Sprinter 3500 L5-2.7L DSL Turbo (2004)
Maintenance Required Lamp/Indicator: Description and Operation
MAINTENANCE INDICATOR
DESCRIPTION
An Active Service System (ASSYST) engine oil maintenance indicator is optional equipment on all instrument clusters. In vehicles so equipped, a
second, dedicated ASSYST microprocessor is integral to the cluster electronic circuit board. The ASSYST indications are displayed and can be toggled
with the clock indication on the right side of the multi-function indicator Liquid Crystal Display (LCD) located near the lower edge of the instrument
cluster, directly below the speedometer. The ASSYST displays include numeric values combined with several icons to indicate actual engine oil level,
and reminders in time (days) or distance (miles or kilometers) until the next required engine oil maintenance is anticipated. ASSYST also provides
several audible indications using the electronic tone generator on the instrument cluster circuit board to supplement these visual displays.
The indications of the ASSYST engine oil maintenance indicator are not visible when the LCD is not illuminated. When illuminated, the ASSYST
indications appear as dark characters and icons silhouetted against an amber field. When the exterior lighting is turned Off, the display is illuminated at
maximum brightness. When the exterior lighting is turned On, the display illumination level can be adjusted in concert with the cluster general
illumination lighting using the "+" (plus) and "-" (minus) multi-function indicator push buttons. The ASSYST engine oil maintenance indicator is
serviced as a unit with the instrument cluster.
OPERATION
The ASSYST engine oil maintenance indicator microprocessor uses numerous criteria besides time and mileage to evaluate vehicle maintenance
requirements. Time data is taken from the electronic digital clock integral to the instrument cluster. Vehicle distance data is obtained from the Controller
Antilock Brake (CAB) over the Controller Area Network (CAN) data bus. Coolant temperature, engine oil temperature, engine oil level, engine oil
quality, engine speed, and engine load data are obtained from the Engine Control Module (ECM) over the CAN data bus. Using all of the available data
and internal programming, the ASSYST microprocessor then calculates the estimated time and distance to the next required engine oil maintenance
interval. The ASSYST uses the multi-function indicator LCD to display that data and, when necessary, issues audible alerts to the vehicle operator
through the electronic tone generator on the cluster circuit board.
See the owner's manual in the vehicle glove box for the features, use, operation and resetting procedures for the ASSYST maintenance computer. Proper
diagnosis and testing of the ASSYST engine oil maintenance computer, the CAN data bus and the electronic data bus message inputs to the EMIC that
are used by the ASSYST computer for its calculations requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
