Troubleshooting - Bosch SHE55P Repair Manual

6.2

Troubleshooting

6.2.1 Heater diagnosing
Test programs heat the water to 150ºF at ~ 2ºF / minute. To
save time, don't run the entire test – when water circulates and
the heater is on, measure the incoming current to the dishwasher.
If the current is ~ 11A, the heater is OK. If the current is ~ 1.5 –
2A, the control or heater could be faulty.
At the control or heater, measure the voltage between the large
red heater wire and a chassis ground or the dw neutral (WHRD
on/off switch or flow switch wire). If the voltage is 120 VAC, the
control is OK. If the voltage is 0, the heater relay has failed –
replace the control.
To check the heater, turn off the dishwasher, block up the tank
and check the resistance of each part of the heater as follows.
TIP: Current can be measured through the
control or heater (~ 9.5A). There can be more than one red wire,
so check the wiring diagram to select the heater wire.
NOTE: Open door to run test program for fully-integrated models.
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 Heater ~ 11 Ω
 Hi-Limit ~ .3 Ω
 Flow switch ~ .4Ω. A spring
loaded plunger closes it when water
is flowing, so you must remove the
microswitch from the heater and
close its contacts to measure the
resistance.
red heater wire at the
6.2.2 Controls timing out and showing "1"
Occasionally dishwashers can run for hours, not finish washing &
show a "1" in the display. This means the module has timed out
due to an unidentified heating problem -- all heating related parts
must be checked until the problem is found.
Heating system checklist if controls time out:
 Check control module heater relay & solder joints.
 Check wire harness & terminals (to control and heater).
Controls have been replaced when the problem was loose
connections.
 Check heater resistance (~ 11).
 Check flow switch (~ 0.4). If flow switch is OK & water
doesn't flow, check circulation pump.
 Check NTC (~ 55k @72ºF) and Hi-Limit.
resistance chart (section 6.3.3).
IMPORTANT: Whenever a "1" shows in the control display, reset
the control after fixing the heating problem by running the
dishwasher. The module resets after the 1st run.
Flow
switch
See NTC
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