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speedometer not working and transmission not shifting
There are four possible reasons for this fault. First, the speed sensor is damaged; Second, the transmission wiring is broken; Third, the grounding is faulty; Fourth, the clip at the connection between the road code meter and the gearbox is loosened. The actual cause of the fault can only be known through troubleshooting.The speedometer is actually composed of two meters, namely speedometer and odometer. The odometer is a digital instrument, which calculates the rotation through the meshing of parts on the valley wheel of the calculator. It mainly obtains the mileage signal from the speed sensor, and can save the data when there is no electricity. There are usually two kinds of performance when the speedometer does not move. One is that the pointer remains stationary at the position of 0, which is usually because the internal circuit is broken or it's a short circuit. One is that the pointer is at the high point and does not move, which is commonly known as the run and burst meter. In this case, it can be adjusted back that's it. If it is found that it does not move at the position of 0 and the mileage number does not move, it indicates that the vehicle speed sensor is faulty or the instrument is faulty it is caused by a circuit fault between the sensor and the.
Troubleshooting
(1) For electronically controlled automatic transmission, fault self diagnosis shall be carried out first. Sensors affecting shift control include throttle position sensor, vehicle speed sensor, etc. Find the cause of the fault according to the displayed fault code.
(2) Readjust the throttle cable or throttle position sensor according to the standard.
(3) Check the speed sensor. Replace if damaged.
(4) Check the signal of the gear switch. In case of any abnormality, it shall be adjusted or replaced.
(5) Measure the governor oil pressure. If the speed of the governor rises, the hydraulic pressure of the governor is still 0 or very low, indicating that the governor is faulty or the governor's oil circuit is seriously leaking. In this regard, the governor should be disassembled and inspected. If the governor valve core is stuck, it shall be disassembled and cleaned, and the valve core and valve hole shall be polished with metallographic sandpaper. If the governor is still stuck after cleaning and polishing, replace the governor.
(6) Check the governor oil circuit with compressed air for leakage. In case of leakage, replace the sealing ring or sealing ring.
(7) If the oil pressure of the governor is normal, remove the valve plate and check each shift valve. If the shift valve has a cassette, take out the valve core, polish it with metallographic sandpaper, clean it and install it. If it cannot be repaired, replace the valve plate.
(8) If there is no fault in the control system, disassemble the automatic transmission, check whether each shift actuator slips, and check whether each clutch, brake oil circuit or piston leaks with compressed air.
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