Lg dishwasher turns off and wont respond

General
1

Brand: lg
Model Number: ldfn4542s
Main Symptom: shuts down and wont response
What happens & when: I connect the dishwasher and all the buttons on the front panel turn on and then shuts down and wont response to anything , LG technician came and said it was the main board but they change it and it does the same

Error Code (if any):
Parts or tests already tried:
Photos / video link: Microsoft OneDrive

2

Based on your description for the LG LDFN4542S, the fact that:

  • When power is applied, all the LEDs/buttons light up briefly.
  • The dishwasher immediately shuts down.
  • It does not respond to any buttons afterward.
  • The main control board has already been replaced by an LG technician, with no change.

This makes it unlikely that the main board is the cause. The problem is probably elsewhere in the control circuit.

Most likely causes (in order)

  1. User Interface (UI) / Display Board (Top Control Panel) :star: Most likely
    • A failed touch panel or UI board can prevent communication with the main control.
    • The main board powers up, attempts to communicate with the UI, then shuts down if communication fails.
  2. Wiring Harness Between the Main Board and UI
    • Broken or pinched wires in the door hinge area are common.
    • The repeated opening and closing of the door can break the communication wires inside the harness.
    • Inspect both connectors for corrosion or loose pins.
  3. Power Supply Issue
    • Verify the dishwasher is receiving a steady 120 VAC.
    • Loose wire nuts in the junction box can cause the control to reboot.
  4. Shorted Component
    • A shorted load (such as the drain pump, circulation pump, or heater) can pull down the control voltage during startup.
    • A technician can disconnect loads one at a time to identify a short.

Since the main board has already been replaced

I would focus on:

  • :check_mark: Door control panel (UI assembly)
  • :check_mark: Door wiring harness
  • :check_mark: Connectors between the UI and main board

These are much more likely than another bad main board.

A few questions that would help narrow it down

  1. Do all the lights come on for about 1–3 seconds and then go completely dark?
  2. After it shuts off, does opening and closing the door change anything?
  3. If you flip the breaker OFF for 5 minutes and back ON, does it repeat the exact same behavior every time?
  4. Did the LG technician replace only the main control board under the dishwasher, or did they also replace the touch control panel on the top of the door?

The answers to those questions can usually determine whether this is a UI board, a door harness, or another electrical issue.

3

few questions that would help narrow it down

Do all the lights come on for about 1–3 seconds and then go completely dark? Yes and they won’t turn on again until you unplugged and reconnect

After it shuts off, does opening and closing the door change anything? Nope it doesn’t change a thing

If you flip the breaker OFF for 5 minutes and back ON, does it repeat the exact same behavior every time? Yes every time

Did the LG technician replace only the main control board under the dishwasher, or did they also replace the touch control panel on the top of the door? A: only the main control was replaced and they disconnected every component one at a time to identify any short and it continues to do the same behavior

The answers to those questions can usually determine whether this is a UI board, a door harness, or another electrical issue.

4

This leads me to strongly believe that the new control board is faulty