Mercedes M-Class W163
since 1997 release
Repair and operation of the car
+ Mercedes-Benz cars of a class M (W163)
+ Governing bodies and methods of safe operation
+ Current leaving and service
+ Cooling systems, heating and air conditioner
+ A power supply system and production of the fulfilled gases
+ Systems of electric equipment of the engine
+ Manual box of gear shifting
- Automatic transmission
Search of malfunctions - the general information
The general principles of functioning of system transmission, the operating signals
Adjustment of the drive of switching of AT
Removal and installation of the electrohydraulic control unit of switchings
Removal and the AT installation with the hydrotransformer
Removal and installation of the selector module
Removal and installation of a cable of blocking of the electronic switch of ignition (EIS)
+ Transmission line
+ Brake and auxiliary systems
+ Suspension bracket and steering
+ Onboard electric equipment
At the time of start-off from the place the automatic transmission (AT) acts as ordinary coupling, and during the movement performs work on gear shifting. On all models considered in the present manual series 722.6 AT are established.
The AT main hubs are: torque converter (hydrotransformer), planetary reducer and hydraulic or electronic control unit. Hydrodriving disk brakes and disk coupling are applied to transition to other transfer relation in a planetary reducer. The design of typical AT is shown on an illustration.
Design of typical AT
The torque converter on the functions corresponds to hydraulic coupling. Its task includes implementation of coupling at start-off from the place and gear shifting.
The control system of transmission (known also as electronic system of synchronous switching) is a component of the modified control system of the engine installed only on model with AT. The control system can work in special emergency (safe) operation with a limited range of switchings into which passes at detection of any malfunction (on the dashboard the special control lamp is activated (see the Head Governing bodies and methods of safe operation). Switching in emergency operation allows to drive away the car under the own steam on car repair shop for performance of detailed diagnostics and necessary recovery repair. On the basis of the analysis of the data arriving from various information sensors (not necessarily directly related to functioning actually of transmission), the module of management of transmission (TCM) chooses optimum from the point of view of profitability, smoothness of switchings and so forth the mode of functioning of AT. At a certain provision of a butterfly valve of TCM can issue the command for the blocking of the hydrotransformer leading to restriction of switchings of AT with the range only of the 4th and 5th transfers that promotes considerable reduction of fuel consumption.
The only procedure of service of AT which implementation has to be made on a regular basis is check of level of working liquid (ATF) which order of performance is stated in the Head the Current leaving and service. Need for regular replacement of ATF is absent.
Near a radiator of the cooling system of the engine ATF cooler is established.
On the basis of the data arriving from the mode kickdown, TCM which is traditionally set under the accelerator pedal of the sensor switch of activation carries out switching of transmission on adjacent the pedal which is used at the moment transfer at full squeezing that allows to raise significantly dynamic characteristics of the car, for example during overtaking commission.
There are several operating modes of transmission, each of which can be involved after moving of the selector to one of the following provisions: "P", "R", "N", "D", "1", "2", "3", "4" (address the Head Governing bodies and methods of safe operation). Since 01.09.99 on all models selector modules with function of the consecutive choice of ranges of the mode of the movement "D" (1, 2, 3 and 4) when transfer of AT to the mode of restriction of ranges of switchings (4, 3, 2 and 1) is carried out by side push-ups of the lever (D+/D-) began to be installed electronic (see the Section Start of motion and gear shifting).
Thanks to use of the special N/P sensor switch start of the engine can be carried out only when the lever of the AT selector is in situation "P" or "N" that allows to prevent casual start-off of the car in start attempt.
In the present Chapter only the most general procedures of service of AT lying within qualification of the average amateur mechanic are considered. More detailed information on a design, the principles of functioning and service of AT of a series 722.6 can be found in the Managements No. 179 ("Automatic transmissions of modern cars") and No. 187 ("Mercedes of the S-class W-203") of ARUS publishing house.