GF54.30-P-4001RT Coolant/Washer Fluid Level Voltage Coding, Function

GF54.30-P-4001RT Coolant/washer Fluid Level Voltage Coding, Function

Voltage coding
For voltage coding the switches "s1" and "s2" are connected in parallel with the resistances "r1" and "r2" (the values of "r1" and "r2" must differ).

When the switches are open, together with "r " of the front SAM 3 control unit (N10), these resistors form a voltage divider which is supplied with the constant voltage "U const".
The voltage "U e" at the inlet of the front SAM control unit is e therefore dependent on the positions of the switches and the values of the resistances.
With the two switches, there are therefore four possible switch combinations (see table).

Each of these combinations results in a different voltage value "U e" at the input of the front SAM control unit.

Evaluation
The voltage "U e" is applied at the input of the Analog-Digital e converter of the front SAM control unit. The analog/digital converter converts the analog voltage into a digital value. This is necessary as the processor of the front SAM control unit can only work with digital values.

The processor compares the incoming values with the threshold values stored in the memory and, as need be, outputs the corresponding message (coolant level and/or washer fluid level too low) over the interior compartment CAN. The instrument cluster (A1) reads this message and actuates the multifunction display (A1p13) for the picture and text accordingly.

With known resistance values and a known voltage "U Const", "U e" can be calculated with the following formula:

U e = U (const X (r1+r2)/(r1+r2+r3)

The following table shows the warning messages which appear according to the status of the switches.

These messages can be acknowledged with the trip odometer reset button (A1s3) on the instrument cluster.