Attention! The main reasons for abnormal transmission operation may be engine failure (loss of power), incorrect adjustments, failures of the hydraulic transmission system, mechanical drive and processor control system. First of all, you should check the level and condition of the fluid, adjust the rods. If these measures do not lead to a positive result, then you should contact a car service.
Preliminary checks
1. Warm up the transmission by driving.
2. Check the fluid level and condition.
3. If the level is below normal, restore the level and check for leaks (see below).
4. If the level is above normal, drain some of the fluid and check for contamination from coolant that may have entered due to a leak in the radiator.
5. If foaming is detected, drain the fluid and replace it.
6. Check the engine idle speed. Repair and adjust if necessary, as further testing of the transmission is pointless.
7. Check the adjustment and operation of the mechanical transmission drive.
Checking the condition of the transmission for fluid leaks
1. Fluid leaks are easily detected visually and can be eliminated by replacing seals or gaskets.
2. To detect a barely noticeable leak, park the car after driving for several kilometers over a clean sheet of cardboard or paper. After about 2 minutes, the leak can be detected.
3. Clean the crankcase immediately and check the condition of the seals in suspect areas.
4. If the leak is not detected in this way, then thoroughly rinse the crankcase with solvent and dry it.
5. Take a drive and inspect the crankcase carefully.
6. If the leak location is identified, determine the cause of the leak and the repair method (for example, replacing the gasket cannot eliminate the leak if the separating surfaces are deformed).
7. Before eliminating the leak, analyze the causes of the leak and ensure that the faults described below are eliminated.
Attention! Some types of work to eliminate the following faults can only be performed in a car service center, as special tools and certain qualifications are required.
Leak from under the gasket
1. Periodically check the condition of the transmission pan, the tightening of the bolts, the condition of the pan split plane and gasket.
2. The causes of leaks from under the pan gasket may be an increase in pressure or liquid level due to clogged ventilation holes, deformation of the pan or its split plane, non-compliance of the sealant brand used with the recommended one, or defects in the pan casting.
Leak from under the oil seal
1. A seal leak may be caused by increased pressure or fluid level due to clogged vents, improper seal installation, damage to the shaft seal journal, or bearing wear.
2. Periodically check the tightness of the seal of the indicator pipe and the speedometer gearbox.
3. If a leak is detected, replace the sealing ring.
Crankcase leak
1. Crankcase leakage is caused by casting defects, in this case repair or replace the crankcase.
2. Check the tightness of the liquid cooler hoses.
Leak from breather or filler pipe
A breather leak indicates an overfilled transmission, coolant ingress, porosity of the crankcase material, incorrect position of the indicator, clogged ventilation and drainage channels.
Road testing
Test with selector in DRIVE range
1. Move the selector to DRIVE range and accelerate the vehicle.
2. Move the selector to positions 1–2, 2–3 or 3–OD.
3. The torque converter should lock up in 1st or 2nd gear, or OD gear. Press the throttle pedal 3/4 of the way down and the transmission should downshift.
Test with selector in RANGE 2 position
1. While driving, shift the transmission to RANGE 2.
2. The transmission should immediately downshift and not shift back to Overdrive.
3. Check downshifting at partial and full throttle.
LOW range
1. Move the selector to the LOW position.
2. Check the operation of the transmission.
Checking braking in different driving modes
Coasting at high initial speed
1. Move the selector lever to a low range gear.
2. The engine speed should increase and a braking effect should be felt.
Reverse
1. Move the selector to the REVERSE position.
2. Check the operation of the transmission.
General checks
1. Check the engine for proper operation and adjustments.
2. Check the throttle cable adjustment.
3. Check the condition of the transmission hoses and wiring.
4. Check the transmission selector adjustment.
5. If after these checks the transmission still does not operate normally, contact a service center to have the transmission line pressure checked.