Whirlpool Dishwasher Sump Pump Humming, Not Pumping... | appliancefaults.com

Technical Background:

The dishwasher's main control unit (MCU) sends a 120V AC signal to the drain pump relay. This relay then activates the sump pump motor, which spins an impeller to force water out through the drain hose. If the pump is blocked, the motor may only hum.

Symptoms:

The dishwasher is running, but water remains in the bottom of the tub after the cycle. You hear a humming sound coming from the sump pump area, but the water is not being pumped out.

Possible Causes:

Clogged drain hose
Blocked sump filter
Faulty sump pump motor
Obstructed impeller
Defective drain pump relay on the control board

Solution:

1

Disconnect power to the dishwasher at the breaker panel. Confirm 0V AC at the dishwasher's power receptacle with a multimeter.
2

Inspect the drain hose for kinks or clogs. Disconnect it from the garbage disposal or sink drain and check for obstructions. Clear any blockage.
3

Remove the lower spray arm and any filters covering the sump area. Check for food debris or foreign objects blocking the sump intake.
4

Access the sump pump. On many Whirlpool models, this involves removing the lower rack and a plastic housing. Disconnect the pump's wiring harness.
5

Use a multimeter to test the sump pump motor for continuity. A reading of OL (open line) indicates a faulty motor. If the motor has continuity, inspect the impeller for damage or obstructions.
6

If the motor and impeller are clear, suspect a drain pump relay failure on the main control board. Replacement of the control board may be necessary.
7

Reassemble the dishwasher, reconnect power, and test the drain cycle.

Safety Warning:

Always disconnect power to the dishwasher at the breaker before performing any repairs. Lock Out / Tag Out (LOTO) procedures are recommended to prevent accidental energization. 120V AC is present when the unit is powered.

Prevention:

Regularly clean the dishwasher's sump filter to prevent food debris from accumulating and blocking the pump. Use a dishwasher cleaner monthly.

Expert Tip:

Some Whirlpool dishwashers have a diagnostic mode. To enter it, press the following sequence within 6 seconds: High Temp, Heated Dry, High Temp, Heated Dry. This may provide error codes to help pinpoint the problem.

Frequently Asked Questions

•What is the typical lifespan of a Whirlpool dishwasher sump pump?

A typical Whirlpool dishwasher sump pump can last 5-7 years with proper maintenance. Hard water and frequent use can shorten its lifespan.

•How do I know if the drain pump relay on the control board is bad?

If the pump motor tests good and the impeller is clear, and you have verified 120V AC is reaching the control board, the relay is likely faulty. Replacing the control board is usually the only fix.

•What tools will I need to replace the sump pump?

You will likely need a 1/4-inch nut driver, a 5/16-inch socket, a pair of pliers, a flat-head screwdriver, and a multimeter. A shop towel is also recommended.

Whirlpool Dishwasher Sump Pump Humming, Not Pumping Water: Troubleshooting

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•What is the typical lifespan of a Whirlpool dishwasher sump pump?

•How do I know if the drain pump relay on the control board is bad?

•What tools will I need to replace the sump pump?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: