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Pressure Switch
The pressure switch is mounted to front of the sump, located in the lower base area. A small hose
connects the pressure switch to the sump, allowing the switch to sense water levels inside the
sump assembly. This NO switch will close and complete the circuit when the water level in the sump
reaches 2.5” This is a non adjustable level, do not attempt to change. If a “Drain” fault occurs, the
Control board has detected a closed circuit on pins 1 & 3 of terminal P12, when it should be open,
indicating that water is still present in the sump, after the unit has attempted two drain events with
no success.
If water is present see drain pump section for diagnosis.
If the tank is empty, a fault could exist with the pressure switch. It could be stuck in the closed
position, or clogged under pressure. Check the connecting hose, sump port and switch body for ob-
structions. If no obstruction is found; examine the switch for proper operation. If found to be faulty
- replace.
Wash Process Sensor
The wash process sensor, WPS, is mounted to the front of the sump mounted in the base area. The
WPS consists of a transparent plastic cover in which an optical transmitter and receiver are housed.
A beam of light passes through the soiled water and is picked up by the receiver. The difference
between the light transmitted and the light received estimates the amount of soil in the water. In
normal mode, wash times are modied based on the soil levels determined by the WPS.
In addition to water soil level, the WPS detects the wash water temperature, and is used by the
control board, to regulate the inline heater on time.
If the WPS sensor is suspect, enter the Factory Test Mode. If an F4 or an F9 failure is detected then
either the WPS or the wiring has failed. Remove the wire connector from P10 on the power board,
and check for resistance as follows: Between red & yellow points on the connector it should read
14.0 – 16.0 ohms. Between the Red and Orange points on the connector it should read 10.0 – 13.0
ohms. If the measured values are outside of these tolerances, then replace the WPS sensor, and
perform the Factory Test (page 68) again.
If no values are detected, remove the small, 3 pin connector from the WPS and check resistance
from the left pin to the right pin and you should read 14.0 –16.0 ohms. Then check between the
left pin to the middle pin and you should read 10.0 – 13.0 ohms. If both values are found to be in
tolerance, check the wiring for faults. If one or both of the readings are out of tolerance then re-
place the WPS and perform the Factory Test (page 68) again.
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