Note: Automatic transmission malfunctions can occur for the following reasons: reduced engine performance, incorrect adjustments, hydraulic system problems, mechanical problems, and processor electrical problems or malfunctions. Diagnosis should begin with the simplest tests: checking the condition and level of the transmission fluid (see chapter 1), as well as checking the correct adjustment of the selector cable (see subsection 3). After this, a test run should be carried out. If the problem is not resolved, further diagnosis should be carried out. If the cause of the malfunction cannot be determined after preliminary diagnosis, provide the vehicle to qualified specialists at a service and repair station. IN section «Determining the causes of malfunctions» A description of the symptoms of problems that occur with an automatic transmission is provided.
Preliminary diagnosis
1. Drive the vehicle until the transmission fluid warms up to normal operating temperature.
2. Check the fluid level as described in Chapter 1:
- A) If the level is below normal, add transmission fluid until the level rises to the normal dipstick level. Make sure there is no fluid leaking from the box.
- b) If the level is higher than normal, drain excess transmission fluid and check for coolant fluid contamination. The presence of coolant in the transmission oil of an automatic transmission indicates a leak in the heat exchanger, the walls of which separate the coolant and transmission fluids (see _ chapter 3).
- With) If foaming of the transmission fluid is noted, drain and refill the transmission, then ensure that there is no coolant in the transmission oil and that the transmission fluid level does not exceed the required level.
3. Make sure that the engine idle speed is normal.
Note: if during the test malfunctions in the operation of the engine are identified, further preliminary diagnostics of the box should be interrupted and problems in the operation of the power unit should be corrected.
4. Inspect and adjust the shift mechanism cable (see subsection 3).
5. Make sure the Park/Neutral position switch is adjusted correctly (PNP) (see subsection 5).
Checking for transmission fluid leaks
6. Transmission fluid leaks can often be detected by visual inspection. Fixing this problem usually involves replacing the oil seal or gasket. If the source of the leak cannot be determined by inspection, perform the following procedure.
7. Determine the type of fluid leaking. Make sure the leak is transmission fluid and not engine oil or brake fluid (automatic transmission fluid has a rich red color).
8. Try to pinpoint the source of the leak. Drive the car, then park the car with a large piece of cardboard underneath it. After one or two minutes, the source of the leak should be determined by the location of traces of liquid on the sheet.
9. Carefully inspect the element that may have a leak, as well as the area adjacent to it. Pay special attention to the seals of the mating surfaces. To inspect hard-to-reach areas, it is recommended to use a mirror.
10. If the above tests fail to determine the source, thoroughly clean with solvent and dry the area of possible leakage.
11. Drive for several kilometers at normal engine operating temperature and in various gears. After the run, again inspect the element that may be the source of the leak.
12. Having determined the location of the leak, determine and eliminate its cause before repairing it. If the connecting flange is deformed, then after installing a new gasket the leak may not stop - the flange must first be aligned.
13. Before you begin repairing a leak, make sure there are no leaks in the locations listed below.
Note: It is sometimes impossible to determine the presence of a leak in the locations listed below without the availability of special equipment and specific diagnostic procedures. In this case, contact a workshop with the appropriate level of competence and equipment.
Leakage through gasket
14. Inspect the pallet periodically. Make sure that all bolts are present and securely tightened, that the gasket is not damaged, and that there are no significant dents on the surface of the pan (dents on the pan can cause damage to the valve body, which is located inside).
15. The causes of leakage through the gasket may be excessively high level and pressure of the transmission fluid, clogged channels, excessive tightening of the pan bolts, deformation of the pan connecting flange, damage to the mating surface of the transmission housing, damage to the gasket or the flange of the gearbox casing. A leak can also occur due to the use of the wrong type of sealant to seal the connection between the engine pan and the transmission housing.
Leakage through seals
16. Causes of seal leakage may include excessively high transmission fluid levels and pressure, clogged passages, damaged seal sockets, improper installation or damage to the seal, damage to the shaft surface in contact with the seal, or excessive play in the bearings, which leads to excessive shaft runout.
17. Ensure that the dipstick tube is installed correctly and that the oil seal makes a tight seal. Periodically check the area around the drive gear or speedometer sensor for signs of transmission oil leakage. If the inspection reveals oil leaks, inspect the oil seal.
Leakage from casing
18. If a violation of the tightness of the gearbox casing is confirmed, this housing part should be restored or replaced.
19. Check that the oil cooler hose connectors are intact and secure. If a leak is detected, the first thing to inspect is the O-rings of the transmission oil cooler line couplings.
Fluid leaking from the dipstick tube or vent tube
20. Causes of leakage may include overfilling the gearbox, the presence of coolant in the transmission oil, cracking of the gearbox casing, the use of the wrong type of dipstick, as well as clogged ventilation tubes or oil return circulation channels.