GE Dishwasher Error Code 999: Troubleshooting Draining... | appliancefaults.com

Technical Background:

The GE dishwasher's Main Control Unit (MCU) monitors various sensors, including the water level sensor and float switch, to manage the wash cycle. The MCU controls the drain pump's activation. A fault in the sensor input or the MCU itself can lead to unintended drain pump activation. Voltage is typically 120V AC to the drain pump.

Symptoms:

The dishwasher starts a cycle normally, but after a short period, it begins to drain unexpectedly. It might display error code 999 on the control panel. The cycle might not complete, and dishes remain dirty.

Possible Causes:

Faulty drain pump or drain motor continuously running.
Clogged drain hose or air gap, causing a false drain trigger.
Defective water level sensor or pressure switch.
Malfunctioning Main Control Board (MCU) sending incorrect drain signals.
Wiring harness damage leading to short circuits in the drain pump circuit.
Stuck or misaligned float switch.

Solution:

1

Turn OFF the dishwasher and disconnect it from the power supply at the breaker panel.
2

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

Remove the dishwasher's lower access panel. Locate the drain pump and test it for continuity using a multimeter. A normal reading is typically between 10-30 ohms.
4

Check the float switch assembly for free movement. Clean any debris that may be obstructing its movement.
5

Examine the water level sensor/pressure switch for damage or debris. Use a multimeter to check its functionality. Refer to the service manual for correct values.
6

Inspect the wiring harness and connections related to the drain pump and water level sensor for any signs of damage or corrosion. Repair or replace as needed.
7

If all other components test good, suspect a faulty Main Control Board (MCU). Replacement may be necessary. Note that some boards need to be programmed.

Safety Warning:

Always disconnect power to the dishwasher at the breaker panel before performing any repairs. Use Lock-Out/Tag-Out (LOTO) procedures. Exercise caution when working with electrical components, as high voltage is present.

Prevention:

Regularly clean the dishwasher's filter and inspect the drain hose for any signs of blockage. Ensure the air gap is free of debris. Run a dishwasher cleaner cycle monthly.

Expert Tip:

Access the dishwasher's service mode by pressing and holding the 'Start' and 'Select Cycle' buttons simultaneously for 5 seconds. This allows you to run diagnostic tests on individual components.

Frequently Asked Questions

•How do I test the water level sensor with a multimeter?

Disconnect the power to the dishwasher. Locate the water level sensor, typically at the bottom of the tub. Disconnect the wires. Set your multimeter to measure resistance (Ohms). Connect the multimeter probes to the sensor terminals. Blow gently into the sensor. The resistance should change as you blow. Refer to the service manual for specific resistance values for your model.

•Where is the drain pump located and how do I access it?

The drain pump is generally located at the bottom of the dishwasher, behind the lower access panel. Disconnect the power. Remove the access panel using a 1/4-inch nut driver. You will likely need to disconnect the drain hose and any electrical connectors attached to the pump before removing it.

•How do I know if the main control board needs replacing or if it's another issue?

The main control board should be the last component you suspect after thoroughly testing all other components, including the drain pump, water level sensor, float switch, and wiring. If all these components test within their specified ranges and the wiring is intact, the MCU is likely the culprit. However, due to the cost and complexity of replacing the MCU, it's recommended to consult with a qualified appliance technician for confirmation.

GE Dishwasher Error Code 999: Troubleshooting Draining Issues

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•How do I test the water level sensor with a multimeter?

•Where is the drain pump located and how do I access it?

•How do I know if the main control board needs replacing or if it's another issue?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: