General information
Cars are equipped with the following systems:
- speed control, which allows you to maintain the speed selected by the driver. This function can be disabled at any time by pressing the brake pedal or one of the system switches.
- speed limit, which allows the driver to set a speed limit. If it is exceeded, the impact on the accelerator pedal does not lead to an increase in vehicle speed. The selected speed can be increased at any time by pressing the accelerator pedal over the point of resistance.
Pic. 7.92. Block diagram of the speed control and limitation system: 1 - switch (regulator) speed limiter; 2 - switches on the steering wheel; 3 - accelerator pedal; 4 - instrument panel; 5 - clutch travel sensor (if it is installed); 6 - stoplight switch; 7 - central electronic switching unit in the cabin; 8 - ABS ECU; 9 - ECU of the injection system
Feature management «Travel speed control» and «Movement speed limit» carried out by the injection computer. This unit communicates with ABS ECU, UCH, AT ECU (if it is installed) and instrument panel. The injection computer implements the setpoints by issuing control commands to the servo throttle valve or by adjusting the diesel fuel supply.
Note. A flashing warning light on the instrument panel indicates that the set speed cannot be maintained (e.g. when driving downhill).
Description of the system
The UCH sends information «brake pedal pressed» (signal from the make contact of the brake light switch).
The ABS ECU sends information about the vehicle's speed.
ECU automatic transmission (if she is) sends information about the enabled transmission.
The selected speed value is displayed on the instrument panel (for regulated or limited) and the symbol of the enabled function (tricolor signal lamp).
Each time these functions are activated, the on-board computer display switches to the corresponding page.
Note. There is no malfunction indicator light for the maintain and speed limit functions.
Governing bodies
A three-position switch enables and disables the governor or speed limiter.
The steering wheel switches are used to change the set speed, cancel a function or recall the speed from memory.
The accelerator pedal position sensor and brake light switch are used in common with the injection system.
The clutch pedal travel sensor is designed specifically for the cruise control function. This sensor can also be used by the injection system.
Note. The car has two clutch pedal position sensors: for starting the car (pedal end sensor) and for the speed control system (pedal start sensor).
Note. The accelerator pedal has a safety switch at the end of travel.
injection computer.
The injection computer receives via the multiplex network:
- vehicle speed information (from ABS ECU);
- signal from the make contact of the brake light switch (from the CECBS);
- information about the included transmission (from the automatic transmission computer, if installed).
The injection computer sends over the multiplex network:
- the set value of the adjustable or limited speed on the instrument panel;
- a signal to turn on the two-color signal lamp on the instrument panel with a constant or flashing light;
- control commands to the throttle valve with a servo drive or to the diesel fuel supply regulator;
- information about gear shifting automatic transmission (if it is installed).
The injection computer receives information via wired communication:
- from the accelerator pedal position sensor;
- from the stoplight switch (has two contacts: opening and closing);
- from the clutch pedal travel sensor (if he is);
- three-position switch signal;
- from the steering wheel controls.
Speed limiter
Activation conditions:
- switch in position «speed limiter» (30 km/h - minimum speed, 200 km/h - maximum speed);
- pressing switches «+», «–» or «R».
Shutdown conditions:
- hard pressing on the accelerator pedal (overcoming the point of resistance);
- switch in position «turned off»;
- pressing the switch «0»;
- injection computer intervention (in case of malfunction or exceeding the maximum allowable speed).
Note. A flashing warning light on the instrument panel indicates to the driver that the set speed cannot be maintained.