Electrical System Equipment & Instructions - Basic Knowledge - 211 Chassis: Maintenance Mercedes-Benz E-class W211/S211

Coolant/washer fluid level voltage coding, function - GF54.30-P-4001T

MODEL 211.0 /2 up to 31.5.06 except CODE (494) USA version except CODE (498) Japan version

MODEL 211.0 /2 up to 30.6.06 with CODE (494) USA version with CODE (498) Japan version

Coolant / Washer Fluid Level Voltage Coding - Function Diagram. Scheme 10

The coolant level indicator switch (S41) and the windshield washer fluid level indicator switch (S42) are connected in series and are read in by the driver-side SAM control unit with fuse and relay module (N10/1).

Voltage coding

Voltage coding is used in order to allow several switches to be interrogated over 2 lines. Each switch is connected in parallel with an internal resistor. The resistors (r 1 and r 2 ) of the series-connected switches (s 1 and s 2 ) have different resistances. These resistors (r 1 and r 2 ) form, with open switches (s 1 and s 2 ), together with the resistor (r 3 ) of the driver-side SAM control unit with fuse and relay module (N10/1) a voltage divider which is supplied with the constant voltage (u). Via the voltage (u e ) the driver-side SAM control unit with fuse and relay module (N10/1) can distinguish between 6 different states. As shown above, the line which leads from the resistor (r 3 ) to the driver-side SAM control unit with fuse and relay module (N10/1) serves as a reference line.

The reference line is used to determine the voltage difference between the direct line and the line running via the switches (s 1 ad s 2 ) or the resistors (r 1 and r 2 ). The two fundamental states are open circuit and short circuit. The 3rd state describes the case where both fluid levels are above the minimum mark and therefore both switches (s 1 and s 2 ) are open and the current is flowing through both resistors (r 1 and r 2 ). The 4th state describes the case where both fluid levels are below the minimum mark and therefore both switches (s 1 and s 2 ) are closed and the current is not flowing through both resistors (r 1 and r 2 ). The 5th and 6th states describe the case where one of the two fluid levels is below and the other is above the minimum mark. By means of the input voltage the driver-side SAM control unit with fuse and relay module (N10/1) detects whether the current flows through the resistor (r 1 ) or the resistor (r 2 ).

Switch status and messages

Using the coolant level indicator switch (S41) and the windshield washer fluid level indicator switch (S42) a total of the following 4 switch combination alternatives result and the consequent displays on the multifunction display (A1p13)

1. When the coolant level indicator switch (S41) is open and the windshield washer fluid level indicator switch (S42) is open, no message appears on the multifunction display (A1p13).
2. When the coolant level indicator switch (S41) is open and the windshield washer fluid level indicator switch (S42) is closed, the message "ADD WINDSHIELD WASHER FLUID" appears on the multifunction display (A1p13).
3. When the coolant level indicator switch (S41) is closed and the windshield washer fluid level indicator switch (S42) is open, the message "CHECK COOLANT LEVEL" appears on the multifunction display (A1p13).
4. When the coolant level indicator switch (S41) is closed and the windshield washer fluid level indicator switch (S42) is closed, the message "CHECK COOLANT LEVEL" and the message "ADD WINDSHIELD WASHER FLUID" appear alternatively on the multifunction display (A1p13).

Evaluation

The voltage (u e ) is applied at the input of the analog-digitale converter (ADC) of the driver-side SAM control unit with fuse and relay module (N10/1). The ADC converts the analog voltage into a digital value. The processor compares the digitized value with the threshold values stored in memory and if necessary, passes the appropriate messages "Check coolant level" and "Please refill washer fluid" on the class B (interior) controller area network bus (CAN-B). The instrument cluster (A1) reads in these messages from the CAN B and actuates the multifunction display (A1p13) accordingly.

Acknowledgment of messages (up to 31.5.05)

Warning and error messages can be acknowledged automatically or manually. Manual acknowledgment takes place by pressing the steering wheel buttons, scroll forward/back button (S110s1) and System selection button (S110s3) or the instrument illumination brightness control and reset button (A1r1). If the cause of a message which can be acknowledged is not applicable, the warning is displayed in the multifunction display (A1p13) for the duration of its minimum display time.

Acknowledgment of messages (as of 1.6.05)

The windshield washer fluid level message is displayed as of circuit status "Circuit 15C ON" and is acknowledged automatically after 5 s. Acknowledgment by pressing the steering wheel buttons scroll forward/back button (S110s1) and system selection button (S110s3) or instrument illumination brightness control and reset button (A1r1) continues to be possible.

Reset, function - GF54.50-P-2010T

MODEL 211.0 /2 up to 31.5.06

except CODE (494) USA version

except CODE (498) Japan version

MODEL 211.0 /2 up to 30.6.06

with CODE (494) USA version

with CODE (498) Japan version

Resetting the long-distance memory ("Since reset")

1. Terminal 15 ON
2. Select "After reset" display mask using system selection button (S110s3) and scroll forward/back button (S110s1) on multifunction steering wheel.
3. Hold down instrument illumination brightness control and reset button (A1r1) for one second.
4. The display is reset.

Manual reset of the short-distance memory ("Since start")

1. Circuit 15 ON
2. Select the "SINCE START" display mask (short-distance memory) using the system select pushbutton (S110s3) and the scroll forward/back pushbutton (S110s1) on the multifunction steering wheel
3. Hold down instrument illumination brightness control and reset button (A1r1) for one second.
4. The display is reset.

Automatically resetting the short-distance memory ("SINCE START") As the "SINCE START" display (short-distance memory) is considered for the data of one driving cycle, the contents of the "SINCE START" display (short-distance memory) are normally reset automatically.

If the EIS [EZS] control unit (N73) is in the "terminal 15C" position all the short-distance memory data are reset after roughly four hours. If, during this period, "terminal 15C" is interrupted by "terminal 15R ON" or "terminal 15 ON", the delete time window (four hours) is restarted

Acceptance of data from previous driving cycles into short-distance memory

In some cases it may be useful to transfer the data from the previous driving cycle into the short-distance memory, e.g. if you wish to record the data for a single tank of fuel during a vacation trip even with several breaks in the journey. The data for the entire trip can then be stored in the long-distance memory ("since reset").

The procedure for this is as follows

1. Select "After start" display mask (short-distance memory) using system selection button (S110s3) and scroll forward/back button on multifunction steering wheel.
2. Start the engine.
3. The "After start" display (short-distance memory) flashes up to 2 km/miles or 2 minutes after the engine was started.
4. While display is flashing, hold down instrument illumination brightness control and reset button (A1r1) for one second.
5. The values of the previous driving cycle are accepted into the short-distance memory

If display of the travel distance or travel time exceeds the maximum display value (40959 miles (65535 km) or 99:59 hours), then the travel time and mileage of each memory are automatically reset. This preserves the relationship between travel time and mileage

After resetting, it can take up to three miles or two minutes until the trip computer has sufficient data to display the consumption figures correctly. The national version of the instrument cluster (A1) (depending on the unit setting (kilometers/miles) and coding) is displayed during this time