Control Board Diagnosis; Door Switch; Detergent Dispenser - Viking FDB451 Service Manual

Troubleshooting
To avoid risk of electrical shock, personal injury, or death, disconnect electrical power source to unit, unless test
procedures require power to be connected. Discharge capacitor through a resistor before attempting to service.
Ensure all ground wires are connected before certifying unit as repaired and/or operational.

Control Board Diagnosis

(Some measurements require power and others require the unit not to be powered.)
With the control board removed (see Control
Board Disassembly procedure, Page 31 ),
the following components can be diagnosed
without removal of the components:

Door Switch

The door interlock switch controls 12 VDC
to the control board. When the door is open,
the contact opens and the board stops the
operation. To check the switch, unplug the
molex connector and check for continuity
between P4-1 (red/white) and P4-2 (yellow).
With the door closed, the reading should be
0 Ω ohms. Open the door and the reading
should be infinity (∞). If the readings are
incorrect, check the wiring to the door switch
and inspect the door switch.
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! WARNING

Detergent Dispenser

The dishwasher uses a detergent dispenser
to release detergent into the tub. As voltage is
applied, the latch mechanism releases the
dispenser door allowing detergent to enter the
tub. Voltage between P4-1 and P4-4 should
be 12 VDC when the dispenser is activated. If
no voltage is measured, verify wiring.
Note: Testing the soap dispenser can be
achieved in the diagnostic mode.
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©2012 Viking Preferred Service
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