Shut off the electrical power to the dishwasher circuit at the service panel. Also, turn off the water supply at the shutoff valve, usually located directly under the floor.
Disconnect the old plumbing connections. First unscrew the front access panel. Once the access panel is removed, disconnect the water supply line from the L-fitting on the bottom of the unit. This is usually a brass compression fitting, so just turning the compression nut counterclockwise with an adjustable wrench should do the trick. Use a bowl to catch any water that might leak out when the nut is removed.
Disconnect the old wiring connections. The dishwasher has an integral electrical box at the front of the unit where the power cable is attached to the dishwasher’s fixture wires. Take off the box cover and remove the wire connectors that join the wires together.
Disconnect the discharge hose, which is usually connected to the dishwasher port on the side of the garbage disposer. To remove it, loosen the screw on the hose clamp and pull it off. You may need to push this hose back through a hole in the cabinet wall and into the dishwasher compartment so it won’t get caught when you pull the dishwasher out.
Detach the unit from the surrounding cabinets. Remove the screws that hold the brackets to the underside of the countertop. Then put a piece of cardboard or old carpet under the front legs to protect the floor from getting scratched, and pull the dishwasher out.
Prepare the new dishwasher. Tip it on its back and attach the new L-fitting into the threaded port on the solenoid. Apply some Teflon tape or pipe sealant to the fitting threads before tightening it in place to prevent possible leaks.
Attach a length of new automotive heater hose, usually 5/8" diameter, to the end of the dishwasher’s discharge hose nipple with a hose clamp. The new hose you are adding should be long enough to reach from the discharge nipple to the port on the side of the kitchen sink garbage disposer.
Prepare for the wiring connections. Like the old dishwasher, the new one will have an integral electrical box for making the wiring connections. To gain access to the box, remove the box cover. Then install a cable connector on the back of the box and bring the power cable from the service panel through this connector. Power should be shut off at the main service panel at all times.
Install a leveling leg at each of the four corners while the new dishwasher is still on its back. Just turn the legs into the threaded holes designed for them. Leave about 1/2" of each leg projecting from the bottom of the unit. These will have to be adjusted later to level the appliance. Tip the appliance up onto the feet and slide it into the opening. Check for level in both directions and adjust the feet as required.
Once the dishwasher is level, attach the brackets to the underside of the countertop to keep the appliance from moving. Then pull the discharge hose into the sink cabinet and install it so there’s a loop that is attached with a bracket to the underside of the countertop. This loop prevents waste water from flowing from the disposer back into the dishwasher.
Lengthening a Discharge Hose 
If the discharge hose has to be modified to fit onto the disposer port, first insert a 4"-long piece of 1/2" copper tubing into the hose and hold it in place with a hose clamp. This provides a nipple for the rubber adapter that fits onto the disposer.
Clamp the rubber disposer adapter to the end of the copper tubing nipple. Then tighten the hose clamp securely.
Push the adapter over the disposer’s discharge nipple and tighten it in place with a hose clamp. If you don’t have a disposer, this discharge hose can be clamped directly to a modified sink tailpiece that’s installed below a standard sink strainer.
Adjust the L-fitting on the dishwasher’s water inlet valve until it points directly toward the water supply tubing. Lubricate the threads slightly with a drop of dishwashing liquid and tighten the tubing’s compression nut onto the fitting. Use an adjustable wrench and turn the nut clockwise.
Complete the electrical connections by tightening the connector’s clamp on the cable and then joining the power wires to the fixture wires with wire connectors. Attach the ground wire (or wires) to the grounding screw on the box, and replace the cover.
Install the access panel, usually by hooking it on a couple of prongs just below the dishwasher’s door. Install the screws (if any) that hold it in place, and turn on the water and power supplies. Replace the toe-kick panel at the bottom of the dishwasher.
