GF54.30-P-4001GZ Voltage Coding of Coolant/Windshield Washer Fluid Level, Function

GF54.30-P-4001GZ Voltage Coding Of Coolant/windshield Washer Fluid Level, Function

Voltage coding
For voltage coding, the switches "s1" and "s2" are connected in parallel with the resistors "r1" and "r2" (the values of "r1" and "r2" must be different).
When the switches are open, these resistors, together with "r3" of the front SAM control unit (N10), form a voltage divider which is supplied with the constant voltage "U Const".
The voltage "U e" at the input of the front SAM control unit (N10) therefore depends on the positions of the switches and the values of the resistors. With the two switches, there are therefore four possible switch combinations (see table).

Each of these combinations produces a different voltage value "U e" at the input of the front SAM control unit (N10).

Evaluation
The voltage "U e" is present at the input of the analog/digital e converter of the front SAM control unit (N10). The analog/digital converter converts the analog voltage into a digital value.
This is necessary because the processor of the front SAM control unit (N10) can only work with digital values.

The processor compares the values to the threshold values stored in memory and if necessary, relays an appropriate message (coolant and/or washer fluid level too low) over the interior CAN.
The instrument cluster (A1) reads this message and actuates the multifunction display (A1p13) for the image and text accordingly.

When the resistances and voltage "U Const" are known, "U e" can const e be calculated with the following formula:

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

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

These messages can be acknowledged by pressing the trip odometer reset button (A1s3) on the instrument cluster (A1).