Common automatic transmission failures include: car can't drive, automatic transmission slip, shift shock, upshift too late, inability to upshift, frequent skipping, inability to kick down, engine stall after shifting, no overdrive, no forward gear , No lock-up, no reverse gear, abnormal noise of automatic transmission. There are many reasons for the failure of the automatic transmission, which must be carefully analyzed when diagnosing, and must not be repaired blindly.
Trouble Diagnosis of Vehicles Unable to Drive (1) Fault Phenomenon
Regardless of whether the joystick is in reverse or forward gear, the car cannot be driven; the car can only travel for a short distance after starting, and cannot be driven after the car is warmed up. (2) Causes of failure ① The connecting rod or zipper between the shift control handle and the manual valve slide arm is loose, so that the manual slide valve is kept in the neutral or parking position. ②The oil pan of the automatic transmission is damaged, and the oil leakage of the automatic transmission makes the liquid level too low. ③The oil pump inlet filter is blocked or the oil pump is damaged. ④The main oil circuit is seriously damaged. (3) Troubleshooting and troubleshooting When the car cannot be driven, first check whether the connecting rod or zipper between the shift handle and the manual valve slide arm is loose and the position is appropriate. Check the liquid level of the automatic transmission. If it is too low, find the cause and location of the oil leakage, and repair and replenish the oil in time. Check the oil pressure of the main oil circuit. If the oil pressure is too low, further check the input shaft, output shaft and planetary gear mechanism, and repair or replace the damaged parts. Check whether the oil pump inlet filter is blocked, and clean or replace it if necessary. Check whether the oil pump is damaged. If the oil pump is damaged, it should be repaired or replaced.
Automatic transmission slip fault (1) fault phenomenon The transmission slips and causes the drive to be weak. When the accelerator pedal is pressed during automatic start, the engine speed rises quickly, but the vehicle speed rises very slowly; when the accelerator is pressed during driving, the vehicle speed cannot increase rapidly with the increase of the engine speed; the car runs normally on a flat road, but cannot go uphill , the engine speed is abnormally high. (2) Reason ① The oil level of the automatic transmission is too low due to oil leakage. ②The oil level of the automatic transmission is too high, and a lot of air bubbles are generated after being vigorously stirred by the planetary gear mechanism during operation. ③The clutch, brake pad, and brake band are worn or even burned. ④The oil pump is worn out or even the main oil circuit leaks, causing the oil supply pressure to be too low. ⑤ One-way clutch slips. ⑥The clutch or brake piston sealing ring is damaged, resulting in oil leakage. (3) Troubleshooting ① Ensure that the oil level of the automatic transmission meets the requirements. ②If there are a lot of air bubbles in the automatic transmission oil, it is because the oil pressure and oil temperature are too high. Stop to cool down or remove the transmission while driving. ③ Check the wear of clutch, brake pad and brake band. If it is seriously worn, deformed or burned, it should be repaired or replaced in time. ④ Check whether the one-way clutch slips. If slipping, remove and inspect rollers or inner and outer ring gears. ⑤ Check the sealing ring of the clutch or brake piston. If there is oil leakage, replace the sealing ring.
The automatic transmission shift shock is too large (1) When there is a fault in the automatic start, when the parking gear or neutral gear is placed in the forward gear or reverse gear, the automatic transmission of the car will not work well, resulting in large shock and vibration; when the car is driving , the automatic transmission has a great influence on the shifting process. (2) Reason ①The idle speed of the engine is too high. ②The throttle cable or throttle position sensor is improperly adjusted, or the main oil circuit pressure regulating solenoid valve is faulty, resulting in the main oil circuit pressure being too high and the hydraulic system working poorly. ③ The transmission and engine rubber pads are worn, the connecting bolts are loose, and the transmission system clearance is too large or loose. ④ The accumulator fails, and the damping buffer oil pressure acting on the back of the accumulator is abnormal. ⑤ The working clearance of the friction elements of the shift actuators such as brakes and clutches is abnormal; the one-way clutch slips or is poorly locked, causing movement interference; the clutch or brake separation time is too long or not completely separated before shifting. ⑥ The shift point of the automatic transmission is incorrect. ⑦The hydraulic solenoid valve does not work. ⑧ The electronic control part is faulty. (3) Troubleshooting First check the idle speed of the automatic transmission, and adjust it if it is too high. Check the throttle cable or throttle position sensor and adjust if not suitable. Check the oil pressure in the main oil circuit. If the main oil circuit pressure is too high or the hydraulic system is not working properly, remove the pressure regulating valve for repair. Check whether the adjustment parts of the automatic transmission are suitable, and whether the control solenoid valve, shift actuator and electronic control system are damaged, open circuit or short circuit, if any, they should be disassembled in time.
Automatic transmission abnormal noise fault (1) fault phenomenon When the car is driving, there is always abnormal noise in the automatic transmission, but it disappears after parking in neutral. (2) Reasons ① The oil pump is excessively worn, and the oil level of the automatic transmission is too high or too low. ②The torque converter lock-up clutch, guide wheel and one-way clutch are damaged. ③ The planetary gear mechanism is faulty. ④ Abnormal sound of shift actuator. (3) The fault diagnosis and elimination of abnormal noise of automatic transmission mainly occurs in mechanical and hydraulic systems. Abnormal noise sources mainly include: fluid noise of gear mechanism, bearing, oil pump, friction plate, main reducer and torque converter. When diagnosing, first locate the abnormal sound source, and then troubleshoot the relevant components. ① First check the oil level of the automatic transmission, if the oil level is too high or too low, it should be adjusted. ② Determine the abnormal noise location. If the front is abnormal, the oil pump, torque converter, lock-up clutch, guide wheel and one-way clutch are faulty and should be disassembled for repair. ③If the rear part is abnormal, it means that the planetary gear mechanism is faulty and should be disassembled and repaired. ④If there is abnormal noise when shifting gears, shift actuator, clutch and brake band, etc. If there is a fault, it should be disassembled for maintenance.
