The vehicles are equipped with the following systems:
– Cruise control, which allows the driver to maintain a speed selected by the driver.
This function can be deactivated at any time by pressing the brake pedal or one of the system switches.
– Speed limiting, which allows the driver to set a maximum speed.
If the maximum speed is exceeded, pressing the accelerator pedal does not increase the vehicle's speed.
The selected speed can be increased at any time by pressing the accelerator pedal past the resistance point.
Fig. 1. Block diagram of the speed control and limiting system: 1 - speed limiter switch (controller); 2 - switches on the steering wheel; 3 - accelerator pedal; 4 - instrument cluster; 5 - clutch travel sensor (if installed); 6 - brake light switch; 7 - central electronic switching unit in the cabin; 8 - ABS ECU; 9 - Injection Control Unit
The "Cruise Control" and "Cruise Limiter" functions are controlled by the injection control unit.
This unit exchanges information with the ABS control unit, the UCH, the automatic transmission control unit (if equipped), and the instrument cluster.
The injection control unit implements the set values by issuing control commands to the motorized throttle body or by regulating the diesel fuel supply.
Description of System Operation
The UCH sends the "brake pedal pressed" signal (a signal from the brake light switch's normally open contact). The ABS control unit sends information about the vehicle's speed.
The automatic transmission control unit (if equipped) sends information about the gear engaged.
The instrument cluster displays the selected speed (for adjustable or limited) and the symbol for the active function (a three-color warning lamp).
Each time these functions are activated, the trip computer display switches to the corresponding page.
NOTE: There is no malfunction warning lamp for the cruise control or limiter functions.
Controls
A three-position switch switches the cruise control or limiter on and off.
The switches on the steering wheel are used to change the set speed, cancel the function, or recall a speed value from memory.
The accelerator pedal position sensor and brake light switch are shared with the injection system.
Travel sensor The clutch pedal position sensor is designed specifically for the cruise control function.
This sensor can also be used by the injection system.
The vehicle is equipped with two clutch pedal position sensors: one for starting the vehicle (the end-of-stroke sensor) and one for the cruise control system (the beginning-of-stroke sensor).
The accelerator pedal has a safety switch at the end of its stroke.
Injection ECU
The injection ECU receives via the multiplex network:
- – vehicle speed information (from the ABS ECU);
- – signal from the brake light switch normally open contact (from the UCH);
- – information about the gear engaged (from the automatic transmission ECU, if equipped).
The injection ECU sends via the multiplex network Networks:
- – the set value of the regulated or limited speed on the instrument cluster;
- – a signal to turn on a constant or flashing two-color warning lamp on the instrument cluster;
- – control commands to the throttle body with a servo drive or to the diesel fuel supply regulator;
- – information about automatic transmission gear shifting (if equipped).
The injection system ECU receives information via a wired connection:
- – from the accelerator pedal position sensor;
- – from the brake light switch (has two contacts: normally open and normally closed);
- – from the clutch pedal travel sensor (if equipped);
- – signal from the three-position switch;
- – from the controls on the steering wheel wheel.
Speed Limiter
Activation conditions:
- – switch in the "speed limiter" position (30 km/h – minimum speed, 200 km/h – maximum speed);
- – pressing the "+", "–", or "R" switches.
Deactivation conditions:
- – sharply pressing the accelerator pedal (overcoming the resistance point);
- – switch in the "off" position;
- – pressing the "0" switch;
- – intervention by the injection system ECU (in case of a malfunction or exceeding the maximum permissible speed).
A flashing warning light on the instrument panel informs the driver that the set speed cannot be maintained.