Checking the mechanical systems of automatic transmission

Note: mechanical systems can be checked using the table "Checking the mechanical systems of automatic transmission".

Checking the torque converter on a fully braked vehicle (stall test)

Table. Checking the mechanical systems of the automatic transmission.



Table. Checking the pressure in the automatic transmission hydraulic control system.



Note: UD - Underdrive Clutch Pressure, RV - Reverse Clutch Pressure, OD - Overdrive Clutch Pressure, LR - 1st &Reverse Brake Pressure, 2ND - 2nd Gear Brake Pressure, DR - Lockout Release Pressure torque converter clutches.




1. Check.

Note: The purpose of this test is to measure the maximum engine speed with the output shaft of the automatic transmission fully braked on ranges "D" And "R". By the value of this frequency, it is possible to determine the performance of the overrunning clutch of the torque converter stator, as well as the presence of slipping of the friction clutches and brakes of the automatic transmission.

Attention: during this check, do not allow anyone to be in front of or behind the car.

• A) Make sure that the test conditions are met.

Verification conditions:

• The level of the working fluid in the automatic transmission: at the mark "NOT" probe
• Fluid temperature in automatic transmission: 80-100°C
• Engine coolant temperature: 80-100°C

• b) Install the brake pads under the rear wheels of the car.
• V) Fully raise the parking brake lever and fully depress the brake pedal.
• G) Start the engine.
• d) Set the automatic transmission selector lever to position "D", fully depress the accelerator pedal and determine the engine speed.
• Rated value: 2000-2900 rpm

Attention:

• Do not hold the throttle fully open for more than 8 seconds during this test.
• If this test needs to be done more than once. then after each check, move the automatic transmission selector lever to the position "N" and let the engine run at 1000 rpm for 2 minutes to cool the transmission fluid between checks.
• Move the selector lever to position "R" and recheck.

2. Analyze the test results.

• A) If the engine speed on a fully braked vehicle is in the ranges "D" And "R" greater than the nominal value, then the reason for this may be either low pressure in the hydraulic control system, or slippage (slippage) 1st gear and reverse gear brakes.
• b) If the engine speed on a fully braked vehicle is only in the range "D" greater than the nominal value, then the cause of this may be slippage (slippage) downshift clutches.
• V) If the engine speed on a fully braked vehicle is only in the range "R" greater than the nominal value, then the cause of this may be slippage (slippage) reverse clutches.
• G) If the engine speed on a fully braked vehicle is in the ranges "ABOUT" And "R" less than the nominal value, then the reason for this is either a malfunction of the torque converter, or insufficient (inadequate) engine power output.

Note: Check for misfires, ignition timing, etc. If no faults are found in all of the listed points, then the torque converter is faulty.

Hydraulic test

1. Measure the pressure in the line.

• A) Warm up the engine so that the automatic transmission fluid warms up to a temperature of 70-80°C.
• b) Raise the car on a lift until the drive wheels are hanging.
• V) Unscrew the service plug of the gearbox housing and connect a pressure gauge in its place.
• Service plug tightening torque: 8-10 Nm
• G) Measure the pressure of the working fluid in the line and check that the values obtained correspond to the nominal (see table "Checking the pressure in the automatic transmission control hydraulic system".

• d) After checking, tighten the service plug.
• e) Take measurements by connecting a pressure gauge in series to the ports marked: UD, RV, OD, LR, 2ND and DR.
• and) If the obtained values do not correspond to the technical data, then determine the cause and location of the malfunction. After troubleshooting, repeat the test.

2. Analyze the test results.

• A) High pressure in all lines (UD, RV, OD, LR, 2ND, DR) can be caused:
• improper adjustment of the automatic transmission control cable;
• pressure regulator failure.
• b) Low pressure in all lines (UD, RV, OD, LR, 2ND, DR) can be caused:
• improper adjustment of the automatic transmission control cable;
• malfunction of the automatic transmission pump;
• clogging of the internal or external filter of the automatic transmission fluid;
• malfunction of the pressure regulator;
• failure of the safety valve;
• improper installation of the solenoid valve block.
• V) Incorrect pressure only on the range "R" can be caused:
• malfunction of the pressure regulator;
• channel clogging;
• improper installation of the solenoid valve block.
• G) Inappropriate pressure only in 3rd or 4th gear can be caused by:
• malfunction of the pressure regulator;
• channel clogging;
• improper installation of the solenoid valve block;
• malfunction of the solenoid valve for controlling the overdrive clutch;
• malfunction of the pressure control valve in the overdrive clutch line;
• changeover valve failure.
• d) Inappropriate pressure in the underdrive clutch line only can be caused by:
• seal failure "TO", gland "L" or gland "M";
• malfunction of the solenoid valve for controlling the downshift clutch;
• malfunction of the pressure control valve in the line of the downshift clutch;
• malfunction of the ball valve;
• channel clogging;
• improper installation of the solenoid valve block.
• e) Improper pressure in the reverse clutch line only can be caused by:
• seal failure "A", gland "IN" or gland "WITH";
• channel clogging;
• improper installation of the solenoid valve block.
• and) Inappropriate pressure in the overdrive clutch line only can be caused by:
• seal failure "D", gland "E" or gland "F";
• malfunction of the solenoid valve for controlling the overdrive clutch;
• malfunction of the pressure control valve in the overdrive clutch line;
• malfunction of the ball valve;
• channel clogging;
• improper installation of the solenoid valve block.
• h) The discrepancy between the pressure only in the brake lines of the first gear and the reverse gear can be caused by:
• seal failure "I" or gland "J";
• malfunction of the solenoid valve for controlling the brake of the first gear and reverse gear;
• malfunction of the pressure control valve in the brake line of the first gear and reverse gear;
• switching valve malfunction;
• valve malfunction "A" emergency operation;
• malfunction of the ball valve;
• channel clogging;
• improper installation of the solenoid valve block.
• And) A pressure mismatch in the 2nd gear brake line only can be caused by:
• seal failure "G", gland "H", gland "ABOUT";
• malfunction of the second gear brake control solenoid valve;
• malfunction of the pressure control valve in the brake line of the second gear;
• valve malfunction "IN" emergency operation;
• channel clogging;
• improper installation of the solenoid valve block.
• To) Improper pressure in the reverse clutch line only can be caused by:
• malfunction of the automatic transmission oil cooler;
• seal failure "N";
• a malfunction of the solenoid valve for controlling the torque converter lock-up clutch;
• malfunction of the torque converter lock-up clutch control valve;
• malfunction of the pressure control valve in the torque converter;
• channel clogging;
• incorrect installation of the solenoid valve block.
• l) The working pressure in the line of the switched off control element can be caused by:
• improper adjustment of the automatic transmission control cable;
• malfunction of the range selection valve;
• malfunction of the ball valve;
• improper installation of the solenoid valve block.

