Subaru Legacy/Outback

1999-2003 of release

Repair and operation of the car

Control system of speed (tempostat) - the device and the principle of functioning

General information

The models of cars considered in the present manual are equipped with system of additional safety (SRS). Before starting performance of any works near the block of a safety cushion, a steering column or the dashboard, disconnect SRS in order to avoid receiving injuries at its casual operation (see the Section System of Additional Safety (SRS) - the device and the principle of functioning)! It is easy to distinguish an electrical wiring of a chain of SRS on yellow color of isolation.

Tempostat provides automatic deduction of cruiser speed of the movement of the car at the level chosen by the driver.

At the movement of the car under a bias or uphill the high-speed mode can change.

Scheme of placement of the main managing directors of components of a tempostat


1 — the Actuation mechanism (servo-driver) 2 — the Sensor switch of permission of start (model with AT) 3 — the Operating switch of a tempostat 4 — the Main switch of a tempostat	5 — the coupling Sensor switch (models with RKPP) 6 — the stoplights/braking Sensor switch 7 — the Module of management of a tempostat

At activation of a tempostat, the module of management of system starts comparing the data issued by the speed sensor (models to RKPP) / TCM (models to AT) to the uka chosen by the driver at activation of a tempostat. On the basis of results of comparison the module develops the correcting teams transferred to the actuation mechanism of a tempostat installed in a motive compartment which is directly operating the drive of a butterfly valve. The scheme of an arrangement of the main managing directors of components of a tempostat is shown on an illustration.

Principle of functioning

The function chart of a control system of speed is presented on an illustration.

Keeping of the chosen cruiser high-speed mode

If the actual speed of the car of time exceeds at the moment the adjusting value entered into memory of the module of management, the module of management of a tempostat by means of activation of the built-in servomotor of the actuation mechanism carries out the prikryvaniye of a butterfly valve providing the demanded reduction in the rate of the movement of the car. The same scheme is involved in an opposite situation when the current speed is insufficient, in the opposite direction, providing a due priotkryvaniye of a throttle.

Mechanism of a choice of the cruiser high-speed mode

Push-up of the combined operating switch of a tempostat in the situation "SET/COAST" in the position "ON" of the main switch of a tempostat at the movement of the car with a speed not less than 40 km/h (25 miles/h) leads to giving of current on the actuation mechanism of a control system of speed. Activation of the coupling of coupling of the actuation mechanism leads to start of the driving electric motor providing removal of a butterfly valve in the situation corresponding to the current provision of a pedal of gas therefore the car starts moving with the constant cruiser speed equal to speed which it had at the time of activation of system.

Acceleration/braking

Push-up of the operating switch in the situation "RESUME/ACCEL" at the activated control system of speed leads to temporary acceleration of the car at the expense of a priotkryvaniye of a butterfly valve, - at an otpuskaniye of the switch there has to be a return to the cruiser speed of the movement.

Temporary dumping of speed due to braking by the engine is made by keeping of the operating switch wrung out in the situation "SET/COAST" (with return to the chosen cruiser speed at a switch otpuskaniye).

At reduction in the rate of the movement of the car lower than 32 km/h (20 miles/h) tempostat it has to be disconnected automatically.

Return to the installations chosen earlier after temporary shutdown of a tempostat

Return to the installations of the cruiser high-speed mode chosen earlier after temporary shutdown of a tempostat is made by push-up of the operating switch in the situation "RESUME/ACCEL".

The current speed of the movement of the car at the time of a call of installations has to make not less than 32 km/h (20 miles/h).

It is necessary to remember that transfer of the main switch of a tempostat to the situation "OFF", as well as switching off of ignition leads to deleting of the installations which are earlier entered into memory of the module of management of a tempostat.

Shutdown of a tempostat

Deactivation of a tempostat can be made by any of the listed below ways:

a) The squeezing of a pedal of a foot brake leading to activation of the sensor switch of stoplights/braking;
b) The squeezing of a pedal of coupling (model with RKPP) leading to activation of the corresponding sensor switch;
c) Transfer of the lever of the selector to the situation "N" (models with RKPP) leading to activation of the sensor switch of permission of start;
d) Push-up of the operating switch of a tempostat in the situation "CANCEL";
e) Ignition switching off;
f) Transfer of the main switch of a tempostat to the situation "OFF" (Vykl).

