Maytag Dishwasher Error Code 9-1: Communication Error... | appliancefaults.com

Technical Background:

error code 9-1 signifies a communication problem between the main control board (MCU) and the user interface (UI) board. The MCU sends and receives signals from the UI board to manage the dishwasher's functions. These signals are typically low voltage DC. The boards communicate using a serial data protocol. If the voltage supply to either board is disrupted, or if the communication path is broken, this error will occur.

Symptoms:

The dishwasher displays error code 9-1 on the control panel. The dishwasher may not start, or it may start and then stop with the error code appearing. Some lights on the control panel might be flashing or unresponsive. The dishwasher may have intermittent issues and sometimes run a full cycle, while at other times the error reappears.

Possible Causes:

Loose wiring harness connecting control boards
Corroded or damaged wire connectors
Faulty main control board
Defective user interface (UI) board
Power supply issues affecting board communication

Solution:

1

Disconnect power to the dishwasher at the breaker panel.
2

Locate the main control board and the UI board, typically behind the control panel and at the bottom of the unit.
3

Inspect the wiring harness and connectors between the boards for any signs of damage, corrosion, or looseness. Re-seat any loose connections.
4

Use a multimeter to check the voltage at the main control board. You should have 120V AC coming into the board. Verify the board is outputting the correct DC voltages (typically 5V or 12V) to power the UI board.
5

If the voltage supply to the UI board is incorrect, replace the main control board.
6

If the voltage supply is correct, use a multimeter to check the continuity of the communication wires between the boards. Repair or replace any damaged wires.
7

If the wiring is good and the voltage is correct, replace the UI board. Reconnect power at the breaker panel after repairs.

Safety Warning:

Always disconnect power to the dishwasher at the breaker panel before performing any repairs. Lockout/Tagout (LOTO) procedures must be followed. High voltage is present in the dishwasher's electrical components. Work with caution.

Prevention:

Regularly inspect the dishwasher's wiring and connections for any signs of damage or corrosion. Ensure proper grounding of the dishwasher. Use a surge protector to protect the control boards from power surges. Avoid overloading the dishwasher, as excessive strain can lead to electrical issues.

Expert Tip:

Some Maytag dishwashers have a diagnostic mode that can provide more specific information about the error. To enter diagnostic mode, press the following sequence on the control panel within 7 seconds: High Temp > Normal > High Temp > Normal. The display will show diagnostic codes or a test cycle can be initiated.

Frequently Asked Questions

•Where exactly are the main control board and UI board located in my specific Maytag dishwasher model?

The main control board is typically located at the bottom of the dishwasher behind a kick panel. The UI board is generally located inside the control panel on the door. Refer to your dishwasher's service manual for the exact location and disassembly instructions, as it can vary by model.

•What is the correct voltage I should expect to see on the communication wires between the main control board and the UI board?

The voltage on the communication wires is typically a low voltage DC signal, often around 3.3V DC or 5V DC. Check the wiring diagram or service manual for your specific model to confirm the exact voltage range.

•How can I test the functionality of the UI board once I have verified the correct voltage is present?

Unfortunately, there is no definitive way to test the UI board's functionality with standard tools. You can visually inspect the board for burnt components. If all wiring and voltage checks out, and the error persists, replacing the UI board is usually the next step. Verify all connections are clean and properly seated.

Maytag Dishwasher Error Code 9-1: Communication Error Troubleshooting

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•Where exactly are the main control board and UI board located in my specific Maytag dishwasher model?

•What is the correct voltage I should expect to see on the communication wires between the main control board and the UI board?

•How can I test the functionality of the UI board once I have verified the correct voltage is present?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: