Note: this chapter is given in an abbreviated version, since any work on the repair of automatic transmission should be carried out in a specialized service center.
General information
Gearbox Description
The A343F automatic transmission consists of a torque converter with a lock-up clutch, a step-up planetary gear set, a three-speed gearbox and a control system that includes hydraulic and electronic parts.
The planetary gearbox consists of several planetary gear sets and has a design similar to the A340E transmission, which was used on Toyota Crown, Mark II, Chaiser, Cresta cars.
To control the automatic transmission, a selector for selecting the range of the gearbox is installed in the cabin. The selector is connected with a cable to the valve box on the automatic transmission. In addition to the selector in the cabin, there are several switches to set special modes of operation of the gearbox.
To prevent damage to the automatic transmission if the range is incorrectly selected (for example, moving from "D" V "R" when moving forward) a latch is installed on the lever, only when pressed, it is possible "dangerous" switching. The latch allows you to avoid a situation where, through negligence, one of the ranges of motion can be turned on and the car starts to move uncontrollably. When the battery is discharged or disconnected, the selector is locked in position "R". There is a dedicated button to release the lock (Red), located on the console.
Description of the hydraulic part of the control system
The hydraulic part of the control system consists of an oil pump, a valve box, solenoid valves, lockup clutches and brakes, as well as channels connecting all these elements. The pressure of the working fluid created by the pump is used to control the friction elements of the gearbox, feed the torque converter and lubricate.
On signals from the transmission control unit, the shift solenoid valves control the passage of fluid that enters the torque converter and planetary gearbox.
Description of the electronic part of the control system
The electronic part controls gear shifting in the gearbox, as well as the torque converter lock-up clutch. It consists of three parts:
1. Sensors - determine the vehicle speed and other parameters, and transmit them to the electronic transmission control unit.
2. The electronic control unit of the gearbox, which, based on the analysis of the data coming to it, determines the shift points in the gearbox, and also controls the torque converter lock-up clutch.
3. The executive part, which consists of several solenoid valves.
Selector positions
The choice of the range of operation of the gearbox is carried out by moving the selector to the appropriate position, indicated by the letters "R", "R", "D", "N", "2" or "L".
Position"R"
Recommended for long-term car parking. In this selector position, all controls are disabled in the gearbox and the output shaft is blocked, the vehicle cannot move. To move the selector to this position is permissible only at a complete stop.
Attention: transfer of the selector to the position "R" while driving may damage the transmission.
Position "R"
Reverse mode. The selector can only be moved to this position when the vehicle is stationary.
Attention: moving the lever to the position "R" while moving forward, it can lead to failure of the gearbox and other transmission components.
Position "N"
Corresponds to neutral. In the gearbox, either all controls are turned off, or only one is turned on, which ensures that there is no rigid kinematic connection between its drive and driven shafts. In this case, the output shaft blocking mechanism is disabled, i.e. the car can move freely.
Attention:
- It is not recommended to move the range select lever to the position "N" while coasting (by inertia).
- Never turn off the ignition when driving downhill. This practice is dangerous because it could cause you to lose control of the vehicle.
Position "D"
The main driving mode, which provides automatic switching from first to fourth gear. In normal driving conditions, it is recommended to use it.
Mode "OD" (overdrive)
Permission to use the fourth overdrive is carried out using a special button "O/D".
If the button is in the depressed position and the range select lever is in the "D", then shifting to fourth gear is permitted. Otherwise, the inclusion of the fourth gear is impossible. The status of the control system is indicated by the indicator "O/D OFF". If overdrive is allowed (normal mode) the indicator does not light, but when disabled, it lights up.
Mode "O/D" (button recessed) used when driving at a low-changing high speed on high-speed roads. If possible, do not use this mode in the city, especially on a winter road - this excludes overdrive from work and allows you to more efficiently use the engine braking mode.
Attention:
- Do not enable mode "O/D" when the vehicle is fully loaded.
- Turn off the mode "O/D", if there are frequent shifts from 3rd to 4th gear and back to prevent increased wear of automatic transmission parts.
Position "2"
Driving is allowed only in first and second gears. Recommended for use, for example, on winding mountain roads. Switching to third and fourth gears is prohibited. In this range, the engine braking mode is effectively used.
Position"L"
Driving is allowed only in first gear. This range allows maximum implementation of the engine braking mode. It is recommended when driving on steep descents, climbs and off-road.
Special programs
Two options are programmed in the memory of the electronic control unit (programs) gear shift control: "economical" And "sports".
"economical" program (normal mode)
The program is tuned to ensure movement with minimal fuel consumption. In this case, upshifts occur approximately when the engine speed reaches the average values, which corresponds to the minimum on the fuel consumption characteristic. The movement of the car in this case is smooth, calm.
"Sports" program
This program is set to maximize the use of engine power. Therefore, upshifts occur in the region of maximum engine speed, at which the engine develops maximum power.
The car in this case develops, in comparison with "economical" program, significantly greater acceleration.
When this program is turned on, the indicator lights up "ECT PWR", located on the dashboard to the left of the steering column.
Mode "kick-down"
If you press the throttle pedal to the stop, then the gearbox shifts one or two gears down. This mode is recommended to be used to obtain higher acceleration values, which is useful, for example, during overtaking. Reverse upshifting in this case can only occur when the engine reaches maximum speed. If you release the throttle pedal, the transmission will return to normal operation.
It should be borne in mind that on a slippery road during a forced downshift, the drive wheels may slip, which can lead to a skid.
High fluid temperature indicator
The gearbox control unit monitors the temperature of the working fluid using a temperature sensor. The fluid temperature may become excessively high when the vehicle is operated under heavy load, such as when driving on sand or uphill. If the temperature rises to 150°C or more, the control unit turns on an indicator located on the center console. The indicator goes out when the temperature drops below 120°C.
Transmission park indicator
The cardan shafts and wheels of the car can rotate freely, even when the selector on the gearbox is set to the position "R" (parking), if the transfer case shift lever is in position "N" (neutral).
In this case, to warn the driver that the driveshafts and wheels are not locked, the automatic transmission parking mode indicator lights up. If the parking mode indicator turns on, it is necessary to move the transfer case shift lever from the position "N" (neutral) to any other position.