Road test

1. Turn the ignition key to position "ON" and check the serviceability of the automatic transmission control relay (presence of battery voltage).

2. With the engine off, move the automatic transmission selector to the position "R" and do the following:

• A) Move the automatic transmission selector sequentially to the positions "R", "R", "N", "ABOUT", "2", "L". Check the operation of the start inhibit switch.
• b) Check the throttle position sensor. Measure the voltage at the sensor terminals.

Rated voltage:

• with the accelerator pedal released: 400-1000 mV
• when the accelerator pedal is not fully depressed: increases from 400 mV
• with the accelerator pedal depressed: 4500-5000 mV

• V) Check up serviceability of the switch of stoplights at the pressed and released brake pedal.

3. Turn the ignition key to position "START". Move the automatic transmission selector to position "R" or "N", and make sure the engine start (crankshaft cranking by starter) possible only in the indicated selector positions.

4. Drive the vehicle for 15 minutes or more and check the transmission fluid temperature sensor (the temperature gradually increases to 70-90°С).

5. With the engine idling, move the automatic transmission selector to the position "N" and do the following:

• A) Including "ON" on and off "OFF" air conditioner, check the triple refrigerant pressure switch.
• b) Make sure the throttle is in the fully closed position with the accelerator pedal released and not fully depressed.
• V) Check the crankshaft position sensor with the accelerator pedal released and not fully depressed.
• Sensor readings: 650-900 rpm
• G) Check communication with the electronic engine control unit with the pedal released and with the pedal not fully depressed.
• d) Moving the selector from position to position and from position to position, make sure that there are no malfunctions (jolts) at the start of movement and delays (more than two seconds) gear shifting.

6. Moving along a straight horizontal section of the road, move the automatic transmission selector to the position "D", check that the gears engaged correspond to the specified speed within 10 seconds.

• A) The engine is idling - the automatic transmission selector is in position "L" - the vehicle is stationary.
• b) Automatic transmission selector in position "L" A car is moving at a constant speed of 10 km/h.
• V) Automatic transmission selector in position "2" The car is moving at a constant speed of 30 km/h.
• G) Automatic transmission selector in position "3" A car is moving at a constant speed of 50 km/h.
• d) Automatic transmission selector in position "D" A car is moving at a constant speed of 50 km/h.

7. For the conditions of subparagraphs "A" And "G" item "6" check the vehicle speed sensor.

8. For the conditions of subparagraph "G" item "6" check the serviceability of the gearbox input shaft speed sensor (1800 -2100 rpm) and gearbox output shaft speed sensor (1800-2100 rpm).

9. Moving along a straight horizontal section of the road, move the automatic transmission selector to the position "D", check gear shifting.

• A) Accelerate the vehicle until the automatic transmission shifts into fourth gear when the throttle is opened by 30% (throttle position sensor voltage 1.5V).
• b) Slowly brake until the vehicle stops.
• V) Accelerate the vehicle until the automatic transmission shifts into fourth gear when the throttle is opened to 50% (throttle position sensor voltage 2.5V).

Note: make sure that there are no sudden shocks during the checks described in subparagraphs "A" - "V".

• G) When driving in fourth gear at 40 km/h, shift to third gear.
• d) When driving in third gear at 30 km/h, shift to second gear.
• e) When driving in second gear at 20 km/h, shift to first gear.

Note: make sure to immediately downshift after moving the automatic transmission selector during the checks described in subparagraphs "G" - "e".

10. Move the automatic transmission selector lever from the position "N" into position "R" and check that reverse gear is engaged. When driving on a straight, level road at a speed of 10 km/h, check that the ratio between the values of the transmission speed sensor input speed sensor and the transmission speed output speed sensor signals is equal to the gear ratio when the reverse gear is engaged.