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my speedometer is not working properly
The inaccurate speedometer of the car may be due to the problem of the speedometer sensor, the internal failure of the sensor, or the sensor is too far away from the induction coil (ring gear) in the gearbox, which may also cause the speedometer to be inaccurate, or the driving computer needs to be adjusted. Same, it is recommended to contact the 4S store to check. Precautions when the speedometer is not allowed to be repaired:
Raise the car with a two-post lift, start the car and put it in gear to accelerate. Use an oscilloscope to observe the pulse signal of the sensor. When the vehicle speed exceeds 80km/h, the pulse signal on the display is intermittent, indicating that the sensor is faulty. The fault can be eliminated after replacing a good reed switch tube, otherwise it is determined that the magnetic ring of the sensor is demagnetized. Due to the weakening of the magnetic field, when the reed switch tube is close to the magnetic field, the internal contacts cannot be attracted. The higher the vehicle speed, the shorter the contact time between the contacts and the magnetic field, and the more serious the loss of pulse signals. After removing the left drive shaft and replacing it with a new magnetic ring, the speedometer will display the driving speed and it will be normal.
(1) Determine whether the sensor or instrument is faulty: Close the sensor connector, turn on the ignition, connect the No. 2 electrode connected to the red wire with a brown background in the device is used the wire with the plug made by the system protrudes from the grounding part of the body divide into a virtual stroke, input a pulse signal wire to the meter. At this time, if the pointer of the speedometer turns. If it moves, it means that the instrument is normal. The fault occurred in the sensor on the reed switch tube or magnetic ring. At this time, if the speed, If the pointer of the meter does not rotate, it means that there is something wrong with the meter or the connection line barrier.
2) Determine whether it is an instrument failure or a line failure:
Remove the instrument panel, do not pull out the plug, test with a multimeter three electrodes on the meter. Turn on the ignition, 26. The power line from No. insurance to the speedometer should be 12V to ground: Measuring with a multimeter electrical break, instrument to sensor connector the resistance of the same pulse signal line should be zero, and the ground pole pair ground resistance should be zero. If the actual measured value is the same as the above three If the values are inconsistent, the open circuit in the line should be ruled out. Fault. If the line under test is not faulty, state the speed If there is a problem with the meter, it should be repaired or replaced as appropriate.
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