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

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







The circuit on the illustration is used to determine coolant level washer the and fluid level. "a" designates the front passenger SAM control unit (N10/11).

The coolant level indicator switch (S41) and switch for level check of windshield washer system (S42) are connected in series. Both switches are read in by the front passenger SAM control unit (N10/11) via two lines.

The illustration shows the status of the switches when the washer fluid level is low.

Voltage coding
The resistances "r<>1" and "r<>2" are connected in parallel with switches "s1" and "s2" -for voltage coding (the values of "r1"and "r2" must differ.).

Together with "r<>3" from the front passenger SAM control unit, when the switches are open N10/11 these resistances form a voltage divider which is supplied with constant voltage "U const".
The voltage "U e" at the input of the front passenger SAM control unit (N10/11), is thus dependent on the positions of the switches 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 passenger SAM control unitN10/11.

Evaluation
The voltage "Ue" is applied at the input of the analog-digital-converter of the front passenger SAM control unit N10/11.

The analog-digital-converter, converts the analog voltage value into a digital value

This is necessary as the processor of the front passenger SAM control unit (N10/11) can only operate 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 left multifunction display (A1p13) for the picture and right multifunction display (A1p15) for the text.

When resistance values voltage U are known and the " U const" is known "U e" can be calculated with the following formula:

Ue=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 confirmed with the instrument lighting brightness control and reset button (A1r1) at the instrument cluster (A1).