High-speed restrictions

At reduction in the rate of the movement of the car below a mark of 32 km/h (20 miles/h) there is an automatic shutdown of a tempostat, - the system can work rather effectively only at speeds of movement not lower than 40 km/h.

Mechanism of correction of involuntary acceleration / braking

When as a result of involuntary dispersal of the car (for example, at the movement under a bias) the current speed starts exceeding a preset value more than on 10 km/h (6 miles/h), the module of management of a tempostat makes necessary adjustment due to shutdown of the coupling of coupling of the actuation mechanism.

At involuntary reduction of the high-speed mode (for example, at the movement uphill) more than on 8 km/h (5 miles/h) of rather adjusting value the demanded adjustment is made due to activation of the coupling of coupling of the actuation mechanism.

Actuation mechanism

When receiving the corresponding signal from the module of management the turning on of the coupling of coupling of the actuation mechanism providing activation of the step servomotor which is directly connected with a butterfly valve is made. The design of the actuation mechanism is presented on an illustration.

Main switch

By means of the main switch management of giving of food on the module of management of a tempostat is made. The switch is equipped with the built-in control lamp and a lamp of illumination.

Shutdown of ignition leads to machine translation of the main switch of a tempostat in the situation "OFF" (Vykl).

The combined operating switch

The combined operating switch has a self-returnable lever design and is located on assembly of a steering wheel that allows the driver to carry out the demanded switchings without coming off driving. The corresponding contacts of the switch remain in the closed state until the lever keeps wrung out in any of working provisions, at a lever otpuskaniye the switch automatically comes back to a basic position. Procrastination of the lever of the switch on the driver leads to the translation it in the situation "CANCEL" when signals of "RESUME/ACCEL" and "SET/COAST" are sent on the module of management at the same time.

Sensor of speed of the movement (VSS)

VSS is established on a case of transmission and (on models with RKPP) provides the module of management of a tempostat of information on the current speed of the movement of the vehicle.

Drive of a butterfly valve

The butterfly valve is equipped with two driving cams, to one of which the gas cable connected to an accelerator pedal while the second serves for connection of a driving cable of the actuation mechanism of a tempostat fastens.

1 — a gas Cable
2 — the Cable of a tempostat
3 — the Cam

Both cams function independently from each other, otherwise, movement of one not necessarily involves movement of the second.

Module of management

The module of management of a tempostat is located in the lower part of the right forward rack and provides complete control of functioning of a control system of speed, being based the analysis of the data arriving from the corresponding information sensors and sensors switches.

Function of an emergency shutdown

Repeated deactivation of a tempostat after its emergency shutdown on any of the reasons can be carried out later not less than 2 ÷ 20 minutes about the violation identification moment.

The emergency shutdown of a tempostat occurs in the listed below situations.

The conflict between signals of the operating switches and sensors switches of deactivation of a control system of speed

The automatic emergency shutdown of a tempostat makes at transfer of the managing director of the switch to any of working provisions (SET/COAST, RESUME/ACCEL or CANCEL) at simultaneous development any of the deactivating signals (braking, operation of the sensor switch of stoplights, couplings or permissions of start).

Transfer of the main switch to the situation "ON" is one more reason of automatic shutdown of a tempostat at the operating switch which is wrung out in any of working provisions.

Repeated activation of a tempostat after its emergency shutdown can be made only after transfer of the main switch to the situation "OFF".

Violations in a chain of electric connections

Can lead the following electric violations to an emergency shutdown of a tempostat:

a) Grounding or a detachment of the plug of the step servomotor / disconnection of a chain of the drive of the motor as a result of short circuit;
b) Short circuit in a chain of the coupling of coupling of the servomotor;
c) Speed signal variations with an amplitude ± 10 km/h and the period of 350 ms;
d) Burning in the built-in relay during deactivation of a tempostat;
e) Violation of serviceability of functioning of the module of management of a tempostat;
f) A divergence between the values which are written down in the RAM of the module of management;
g) Identification of self-diagnostics of any violations of a tempostat by system at ignition inclusion.

Violation of serviceability of functioning of the step servomotor

Failures of the step motor of the actuation mechanism, and also too frequent and excessively long its inclusions can also lead to emergency deactivation of a tempostat.