English 
how to fix a broken speedometer
The common fault of electronic speedometer is that it doesn't work. The reason is that the sensor is broken or the harness, instrument and watch are faulty.Take Audi as an example, the electronic speedometer sensor is located on the left side of the transmission housing.
(1) Disconnect the combination instrument harness connector, which has 26 terminals.
(2) Lift the car, disconnect the harness connector of the sensor, put the transmission in neutral, and turn the left front wheel by hand.
(3) Use a multimeter to measure the resistance between terminals 4 and 10, and the resistance value should vary from 0 to OO. Otherwise, repair the circuit or replace the speed sensor.
Precautions for use and maintenance of electronic speedometer
1) Ensure that the speedometer uses the rated working voltage, and pay attention to the factors that cause the voltage stabilizing circuit in the speedometer to burn out. Especially in winter diesel
The machine cannot be started, and the method of high-voltage forced starting with jumper method is adopted. Some use 36V or even 48V power supply. If the instrument power supply is not newly turned on (unplug the instrument fuse), it is easy to cause the voltage stabilizing circuit in the speedometer to burn out. Such cases have been encountered by Yutong and Jinlong buses.
2) Make sure that the speedometer does not allow rainwater to enter, and the components in the speedometer will be broken down and damaged by water entering one day. Therefore, those who leak the front windshield glass should pay special attention.
3) When replacing the speedometer, in addition to ensuring that its physical dimensions are the same, it is also necessary to determine whether the speed ratio, applicable voltage and applicable speed sensor waveforms are consistent. The general speedometer is pasted with the label of transmission speed ratio and applicable voltage on the back, which should be consistent with the original speedometer, otherwise there will be great error in the speedometer. According to the different shapes of the signals from the dry speed sensor, the selected speedometer should match the speed sensor. The speedometer used in Hongyan car and Jiefang car is the same in physical dimensions, but Hongyan car adopts magnetoelectric speed sensor. Hall type speed sensor is adopted. Although they are both square wave signals, the waveform and amplitude are different, and the two cannot be interchanged. Otherwise, the speedometer will not work.
Get a Quote / Info