Kenmore Washer Error Code F28: CCU/MCU Communication... | appliancefaults.com

Technical Background:

The CCU is the main control board of the washer, responsible for managing the wash cycle. The MCU controls the motor speed and direction. error code F28 indicates a loss of communication between these two components. This communication typically occurs via a low-voltage serial data line. Voltage readings on this line should be in the 3-5V DC range when communicating.

Symptoms:

The washer may not start, may display error code F28 on the control panel, and the motor may not operate.

Possible Causes:

Loose wiring harness connection between CCU and MCU
Damaged wiring harness between CCU and MCU
Faulty CCU (Central Control Unit)
Faulty MCU (Motor Control Unit)
Power surge damaging either the CCU or MCU

Solution:

1

Disconnect power to the washer at the breaker panel.
2

Locate the CCU and MCU, typically behind the control panel and near the motor, respectively.
3

Inspect the wiring harness connecting the CCU and MCU for any visible damage (cuts, kinks, or burns).
4

Disconnect and reconnect the wiring harness at both the CCU and MCU to ensure a secure connection. Use a multimeter to check continuity of each wire in the harness.
5

Restore power to the washer and check for error code F28. If the code persists, use a multimeter to check for 5V DC at the communication pins of both the CCU and MCU. If voltage is missing, suspect a faulty CCU.
6

If the code still remains and the 5V DC is present, replace the MCU.
7

After replacing either component, run a diagnostic cycle to ensure proper operation.

Safety Warning:

Always disconnect power to the appliance at the breaker panel before performing any repairs. Lock Out/Tag Out (LOTO) procedures should be followed to prevent accidental re-energizing of the circuit. High voltage is present within the washer, posing a shock hazard.

Prevention:

Avoid overloading the washer, use a surge protector to protect the electronics from power surges, and periodically inspect the wiring harness for any signs of wear or damage.

Expert Tip:

To enter diagnostic mode on many Kenmore washers, with the washer unplugged, press and hold the Start/Pause button, plug the washer back in, and release the Start/Pause button after 5 seconds. This may allow you to clear the error code or run a test cycle.

Frequently Asked Questions

•How do I locate the CCU and MCU in my specific Kenmore washer model?

Refer to the washer's service manual or online parts diagrams. They are often located behind the control panel and near the motor, respectively. Search online using your model number.

•What voltage should I expect to see on the communication wire between the CCU and MCU?

Typically, this is a low-voltage DC signal, usually around 3-5V DC. Use a multimeter to test this.

•If the wiring harness appears fine, and I've checked the connections, which component is most likely to be the issue – the CCU or the MCU?

It's difficult to say definitively without further testing, but a faulty MCU is slightly more common, especially if the motor is not responding at all. However, a faulty CCU can also cause this error. Replacing the MCU first is often a reasonable strategy due to cost and accessibility.

Kenmore Washer Error Code F28: CCU/MCU Communication Fault Troubleshooting

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•How do I locate the CCU and MCU in my specific Kenmore washer model?

•What voltage should I expect to see on the communication wire between the CCU and MCU?

•If the wiring harness appears fine, and I've checked the connections, which component is most likely to be the issue – the CCU or the MCU?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: