General steps for automatic transmission troubleshooting

Diagnostic process of automatic transmission: first of all, we must be familiar with the structure and working principle of automatic transmission, and then the disassembly and assembly of automatic transmission, which can generally include the disassembly and assembly of the front and rear housings, oil pumps, transmission mechanisms, oil pans and valve bodies of automatic transmissions.

The key to an automatic transmission torque converter overhaul is cleaning and finding. Since the shell is basically a welded monolithic organ, it cannot be divided, and there are no parts that mesh with each other, so there will be no hindrance in application.

Secondly, as a key component of the automatic automatic transmission, once the oil pump causes a blockage, it will affect the hydraulic establishment of the entire electronic automatic transmission, rather than a certain gear working alone. In general, the relationship between low-grade and high-end is large, but small.

Generally speaking, the blockage of the oil pump will cause the car in forward and reverse gears to be slower than moving, forward and reverse gears cannot be started, automatic transmission slippage, automatic transmission shift shock, noise, etc. Therefore, the detection of the oil pump plays an important role in the maintenance of the automatic transmission.

The maintenance of clutches, brakes, and planetary gears is the most important thing in automatic transmission maintenance. After removing the brakes, we need to check that the rollers, pistons, and friction plates are in good condition, whether there are cracks or ablations, and whether the planetary gears are in good condition. After dismantling, cleaning and troubleshooting, we should carry out installation and configuration work at the same time.

Because the production and processing accuracy and installation and configuration accuracy of automatic transmissions are basically very high, the installation and configuration should strictly follow the sequence and requirements. @2019

The routine inspection of automatic transmission mainly refers to the analysis of the cause of failure according to the surface phenomenon of automatic transmission reflected by users by seeing, listening, touching, smelling, etc. Routine inspection is an indispensable step in the repair process of an automatic transmission and is the basic inspection before the professional testing of an automatic transmission. Without these routine checks, the latter test could directly cause more damage to the transmission.

Examine. 1) There are many models and manufacturers of automatic transmissions that identify models. There may be several different combinations of engines and transmissions of the same model, and the performance and structural parameters of different combinations of transmissions may be different.

Therefore, first of all, you need to understand the model, production year, automatic transmission model and other information after contacting the vehicle, which is conducive to later fault diagnosis. The identification of the transmission can be confirmed by the nameplate, as shown in Figure 5-1.

2) Visual inspection: Look at the external condition of the automatic transmission when parking. Check whether the automatic transmission is leaking, whether the oil pan is deformed, whether the transmission suspension rubber sleeve is damaged, whether the output shaft of the automatic transmission is loose or disconnected, whether the bending bundle next to the line of the automatic transmission is broken (rubbing the tomato suffocation), whether the wiring is loose, whether the grounding between the automatic transmission and the body is firm, whether the oil pipe of the automatic transmission through the radiator is bent or squeezed, whether the radiator of the water tank is dirty, and whether the shift handle is bent and deformed.

In the car, check whether the throttle cable or lever of the automatic transmission is too loose or too tight (full hydraulic is an automatic transmission), whether the adjustment screw of the throttle position sensor is loose (electronic automatic transmission), and whether the wire connector is not firmly plugged in. These inspections must be careful, because there are many faults that are late and difficult to upgrade, which are caused by these simple reasons. When checking the throttle cable, you should turn the throttle with your hand while looking to see if the throttle cable can return to its original position.

Sometimes there are burrs or breaks in the middle of the cable, which will affect the return of the throttle and thus the upper and lower gears of the automatic transmission.

3) Listening is to make full use of the human ear to judge the location of abnormal noise, distinguish the fault of the transmission or engine, and analyze the possible causes. In this process, we can make full use of some tools and equipment, such as long screwdrivers, special stethoscopes, endoscopes and other instruments and tools to make the diagnosis more accurate.

If the car cannot be driven, check the fluid level of the automatic transmission, the oil pressure of the main oil circuit, check whether the oil inlet filter of the oil pump is blocked, etc.

Common faults of automatic transmissions include: the car cannot drive, automatic transmission skidding, shift shock, too late upshift, unable to upshift, frequent gear jumping, inability to force downshift, engine stall after shifting, no overdrive, no forward gear, no locking, no reverse gear, automatic transmission abnormal noise. There are many reasons for the failure of automatic transmissions, and it is necessary to analyze them carefully when diagnosing them, and they must not be blindly repaired.

Automatic Transmission Slip Diagnostics: Ensure that the automatic transmission oil level meets the requirements. If there are large bubbles in the oil of the automatic transmission, it is because the oil pressure and oil temperature are too high, so stop the transmission to cool down or disassemble it when driving.

Check the clutch, brake pads and brake bands for wear. If the wear is severe, deformed or burned, it should be repaired or replaced in time. Check the one-way clutch for slippage.

If slipping, disassemble and inspect the rollers or inner and outer ring gears. Check the sealing ring of the clutch or brake piston, and replace the sealing ring if there is any oil leakage. Shift Diagnostics:

Start by checking 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 it if it doesn't fit. Check the oil pressure of the main oil circuit.

If the pressure in the main oil circuit is too high or the hydraulic system is not working properly, disassemble the regulator for repair. Check whether the regulating parts of the automatic transmission are suitable, whether the control solenoid valve, shift actuator and electronic control system are damaged by the rollers, open circuits are large or short circuits, and should be disassembled in time if so.

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The common faults of automatic transmissions are as follows:1Oil Leak:

There is oil oozing from the gearbox or oil pan. One reason is the aging of the seal, the poor seal. Another reason is that the shell has trachoma, which is caused by poor manufacturing processes.

2.Engine stall gear: D or R gear is a god to take the engine off may be a damage to the lock-out solenoid valve or a lock-up control valve hairpin.

3.Locking: The improper input and output signals of the gearbox are caused by poor components or circuits.

Sometimes there is a communication problem between the gearbox computer and other system computers. 4.No response to the file:

Release the brake after attaching D or R gear, and the vehicle will not move. This is usually caused by damage to the input shaft or reverse clutch, or damage to the DR brake. 5.

During driving, the impact and rush of the vehicle's gear shift are also common faults in automatic transmissions. It may be because the transmission oil is too dirty, causing the valve body to get stuck. 6.

This phenomenon is mostly caused by the burning of clutch plates. 7.Water ingress into the gearbox due to external causes, causing the gearbox to work abnormally.

This may be due to oil in the tank, or water entering through the gearbox's ventilation cap. 8.Abnormal noise:

When the vehicle is moving, there is an abnormal sound in the gearbox position. This phenomenon is mostly caused by worn parts or improper installation of the gearbox. The above is a common fault analysis and failure analysis of automatic transmissions.