The simplest is time delay test.
While the engine is idling and the driving mode selector is set to «D» or «R» from the neutral position, there must be a time delay before operation is felt. The purpose of this test is to check the performance of the components and mechanisms of the gearbox.
For safety reasons and to prevent damage, you must:
- before carrying out the test, warm up the gearbox well, the temperature of the automatic transmission should be at least 50-80°C;
- to achieve a high quality check, you need to take at least three measurements and determine their average value;
- to maintain the high performance of the automatic transmission, take one-minute breaks between measurements.
The time delay test is carried out as follows.
1. Fully raise the parking brake lever.
2. Start the engine.
3. Check the engine idle speed in the range «N». The engine idle speed should be 750-900 rpm. If the idle speed of the engine is not correct, then the measurement results will also be incorrect and the test will have to be repeated.
4. Move the driving mode select lever out of range «N» in the range «D».
5. Use a stopwatch to measure the time from the beginning of the movement of the handle to the moment the transmission operates. Measurements are recommended to be carried out at least three times and their average value determined. In this case, the time delay should be no more than 1.2 s.
6. Using the same method, take measurements when switching out of range «N» in the range «R». In this case, the time delay should not exceed 1.5 s.
When evaluating the results of the test, you must proceed from the fact that in the presence of any breakdown, the response time can only increase. Only a professional can find out the cause and fix the problem, so you need to urgently contact the appropriate service center.
Pretty simple and parking test. Its purpose is to check the performance of the engine, torque converter and gearbox as a whole.
To ensure safety and avoid breakdowns:
- it is necessary to carry out the test on a sufficiently light and wide area;
- the test should be carried out by two masters working in pairs: one of them should observe the wheels and their stops and immediately warn about turning the wheels or moving the stops, the second should carry out tests and record measurements;
- the duration of the test should not exceed 5 s.
Conducting the test and evaluating its results:
1. Be sure to secure the front and rear wheels.
2. If necessary, install a tachometer.
3. Apply the parking brake.
4. Press the brake pedal with your left foot and hold it in this position throughout the test.
5. Start the engine.
6. Set the driving mode select lever to the range «D».
7. Pressing the gas pedal with your right foot until it stops, fix the tachometer readings.
8. Take a break of at least one minute.
Repeat the test with the driving mode select lever in range «R». When evaluating this test, you need to know that each time you press the gas pedal, the tachometer needle should rise smoothly and stop in the range of 2400-2700 rpm. In this case, there should not be any extraneous noise, vibration and shock, and the car should remain in place.
If the tachometer reading:
- less than nominal, but the same in both ranges («D» And «R»), then most often the reason lies in insufficient engine power;
- higher than the nominal value in both ranges, then most likely the reason lies in a malfunction of the torque converter or gearbox;
- higher than the nominal value in one of the ranges, then it is most likely that the malfunction is only in the gearbox.
The most difficult to conduct and evaluate road test, which is carried out to determine the switching points, detect extraneous noise, vibration and slip in the gearbox.
To ensure safety, the test must be carried out on a sufficiently wide, level and empty section of the road; warm up the engine and gearbox well before driving.
Holding «road test» and its evaluation:
1. Set the driving mode selector to position «D» and, gradually pressing the gas pedal, check the presence of shifts of I-II, II-III, III-IV and IV-V gears. If there is no any of the switching, then the automatic transmission or its control and monitoring unit is faulty; if the switching points are tightened, then the problem is most likely in the control system.
2. Fix the speed of 70km/h in the «D» and depress the gas pedal a little. Engine speed should not change abruptly. If a sharp jump in engine speed is observed on the tachometer, then it can be argued that the torque converter is faulty, and it will soon completely fail.
3. Stop and move the drive mode select lever into the manual shift range. Gradually depressing the gas pedal, check the presence of the switch I-II. When moving in second gear, release the accelerator pedal and note the presence of engine braking. After repeating this operation several times, make sure that the shifts I-II and II-I are not accompanied by vibration, shock or slippage. If there are no negative phenomena, then the box is in good condition.
4. Come to a complete stop and move the lever to the «1» and gently pressing the gas pedal, make sure that there is no switching to the second stage, and also check for engine braking when the gas pedal is released. When repeatedly pressing and releasing the gas pedal, listen to the operation of the gearbox to identify extraneous noise and vibration. If there is a switch to the second stage or there is no engine braking, then the control and monitoring unit is faulty.
5. Stop and switch to range «R», depress the accelerator pedal sharply. After making sure that there are no slips, vibrations and extraneous noise, continue testing.
6. With the vehicle parked on an incline of about 5°, move the driving mode selector lever to the «R» and release the brake. The car must lock in place; if the car rolls, then the cause should be sought in the malfunction of the box parking mechanism.
We remind you that during the test you need to pay special attention to the presence of extraneous noise and vibration. They must be treated with due responsibility, since these noises and vibrations can be caused by an imbalance in the torque converter, drive shaft, etc., which can lead to unit failure.