Whirlpool M-17 Technical Manual page 51

DANGER
Electrical Shock Hazard
Only authorized technicians should perform
diagnostic voltage measurements.
After performing voltage measurements,
disconnect power before servicing.
Failure to follow these instructions can result in
death or electrical shock.
Water Sensing with the OWI Sensor
This test will check the wiring to the OWI (Optical Water
Indicator), which incorporates the temperature thermistor and
the foam and turbidity sensor. The following items are part of the
water sensing circuit:
n Harness/Connection
n OWI Sensor
n Control Board
Test Procedure
1. Check the operation of the OWI Sensor in the Service
Diagnostics Cycle.
2. Unplug dishwasher or disconnect power.
3. Remove toe and access panels to access control board.
4. Disconnect P10 from the Control Board.
5. Using an ohmmeter, measure resistance between P10, pins
1 and 3. The following table provides approximate room
and hot water temperatures and their associated resistance
values.
Temp °C (°F)
20 (68)
25 (77)
30 (86)
35 (95)
Strip Circuit - Water Sensing
Electronic
Control
For Service Technician Use Only
RES Range kΩ (ohms)
57.3 - 60.3
45.9 - 48.1
37.0 - 38.7
30.1 - 31.3
Pin 1
YL
P10-6
YL
Pin 2
P10-5
YL Pin 3
P10-4
Pin 4
YL
P10-3
Pin 5
YL
P10-2
Pin 6
YL
P10-1
Whirlpool and KitchenAid
®
Temp °C (°F)
40 (104)
45 (113)
50 (122)
55 (131)
60 (140)
65 (149)
70 (158)
NOTE: All thermistor resistance measurements must be made
while dishwasher is unplugged or disconnected from power and
connector P10 removed from control.
¾ If the thermistor resistance is OK , the thermistor is good.
Go to step 6.
¾ If the thermistor resistance does not agree with the table,
replace the OWI Sensor.
¾ If an open circuit is detected, check connections and
harness continuity between control and OWI. If good,
replace the OWI Sensor.
6. Using an ohmmeter, check P10 -1 to cabinet ground and
P10-3 to cabinet ground.
¾ If no short is indicated, go to step 7.
¾ If either pin indicates continuity to ground (short), repair
or replace wiring harness and retest.
7. Reconnect P10 to control board.
8. Test for 5 VDC with a voltmeter set to DC, connect the black
lead to P10-2 and the red lead to P10-3.
9. Plug in dishwasher or reconnect power.
10. Start the Diagnostics Cycle and at the proper interval
measure for 5 VDC out of the control board between P10-2
and P10-3.
¾ If 5 VDC is measured the control is functioning, go to
step 11.
¾ If no DC voltage is measured, replace the control board
and retest.
11. Unplug dishwasher or disconnect power.
12. Reassemble all parts and panels.
13. Plug in dishwasher or reconnect power and run Diagnostics
Cycle to verify repair.
Turbidity Drive
OWI Sensor
Unused
OPT Sig
VCC
Temperature: NTC Thermistor
Ref
45.9 KΩ - 48.1 KΩ at 77°F (25°C)
11.6 KΩ - 11.8 KΩ at 140°F (60°C)
NTC
Measure NTC resistance at P10-1 and
P10-3 connector disconnected from control.
Filtration and Maytag
® ®
COMPONENT TESTING (Cont.)
RES Range kΩ (ohms)
24.6 - 25.4
20.2 - 20.8
16.7 - 17.1
13.9 - 14.2
11.6 - 11.8
9.7 - 9.9
8.2 - 8.4
24" Microfiltration Dishwashers 3-13
n