Service Manual

TESTING
18” & 24” ADA Built-In Dishwashers
n
3-11
For Service Technician Use Only
Turbidity Sensor
Overview
The turbidity sensor is located under the tub and is aached
to the sump with two snap clips (see Figure 1). During the pre-
wash cycle, the turbidity sensor senses the water and chooses
the appropriate wash cycle.
NOTE: If the turbidity sensor is not funconing, the dishwasher
will connue to operate, but choose a default wash cycle.
Turbidity
Sensor
Snap
Clips
Figure 1 - Turbidity Sensor Location
This test will check the wiring to the Turbidity Sensor, which
measures the cloudiness or haziness of the water caused by
the amount of suspended solids and parcles in the water. The
following items are part of the turbidity sensing circuit.
n Harness/Connecon
n Turbidity Sensor
n Control Board
Test Procedure
1. Check the Turbidity Sensor and electrical connecons by
performing the “Service Mode Test” on page 2-3. The
following steps assume that this step was unsuccessful.
2. Unplug dishwasher or disconnect power.
3. Remove access panel. Remove control board cover to
access control board.
4. Lay the dishwasher on its back. Use a small at-blade
screwdriver to unclip snaps around the drip-pan. Remove
drip-pan/oat switch to access under tub components.
5. Test for 5 VDC—With a voltmeter set to DC, connect the
black lead to CN4-2 (GND) and the red lead to CN3-1
(+5V).
6. Plug in dishwasher or reconnect power.
7. Measure for 5 VDC out of the control between CN4-2
(GND) and CN3-1 (+5V).
¾ If 5 VDC is measured the control is funconing, replace
the Turbidity Sensor and retest.
¾ If 5 VDC is measured, replace the control board and
retest.
8. Unplug dishwasher or disconnect power.
9. Reassemble all parts and panels.
10. Plug in dishwasher or reconnect power and run “Service
Mode Test” to verify repair.
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.
STRIP CIRCUIT - TURBIDITY SENSOR
Figure 2 - Turbidity Sensor Circuit
CONTROL BOARD
TURBIDITY SENSOR
CN3-5
TURBIDITY SENSOR
1
5V
(TURB)
CN3-6
3
(PWM)
CN3-1
2
(+5V)
BR
RD
BK
Turbidity
Optical Out