Automatic Start/Stop Of Engine [2014-2016, B4204T11, TG-81SC]: Function: Conditions

Basic conditions: 

The basic conditions for the automatic start/stop of the engine function to be activated are:

• The outside temperature is within certain limit values. These limit values differ between different engine variants and markets. Normally, start/stop is activated between approx. 0 °C - +30 °C.
• The engine is at normal operating temperature.
• The engine compartment temperature is normal.
• The battery (main battery) is charged.
• The battery (main battery) temperature is between 0 °C - +55 °C. In the event of temperature changes, the battery's (main battery) temperature changes more slowly than the outdoor temperature. If the outdoor temperature has been below 0 °C for a long time and then rises above 0 °C the battery's (main battery) temperature takes longer to reach 0 °C. Even at fixed outdoor temperatures above 0 °C the battery temperature can be too low to permit the automatic start/stop of the engine function. This also applies to high temperatures, where the battery's (main battery) sluggishness follows the outdoor temperature. The battery's (main battery) temperature is calculated by the battery monitoring module.
• The battery monitoring sensor has calculated the battery's (main battery) status correctly (calculation reliable).
• The secondary battery is charged (normal pole voltage).
• Secondary battery's average voltage at previous autostop was above 10.4 V.
• Mixed control modules in the vehicle have not detected any faults (stored DTCs) on component parts or systems for automatic start/stop of engine.
• No risk of mist on the windscreen.
• Vehicle is set to normal mode (not transport mode).
• The vacuum (air pressure) in the brake amplifier is normal.
• The heating or cooling demand in the passenger compartment is too great.
• Regeneration of soot particles are not activated (diesel only).

For descriptions of reasons for blocking of autostop, See VIDA - INFORMATION/SPECIFICATIONS/SPECIFICATION, MISC.

Conditions that can be affected by the driver: 

• The driver has the safety belt on.
• The driver's door is closed.
• The climate control system fan must not be too fast (too high current). This means that the defroster must not be manually activated. In this position the blower fan runs too fast. This also applies to the AUTO function (automatic heating control). If it is colder or hotter in the passenger compartment in relation to the selected temperature, the blower fan runs too fast.
• The vehicle must be completely stationary.
• Gear lever in neutral position (only vehicles with manual gearbox).
• The clutch pedal completely released (only vehicles with manual gearbox).
• If reverse is engaged, the function is not permitted. After the vehicle has reversed, it must be driven forwards at a speed above 5 km/h before the function is activated. This enables the car to be parked between two other cars without the engine auto-stopping.

System requested restart of engine 

An engine in autostop can, in certain instances, restart without request from the driver (system requested restart of the engine). System requested restart can only occur with the gear lever in neutral. If the gear lever is not in neutral the driver is asked to engage the gear lever in neutral via a text message in the Driver information module (DIM).

The following events can automatically restart the engine in autostop:

• Current or power consumption in the vehicle is too high, e.g. if many power consumers in the vehicle are switched on.
• The engine's or the automatic gearbox's operating temperature is too high or low.
• The battery's (main battery) state of charge (SoC) drops too low.
• The battery's (main battery) voltage drops too low.
• The battery's (main battery) temperature falls below or exceeds 0 - +55 °C.
• The battery monitoring sensor has not calculated the battery's (main battery) status correctly (calculation is no longer reliable).
• The secondary battery voltage drops too low.
• Repeatedly pump the brake pedal so that the vacuum in the brake amplifier is reduced.
• Mixed control modules in the vehicle have detected faults (stored DTCs) on component parts or systems for automatic start/stop.
• In the event of risk of mist on the windscreen, the Climate Control Module (CCM) can request a start of the engine.
• The climate control system fan runs too fast (too high current).
• The cooling requirement in the passenger compartment is too great.
• The vehicle starts to roll at a speed above 4 km/h.
• The driver depresses the accelerator pedal.

For descriptions of reasons for system requested autostart, See VIDA - INFORMATION/SPECIFICATIONS/SPECIFICATION, MISC.

An engine in autostop can, in some instances, block autostart. To start the engine, the key must be used.

The following events can block autostart:

• The driver's safety belt has been undone.
• A gear has been engaged without the clutch pedal being depressed (released).
• A fault has been detected that makes a safe autostart impossible. This can, for example, be due to a fault on the internal power supply from the Engine Control Module (ECM) to different components.