Active service system (ASSYST PLUS), function - GF00.20-P-0004LE
MODEL 216.3, 221.0 /1 as of model year 09/YoM 08
General function requirements
- Circuit 15 On
The circuit 15 status is sent by the EIS [EZS] control unit (N73) to the chassis CAN and forwarded by the central gateway control unit (N93) over the central CAN to the instrument cluster (A1).
Active Service System (ASSYST PLUS), general information
The ASSYST PLUS system calculates when the vehicle is due for a service.
This is computed and displayed in the instrument cluster.
When the service is due, the display is automatically activated on the instrument cluster.
The ASSYST PLUS system consists of the following component functions:
- Function sequence for determining the remaining distance
- Function sequence for determining the remaining time
- Function sequence for evaluating data
- Function sequence for service display
- Function sequence for service reset
Function sequence for determining the remaining distance
The remaining distance component function is determined using the following subfunctions:
- Determining the mileage
- Weighting the mileage
Determining the mileage
The warning threshold for the remaining distance is primarily decisive for the service warning if the remaining distance reaches the service warning threshold before the remaining time. The service warning threshold is filed in the central gateway control unit' internal maintenance computer.
In order to determine the remaining distance, the left front RPM sensor (L6/1), right front RPM sensor (L6/2), left rear RPM sensor (L6/3) and right rear RPM sensor (L6/4) signals are read in by the ESP control unit (N47-5) and sent to the chassis CAN. The central gateway control unit forwards them over the central CAN to the instrument cluster.
The instrument cluster uses the signals from the RPM sensors to calculate the distance traveled and sends this value over the central CAN to the central gateway control unit's maintenance computer. The remaining distance to the next service is determined by the counter-check with the travel distance reading stored at the last service.
Tire size is coded using STAR DIAGNOSIS. The main odometer reading is continually stored in the nonvolatile memory of the instrument cluster. This memory guarantees the retention of the counter reading for at least five years even when the voltage supply is decoupled.
Weighting the mileage
The following driving conditions are taken into account for the weighting of the mileage:
- Number of cold starts
- Short-distance trips
- Engine speeds
- Engine temperature
- Engine oil pressure
The remaining distance and thus also the maintenance interval can be extended or shortened by the mileage weighting. The process also takes into account whether the vehicle is actually being driven or whether the engine is being operated at idle.
The actual driving conditions are sent by the CDI control unit (N3/9) (with diesel engine) or by the ME-SFI [ME] control unit (N3/10) (with gasoline engine) over the chassis CAN to the central gateway control unit. The relevant data are then evaluated in the internal maintenance computer.
Only 0.6 km are calculated for each kilometer traveled in accordance with the relevant driving conditions.
In the worst evaluation however each kilometer driven can also be counted with 3.0 km.
The weighting of the mileage has no influence on the display of the maintenance interval or the remaining distance.
The evaluation only runs in the background and can be read out using STAR DIAGNOSIS. Depending on the national coding, the central gateway control unit's maintenance computer contains a fixed maintenance interval of s = 8000 km, 10, 000 km, 15, 000 km, 20, 000 km, 25, 000 km or one year.
Function sequence for determining the remaining time
If the mileage reading is low, it is necessary to ensure that the maximum permissible time between two maintenance intervals is not exceeded. To this end, the times since the last service are determined and then saved. Information on the engine running characteristics is made available to the central gateway control unit's maintenance computer by the CDI control unit or the ME-SFI [ME] control unit over the chassis CAN.
Times in which the on-board electrical system battery (G1) was disconnected are unable to be recorded. The maximum permissible time to the next service date is filed in the maintenance monitor. The following variables are sent by the CDI control unit or the ME- SFI [ME] control unit to the chassis CAN:
- Engine oil level
- Engine temperature
- Engine speed
- Engine torque
- Engine off time (for engine 275, 629 only)
The engine oil level on model 216 with engine 272, 273 and for model 221 with engine 272, 273, 642 is recorded by the oil level check switch (S43). On model 216 with engine 275 and on model 221 with engine 275, 629, the engine oil level is recorded by the oil sensor (oil level, temperature and quality) (B40).
The engine temperature is defined by the coolant temperature, which is recorded by the coolant temperature sensor (B11/4). The engine speed for vehicles with engine 156, 272, 273, 629 and 642 is determined by the crankshaft Hall sensor (B70) and for vehicles with engine 275 by the crankshaft position sensor (L5). This information is read in by the CDI control unit or from the ME-SFI [ME] control unit and sent by the central gateway control unit to the chassis CAN.
Function sequence, evaluation of data
Apart from the evaluation factors which depend on the real driving conditions, quality factors for determining the service scope and intervals are taken into account by ASSYST PLUS.
A comparison with the distance reading saved during the last service (Reset service) enables the remaining distance to the next service date to be calculated.
Function sequence for service display
The following information with service code is shown in the multifunction display (A1p13) of the instrument cluster:
- Service XX in XX days
- Service XX in XXXX km or miles
- Carry out service XX
- Service XX overdue by XX days
- Service XX overdue by XXXX km or miles
The remaining distance and remaining time values shown in the displays (service menu, display and warning) do not show the exact driven distance or day, but rather they are rounded off. The remaining distance is rounded up or down to the nearest 100 km. The remaining time is rounded up to five days.
The service interval can also be displayed in the multifunction display upon driver request or automatically as the remaining distance when a value exceeds a warning threshold.
Function sequence for service reset
The service can be reset in the instrument cluster's workshop level by pressing the left multifunction steering wheel button group (S110) and the right multifunction steering wheel button group (S111).
The multifunction steering wheel button group signals are read in over the steering LIN by the steering column tube module (N80) and sent to the chassis CAN.
The central gateway control unit makes them available to the instrument cluster on the central CAN.
| Active Service System (ASSYST PLUS), location of components | GF00.20-P-0004-03LE | |
| Active Service System (ASSYST PLUS), block diagram | GF00.20-P-0004-05LE | |
| Instrument cluster, component description | A1 | GF54.30-P-6000LE |
| ME-SFI [ME] control unit, component description | N3/10 On engine 156 |
GF07.61-P-6000MAS |
| ESP control unit, component description | N47-5 | GF42.45-P-5118LE |
| EIS [EZS] control unit, component description | N73 | GF80.57-P-6003LE |
| Steering column tube module, component description | N80 | GF54.21-P-6050LE |
| Central gateway control unit, component description | N93 | GF54.21-P-4170LE |