Filter
Top Products
– 23 –
Turbidity Sensor
The turbidity sensor is located on the side of the
sump.
The turbidity sensor measures the amount of
suspended particles in the wash water in the sump.
The control sends the turbidity sensor a pulse width
modulated 5-volt signal for calibration and usage
during operation.
The control then receives an analog signal of
the sensed turbidity, which is processed by the
microprocessor.
The baseline reading is taken during the fi rst fi ll
when the sump water level is between the
1
/
4
- to
3
/
8
-in. gap between the LED transmitter and the
receptor. Successive tur bid i ty mea sure ments
are sup plied to the control module and used to
de ter mine whether any prewash or rinse cycles can
be skipped. The sensing LED is on during all prewash
cycles and during the fi nal rinse.
Decisions are based on a com par i son of clean
water mea sure ments at the beginning of the fi rst
fi ll, mea sure ments taken at selected fi lls, and water
tem per a ture. By measuring the turbidity level, the
control module can conserve energy on lightly
soiled loads by skipping un nec es sary cycles.
Note: If the turbidity sensor circuit fails to open or
is shorted, the sensing LED on the control panel will
not light, and the unit will operate for the maximum
amount of time, using the maximum number of
wash and rinse fi lls for the selected cycle.
The turbidity sensor also contains the thermistor
for automatic temperature controlTurbidity Sensor
Test
Turbidity Sensor
Key
The thermistor’s resistance has a negative
temperature coeffi cient. As the temperature
increases, the resistance goes down. At 75°F, the
resistance is approximately 9.9K Ω. At 140°F, the
resistance is approximately 2.8K Ω.
Note: When installing the turbidity sensor, align the
key on the sensor with the keyway on the sump.
The Service Mode is the most accurate way to test
the turbidity sensor circuit. The turbidity sensor
circuit con tains the control module, wiring, and the
tur bid i ty sensor.
Turbidity Sensor Strip Circuit
Calibrating the Turbidity Sensor
When replacing the turbidity sensor, or if it has been
disconnected, always calibrate the turbidity sensor
to the control board.
Note: The calibration cycle MUST be entered within
2 minutes of power up.
Press the Normal pad (the up arrow pad on Top
Control Models) and the Cookware pad (the down
arrow pad on Top Control Models) for 3 seconds or
until all LEDs turn on.
The dishwasher will then perform a series of steps.
Once the drain cycle starts, calibration is complete
and the Start/Reset pad can be pressed to end the
calibration cycle. The dishwasher will continue to
pump out remaining water and cycle of.
NTC
1
2
3
4
YELLOW/BLK
DK. BLUE
GRAY
ORANGE