| General information | |
| Type | 5-speed, automatic with electronic gear shift control |
| Designation | |
| 722.661 |
| 722.666 |
| 722.660 |
| 722.662 |
| 722.674 |
| 722.663 |
| ATF type and volume | See Specifications for Chapter Routine care and maintenance. |
| For diagnostic codes of the electronic control system of automatic transmission, see Chapter Engine electrical systems. | |
| Gear ratios and operation diagram of AT 722.6 activators | |||||||||
| Broadcast | Gear ratio | B1 | B2 | B3 | K1 | K2 | K3 | F1 | F2 |
| 1 | 3.93:1 | X* | X | X* | X | X | |||
| 2 | 2.41:1 | X | X | X* | X | ||||
| 3 | 1.49:1 | X | X | ||||||
| 4 | 1.00:1 | X | X | ||||||
| 5 | 0.83:1 | X* | X | X | |||||
| N | X | X | |||||||
| R (S mode) | -3.10:1 | X* | X | X | X | ||||
| R (W mode) | -1.90:1 | X | X | X | |||||
* Switch activators only in kickdown mode | |||||||||
| Automatic Transmission Control System Diagnostic Codes Retrieved with an OBD II Scanner | |||||||||
Refer to Specifications in Chapter Engine electrical systems. | |||||||||
| Tightening force of threaded connections, Nm | |||||||||
| Shift Rod Head Bolt | 12 | ||||||||
| Transmission Oil Pan Drain Plug | 20 | ||||||||
| Bolts for fastening the sump to the crankcase | 8 | ||||||||
| Bolts securing heat shield to transmission housing | 8 | ||||||||
| Bolts for fastening the electrohydraulic control unit to the transmission housing | 8 | ||||||||
| Bolts securing selector lever assembly to floor panel | 6 | ||||||||
When starting off, the automatic transmission (AT) acts as a regular clutch, and during movement it performs the work of shifting gears. All models considered in this Manual are equipped with AT series 722.6.
The main components of the AT are: torque converter (torque converter), planetary gearbox and hydraulic or electronic control unit. To change gear ratios, hydraulically driven disc brakes and disc clutch are used in the planetary gearbox. The design of a typical AT is shown in the illustration.
Typical AT design
1 - Input shaft; 2 - Electro-hydraulic shift control unit; 3 - Intermediate shaft; 4 - Parking lock gear; 5 - Output shaft; 6 - Oil (ATF) pump; 7 - Torque converter; 8 - Reactor shaft; 9 - Torque converter lock-up clutch; 10 - Multi-disc brake assembly B1; 11 - Multi-disc brake assembly B2; 12 - Multi-disc brake assembly B3; 13 - Overrunning clutch F1; 14 - Overrunning clutch F2; 15 - Rear planetary assembly H; 16 - Multi-disc clutch K1; 17 - Multi-disc clutch K2; 18 - Multi-disc clutch K3; 19 - Central Planetary Assembly M; 20 - Front Planetary Assembly V
The torque converter functions like a hydraulic clutch. Its job is to provide clutch when starting off and changing gears.
Transmission control system (also known as electronic synchronous switching system) is a component of a modified engine management system, installed only on models with AT. The control system can operate in a special emergency (safe) a mode with a limited switching range, which it switches to when any malfunction is detected (a special control lamp is activated on the instrument panel (see Chapter Controls and safe operating techniques). Switching to emergency mode allows you to drive the car under its own power to a service station for detailed diagnostics and necessary repairs. Based on the analysis of data coming from various information sensors (not necessarily directly related to the functioning of the transmission itself), the transmission control module (TCM) selects the optimal mode of operation of the AT in terms of economy, smoothness of shifting, etc. At a certain position of the throttle valve, the TCM can issue a command to lock the torque converter, which leads to limiting the AT shifting to the range of only 4th and 5th gears, which contributes to a significant reduction in fuel consumption.
The only maintenance procedure for the automatic transmission system that must be performed on a regular basis is to check the working fluid level (ATF), which is described in the Chapter Routine care and maintenance. There is no need for regular replacement of ATF.
An ATF cooler is installed next to the engine cooling system radiator.
Based on data received from the traditionally installed under-the-gas-pedal kickdown switch sensor, the TCM switches the transmission to a gear adjacent to the one currently in use when the pedal is fully depressed, which significantly improves the vehicle's dynamic performance, for example when overtaking.
There are several transmission operating modes, each of which can be engaged by moving the selector to one of the following positions: "P", "R", "N", "D", "1", "2", "3", "4" (refer to Chapter Controls and safe operating techniques). Starting from 01.09.99, all models began to be equipped with electronic selector modules with the function of sequential selection of the ranges of the driving mode "D" (1, 2, 3 and 4), when the AT is switched to the switching range limitation mode (4, 3, 2 and 1) is carried out by lateral pressing of the lever (D+/D-) (see Section Starting off and changing gears).
Thanks to the use of a special N/P switch sensor, the engine can only be started when the AT selector lever is in the "P" or "N" position, which prevents accidental starting of the car when trying to start it.
This Chapter covers only the most general AT maintenance procedures that are within the skill level of the average amateur mechanic.