Active Service System (ASSYST) Function
General
The "Active Service System" (ASSYST) draws the attention of the driver to a service which is due and indicates the service required (A/B).
ASSYST is a demand-activated engine oil service system. In other words, in addition to the pure time and distance criterion, various factors are taken into account for calculating the demand - oriented service intervals.
These are, on the one hand, quality factors, which are coded with the Star Diagnosis tool, and on the other hand weighting factors, which take into account driving conditions and thus actual wear and tear.
Under favorable conditions (small number of cold starts, driving primarily in the medium engine speed range) the service interval is longer than under unfavorable conditions.
Display
The display appears in the multifunction display (A1p13) of the instrument cluster (A1).
The service interval appears automatically as a remaining distance or remaining time in the text boxes (1, 3) together with the service symbol (2) in the multifunction display (A1p13) (Fig. 1) if requested by the driver or if the remaining distance or time drops below a warning threshold.
Engine oil monitoring
If the oil level is too low or too high, information on the oil level appears in the text boxes (1, 3) of the multifunction display (A1p13) (Fig. 2). In addition, the oil can symbol (2) appears. Moreover, the system is capable of recognizing when oil is added. If oil is added, a bonus is given which can increase the length of the service interval.
The service intervals for gasoline engines are 15 000 to 30 000 kilometers or 10 000 to 20 000 miles, and for diesel engines 20 000 to 40 000 , depending on the weighting and bonus.
Technology and influencing variables
To calculate the demand-activated service interval, ASSYST requires the values of various influencing variables, which are used for calculating the service interval and the service required (A or B).
In addition to the weighting factors which depend on real life driving conditions, quality factors are also used for calculating the demand-oriented service interval (remaining distance and remaining time).
Influencing variables
- Weighting factors (depending on reallife operating conditions):
- Load torque
- Engine speed
- Oil level
- Engine oil temperature
- Oil correction factor (serves as comparative value for determining oil level)
- Coolant temperature
The instrument cluster (A1) receives this information over the engine compartment CAN from the injection system control module (N3).
As regards the data on oil level, engine Oil temperature and oil correction factor, the injection system control module (N3) reads the data from the oil sensor (oil level, temperature and quality B40).
- Quality factors (these are factory-set to base values and can be changed with the Star Diagnosis tool, if the operating conditions of the vehicle so necessitate; they influence the start distance):
- Engine version factor (gasoline/diesel)
- National factor (The kilometer/mileage is coded according to the national version.)
- Distance travelled:
ASSYST is supplied with the signals of the four wheel speed sensors over the engine compartment CAN by the traction systems control module (N47) for calculating the distance travelled.
- Time
ASSYST receives the time information from a timer integrated in the instrument cluster (A1).
Example of service display
NOTE: Additional displays are given in other documents, particularly in the document: "Active Service System (ASSYST) driver information".
Example of engine oil display
NOTE: Additional displays are given in other documents, particularly in the document: "Active Service System (ASSYST) driver information".
NOTE: Diagnosis
Diagnosis of ASSYST is possible with the Star Diagnosis tool.
Diagnosis is started off using the instrument cluster (A1).
The diagnosis also covers the injection system control module (N3).
NOTE: Accidental actuation of oil change reset
If the oil change is reset at the instrument cluster (A1) or with the Star Diagnosis tool but the oil is not changed, this oil change reset must be cancelled immediately. An appropriate menu is available in the Star Diagnosis tool.
NOTE: Replacing instrument cluster (A1)
If it is necessary to replace the instrument cluster (A1), transfer the coding and data records to the new instrument cluster. See menu Prompting in the Star Diagnosis tool.
NOTE: Replacing oil sensor (oil level, temperature and quality, B40)
If a complaint is received after replacing the oil sensor (oil level, temperature and quality, B40) it may be necessary to perform a setting (calibration) of the oil minimum warning. This always has to be done if the message "CHECK ENGINE OIL LEVEL!" appears, but the oil level according to the dipstick is still okay. The setting is performed menu-prompted with the Star Diagnosis tool.