair a power star electric tricycle. The owner of the car reported that his horn did not sound and the headlights were not on and off. These were minor problems. What's more, the car often could not charge when it was turning a corner.

Check the car, first open the electric door lock, the meter quantity display is normal; When you press the button, you can hear a slight "click" sound from the speaker, but the speaker does not sound properly. Install a new 48-volt speaker and the sound will return to normal.

Then check the headlights, turn on the headlights switch, the headlights are not on. Try turning the handlebars left and right, found that turning the handlebars to the right, the headlights did not light, the handlebars back or left turn, the headlights can be normal light.

Check the wiring harness of the handlebar faucet. Cut the wire harness open, first check the connection of the ground wire of the loop, no problem is found. Check the power cord from the headlight switch to the headlight again and find nothing wrong.

At this time, the multimeter is used to measure the DC voltage range, the black dial pen is connected to the circuit ground of the whole car wiring harness, and the red dial pen is contacted in turn for measurement.

First test the headlamp plug, found no voltage (pay attention to the multimeter reading, the unit displayed is "mV"); Then move the red pen to the headlight switch plug measurement, the same no voltage; Move the red watch pen to the fire line of the electric lock to measure the voltage is normal (pay attention to the multimeter reading, the unit displayed is "V").

Look carefully at the plug of the headlight switch. There are two power lines, both red/white. One of the voltages is normal, and the other is not.

Go forward to check, in the whole car wiring harness inside to find the connection of the whole car fire line, found a red/white line is broken. Put it back on. This time the headlights are working.

Then road tests found that cars sometimes couldn't get gas with their headlights on. Unplug the rear light and try again all is well.

This indicates that there is a problem with the circuit of the rear light. When the headlight is turned on, current passes through the rear light, and at the same time it flows back to the controller through the brake light. The controller receives the voltage signal of the brake, and then makes the control instruction of "brake power off".