Dishwashers are durable appliances that usually offer years of trouble-free service; however, hoses can break, mechanical parts can fail, and electrical components can go bad. If your dishwasher sounds as if it’s running when you turn it on, but it won’t fill with water, one of the common causes is a bad float switch. If this happens and you own a Bosch SHY66 Dishwasher, you can access the float switch yourself after disconnecting the pump pressure chamber mechanism. Once you’ve accessed the float switch, you can run a simple continuity test to see if the switch is working properly.
Locate the circuit breaker switch supplying power to your dishwasher. Trip the switch and tape it to the panel with a strip of masking tape to prevent someone else restoring power while you’re working. Next, open the sink cabinet door and close the cold water supply shut off valve by turning the handle clockwise.
Undo the two screws securing the lower access panel to the front of the dishwasher with a Phillips head screwdriver and remove the panel. Place an absorbent cloth under the braided water supply hose connection on the left of the opening, and disconnect the hose coupling from the inlet valve with an adjustable spanner.
Use a nut driver to remove the single mounting screw securing the electrical junction box cover on the bottom right of the machine. Make a mental note of the orientation of the wires connected to the terminal block, loosen the terminal screws with a Phillips head screwdriver, and pull the wires out from under the washers.
Remove the screw securing the wire release spring bracket to the chassis and pull the bracket out. Undo the nut securing the Sprague conduit with channel pliers, and pull the conduit out of the bracket.
Undo the hose clamp on the white ribbed drain hose connected to the sink drain or garbage disposer inside the sink cabinet. Next, feed the hose through the hole on the lower right of the cabinet without pushing the end through; this will allow room to withdraw the dishwasher.
Open the dishwasher door and remove the two mounting bracket screws securing the top of the dishwasher to the cabinet or counter top. Undo the levelling leg locking screws on the bottom corners of the machine and lower the machine by turning the levelling leg adjustment nuts anticlockwise with the adjustable spanner. Next, carefully slide the machine out far enough to access both sides.
Lift the bottom of the grey felt insulating pad on the left side of the dishwasher and fold it back on top of the machine; this will expose the white nylon hose manifold attached to the top of the blue air pressure chamber.
Slide the hose manifold up and pull it out of the air pressure chamber. Lift the pressure chamber out of the base, disconnect the inlet hose by pulling it off the inlet port, and remove the red float actuator rod. Unhook the wires from the retaining clip and disconnect the wires by gripping the side of the connector with needle nose pliers and pulling it out of the float switch socket.
Pry the transparent chamber cover off with a flat head screwdriver. Press the float switch retaining clip down with the tip of the screwdriver and rotate the float switch upward to remove it.
Use a digital or analogue Multimeter to test the float switch’s continuity as follows: If you have an analogue Multimeter, select the lowest ohms of resistance setting, touch the probes together, and zero the needle all the way to the right by rotating the knurled knob on the side of the meter. If you’re using a digital Multimeter, simply select the lowest ohms of resistance setting.
Press the float switch actuator down to close the circuit. Touch the black probe to one of the switch contacts and the red probe to the other contact; if the readout shows up to 0.3 ohms of resistance, the switch is serviceable; if the readout does not respond, the switch is bad and must be replaced.
Insert a new switch if applicable or reinstall the old switch by reversing the procedure described in Step 9. Reconnect the wires by pushing the connector onto the switch and snap the cover back on to the pressure chamber.
Reconnect the water hose, align the red float switch activator and clip the pressure chamber back into the base. Test the actuator by moving it up and down to ensure that it’s free. Insert the hose manifold into the top of the pressure chamber, and press downwards until it locks into place. Next, fold the felt insulating mat back down and tuck the bottom edge behind the lip on the lower edge of the washing machine chassis.
Ensure that the end of the drain hose is still accessible from inside the sink cabinet and that the braided water supply hose and electrical wires are still in place. Once you’ve done that, carefully slide the machine back into its recess, pushing inward until the front edges behind the door are flush with the sides of the adjacent cabinets. Reach inside the sink cabinet and loop the side of the drain hose upwards so that it sits above the connection point. Next, slide the end of the hose onto the garbage disposer or sink drain outlet, and tighten the hose clamp securely.
Align the sides of the machine vertically with the cabinet edges by using the adjustable spanner to lower the levelling legs in a clockwise direction. Check that the top of the dishwasher is flush against the underside of the cabinet or counter top, and that the small gaps on either side of the machine are evenly spaced; adjust as necessary and tighten the levelling leg locking screws. Next, open the dishwasher door and replace the two upper mounting bracket screws removed earlier.
Insert the wire Sprague connector through the hole in the spring bracket, thread the nut back on and tighten it with the channel pliers. Position the bracket inside the recess and secure it with the screw removed earlier. Slide the end of the wires under their respective terminal screw washers and tighten the screws; be careful not to strip the threads by over tightening. Replace the terminal box cover and secure it with the hex head screw removed earlier.
Thread the water supply hose coupling onto the inlet valve and tighten it with the adjustable spanner. Reposition the lower front access panel, replace the mounting screws and snug them down loosely. Adjust the access panel by sliding it up or down on its elongated mounting holes so that the bottom edge just clears the floor, and tighten the screws
Turn the water supply shut off valve back on and restore the washer’s electrical power. Load the dishwasher and run a full cycle to ensure that the float switch is working properly.