The instrument voltage and motor display are normal, but the speed display is abnormal. The following Electric Bike Manufacturer introduces why this happens:
1. Reasons for failure: ①The instrument is damaged. ②The speed signal line (black/white) is short-circuited. ③The controller has no speed display.

2. Troubleshooting: Brushed and 48V brushless: Use a multimeter to detect the speed signal line and the positive pole of the power supply (48V brushless detection speed signal and negative) with the motor running speed, the voltage changes from low to high (36V Models have 0~36V changes, 48V with brushes have 0~48V changes, 48V without brushes have 0~25V changes). If there is no change, check whether the speed signal line is connected properly? Is there a short circuit? If the voltage changes normally, it is a failure of the instrument. If the speed display is low, use a screwdriver to adjust the speed adjustment potentiometer on the instrument panel to normal. 36V brushless: first check whether there is a short circuit between the instrument panel and the controller speed line (black/white) connection line. If it is normal, you can connect the controller speed signal line and the motor Hall line (thin yellow, green, blue) any phase line. If the speed is normal, the controller is damaged, if there is still no display, the small meter is damaged.

Through the above introduction, Electric Motorbike With Brushless Motor  Manufacturers hopes that you can simply refer to the content of this article in future use.