bosch dishwashers open the detergent cup when the heater comes on. if you take the door panel off you will see the back of the detergent cup. if you have an amp meter, clamp the meter around the red wire coming from the control module at top. it should read 10 to 11 amps when the heater comes on. the heater comes on 10-20 minutes into the cycle. if you only have a volt ohm meter place leads into the wires on the wax motor. the wax motor is on the detergent cup. it is brown. when the heater comes on, 120 volts is sent to the wax motor and causes the plunger in the motor to move outward and open the cup. if after 25 minutes you have not gotten any voltage to the wax motor, you have a heating problem. this could be the heater or the control. most likely the control. the heater can be checked with an ohm meter, but the dishwasher has to be removed from cabinet and accessed from the right side. it is rare for a heater to go bad.