Wash/Rinse Motor - Maytag MDB series Service Manual

TESTING
DANGER
(Top)
W2
P5
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.
-2 -1 -1

Wash/Rinse Motor

P5
P4
This test will check the wiring to the wash/rinse motor and the
motor itself. The following items are part of the wash/rinse
motor circuit.
n Harness/Connection
n Wash/Rinse Motor & Capacitor
n Control Board
Test Procedure
1. Check the tub and sump for anything that may be
impeding water flow. Inspect and if necessary clean the
coarse-filter system. Also, inspect spray arm water nozzles
and clean if needed.
2. Check the wash/rinse motor and electrical connections
by performing the Service Diagnostic Cycle. The following
steps assume that this step was unsuccessful.
3. Unplug dishwasher or disconnect power.
13V
N.O.
4. Remove outer door panel to access control board.
V V
P9-6 P9-5
5. Unplug connector P5 from control board.
Door
Switch
P10-4
Electronic Control
Strip Circuit – Wash/Rinse
Motor Power
L1
BK
3-12 Maytag Chopper Dishwashers
n
Control Pinout
For Service Technician Use Only
P6
-9 -1
-6
P7
P6
BR
BU
Dishwasher Strip Circuits
(To Heater)
N.O.
Door
K1
Switch
Heater (N) Relay
Sensing
Input
Ref
N.O.
P4-2
K2
Pilot L1 Relay
(Also see Door
Switch Circuit)
Electronic Control
Ω of F9 Triac Fuse
6. Check the wash/rinse motor—using an ohmmeter,
measure the resistance between P5-1 and P5-2.
¾ If the resistance is between 10-15 ohms, the wash/
rinse motor and harness are good. Go to step 7.
¾ If outside the range, replace the wash/rinse motor.
¾ If an open circuit is detected, check connections and
P7
harness continuity between control and wash/rinse
P8 P9
motor. If good, replace the motor.
7. Reconnect P5 to control board.
8. Set voltmeter to AC and connect leads to test-pads
P5-1 & P5-2 on the control board. Plug in dishwasher or
reconnect power.
9. Start the Diagnostic Cycle and at the proper interval
measure for AC out of the control between P5-1 & P5-2.
(Refer to Wash Motor Strip Circuit below.)
¾ If no AC voltage is measured, replace the control board
-6 -1
-6 -1 -5 -6
and retest.
¾ If 120 VAC is measured and wash/rinse motor is
P8 P9
running, go to step 12.
RD V
¾ If 120 VAC is measured and wash/rinse motor is not
running, go to step 10.
10. Test the wash/rinse motor capacitor. NOTE: A faulty
capacitor may cause the motor to "hum," not start, or
Unplug dishwasher or disconnect power.
I
start slowly.
Perform resistance checks. To check resistance of a comp
a. Discharge the capacitor by touching the leads of a
I
disconnect harness leads first. 20,000 Ω resistor to the two terminals.
b. Disconnect the wires from the capacitor terminals.
c. With an ohmmeter, measure across the terminals and
note reading.
(To Wash Motor,
¾ If a steady increase in resistance is noted, capacitor is
Vent, and Triac Loads)
good. Replace wash motor assembly and retest.
¾ If the capacitor is either shorted or open, replace
N.O.
capacitor. and retest.
K2
11. If the preceding steps did not correct the wash/rinse
Pilot (L1) Relay
motor problem, replace the control board.
12. Unplug dishwasher or disconnect power.
13. Reassemble all parts and panels.
14. Plug in dishwasher or reconnect power and run Diagnostic
Micro Pin Micro Pin
Cycle to verify repair.
Electronic Control
Run
Winding
3Ω - Ω
TURQ
(LBU)
V
P5-2
Pin 1
AUX
YL
Winding
6Ω - 1 Ω
Motor and Capacitor
Wash Pump)
120V, 60 Hz, 250 W
N
P10 P11
-1 -3 -5 -1 -2 -4 -6
P10 P11
BR RD
(To Wash Motor)
(To Heater)
N.O.
K3
Motor (N) Relay
Heater (L1) Relay
Micro Pin
Sense Resistor
or Jumper
TURQ
(LBU)
N.O.
P5-1
K4
Pin 3
Motor N Relay
CAP
YL
(Also see Door
23.5 µF
Switch Circuit)
Electronic Control
YL Pin 1
P12
P13
(OWI)
P12 (Wide Out)
P13
-1 -3
P12
YL
N.O.
K4
Micro Pin
N
0Ω
WH
P4-1
Turbidity Drive