Active service system (ASSYST), function - GF00.20-P-0003CW

MODEL 204.0 /2 up to Model Year 8 

Function requirements 

• Circuit 15 On

General information 

The Active Service System (ASSYST) determines each respective service date for the vehicle. They are computed and displayed in the instrument cluster (A1).

Once the service date has been reached, the display is automatically activated in the instrument cluster.

The measurement values and data filed in the read-only memory are used to compute the next scheduled service date. Both distance-related and time-related variables are taken into account.

ASSYST consists of the following subfunctions: 

• Function sequence for determining the remaining distance 
• Function sequence for determining the remaining time 
• Function sequence for service display 
• Function sequence for service reset 

Function sequence for determining the remaining distance 

The wheel speed determined by the rpm sensors (L6/1, L6/2, L6/3 and L6/4) is read in by the control unit for the Electronic Stability Program (N30/4) and sent to the chassis CAN. The instrument cluster calculates the distance covered from the values received in combination with the tire size.

Tire size is coded using STAR DIAGNOSIS.

The main odometer reading is saved continuously to the nonvolatile part of the instrument cluster's internal memory. This memory guarantees the retention of the counter reading for at least 5 years also when the voltage supply is decoupled. 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 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 instrument cluster via the chassis CAN from the ME-SFI [ME] control unit (N3/10) in gasoline engines or the CDI control unit (N3/9) for diesel engines.

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 instrument cluster.

Topping up with oil does not influence the time-based servicing scheme.

Function sequence for service display 

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 off to the nearest 5 days. The service interval can also be displayed as the remaining distance in the multifunction display (A1p13) in response to a driver request or automatically when a value exceeds a warning threshold.

Function sequence for service reset 

The left multifunction steering wheel button group (S110) and right multifunction steering wheel button group (S111) can be used to reset the service. This is shown in the multifunction display.

The multifunction steering wheel button groups are read in over the steering LIN by the steering column module control unit (N80). The signals are then forwarded over the chassis CAN to the instrument cluster.

	Active Service System (ASSYST), location of components		GF00.20-P-0003-08CW
	Active Service System (ASSYST), block diagram		GF00.20-P-0003-03CW
	Instrument cluster, component description	A1 Without code (442) Comfort multifunction steering wheel	GF54.30-P-6000CWA
		With code (442) Comfort multifunction steering wheel	GF54.30-P-6000CWB
	Component description for the rpm sensor	L6/1, L6/2, L6/3, L6/4	GF42.30-P-4552CW
	Electronic Stability Program control unit component description	N30/4	GF42.45-P-5119CW
	Electronic ignition switch control unit, component description	N73	GF80.57-P-6001CW
	Steering column module control unit, component description	N80	GF54.21-P-6051CW