Moisture Sensor; Wash Diverter; Water Temperature Sensor - Viking VDB325 Service Manual

Service Diagnostics and Procedures
Control Board Diagnosis (continued)
(Some measurements require power and others require the unit not to be powered.)

Wash Diverter

The dishwasher uses a wash diverter to divert water
to either the upper arm or lower arm during the
wash cycle. This allows for low water consumption
and a better wash to both upper and lower racks.
At the beginning of each wash cycle, the control
board positions the wash diverter to its proper
starting position. It is monitored by a built in
monitoring switch that sends 120 VAC back to
P6-5 (yellow). Depending on how long the switch is
closed determines what position it is in.
To check the wash diverter, check the motor with an
ohmmeter between P6-2 (gray) and Neutral. It should
read approximately 2.7k
incorrect, verify wiring connections to the diverter. If
the wiring is proper, replace the wash diverter (see
Wash Diverter Disassembly procedure, page 42).
P6-2
Neutral
Wash Diverter
Note: If the diverter does not position itself, a
diverter time out error will display
(see Fail Codes, page 16-18).
© 2011 Viking Preferred Service
ohms. If readings are
To Motor
To Switch
P-6
Main Control Board

Moisture Sensor

The dishwasher uses a moisture sensor that is
mounted in the base pan of the dishwasher. Any
moisture that comes in contact with the sensor
will cause the unit to stop filling, operate the drain
pump, and signal an error code. If the sensor is
open, an open fail code will signal (see Fail Codes,
page 16-18). Resistance between P8-1 and P8-2
should be 175K ohms.
Moisture Sensor

Water Temperature Sensor

The dishwasher uses a water temperature sensor
that is mounted in the sump of the dishwasher. It is
an N.T.C (Negative Temperature Coefficient). As
the temp of the water rises, the resistance drops
(and vice-versa).
The control board monitors P8-3 – P8-4. Resistance
should be 47K
check wiring. If wiring is OK, replacement of the
sensor is necessary.
Water Temperature
Sensor
P-8
Main Control Board
P-8
Main Control Board
24