LG Washer Main PCB Testing and Replacement Repair Guide

Unexpected error codes? A washer that won’t start or behaves erratically? When your LG front-load washer starts acting up, the main PCB (printed circuit board) might be to blame. This component controls everything from wash cycles to draining, and when it fails, your machine won’t function properly. Whether you have a gas or electric model, we’ll show you how to test and replace the main PCB to bring your washer back to life.

If you need any replacement parts for your LG washer, you can enter your model number at AppliancePartsPros.com to order them. Most orders arrive in just two business days, and we have thousands of free guides to show you how to install your new parts.

The information in this article may not apply to your specific appliance model. We recommend consulting your manufacturer’s documentation or contact us with any questions.

What you need

• Phillips screwdriver
• Side cutters
• Flatblade screwdriver
• Multimeter
• Zip tie

Safety precautions

Your safety should always be the top priority when performing any appliance repair.

• Always power off and unplug your appliance or switch off the circuit breaker before you attempt any maintenance or replacement work. This keeps you safe by eliminating any risk of electric shock. 
• If the appliance has recently been used, give it plenty of time to cool down before working on it. 
• Take your time while working to prevent accidents and personal injuries. Rushing is the enemy of precision.
• Work in a well-lit area so you can see and access appliance parts.
• Keep your workspace free of clutter and other obstacles. Keep children and pets away from the work area.
• Never work on internal parts with wet hands. Make sure the work area is completely dry.
• Check the user manual to see if there are specific installation or safety instructions related to your appliance or replacement part. 
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause personal injury.
• Wear insulated work gloves to protect your hands from sharp metal parts and debris.
• When working with wires, avoid touching any exposed wires or terminals. If you need to touch a wire, use a non-conductive tool or wear insulating gloves to prevent electrical shock.
• Always take photos or make a note of wiring terminals or other connections before disconnecting them to make reassembly easier.
• Don’t test live voltage with a multimeter if you’re unfamiliar with how to prevent short-circuiting.
• Consider wearing safety glasses and/or a dust mask when working with chemicals, dust or a large amount of debris to prevent irritation or injury.
• Turn off the water supply at the outlet before beginning repairs. Keep towels ready to catch any residual water in the system when removing parts.

How to test and replace the LG front-load washer’s main PCB

Here are the steps to test the main PCB for voltage issues and replace it if necessary. Follow each step carefully to complete the process safely and correctly.

Step 1. Access the main PCB

1. Unplug the washer from the power source.
2. Locate the rear access panel on the back of the washer.
3. Use a Phillips screwdriver to remove the four screws securing the panel.
4. Push the panel upward and lift it off to expose the internal components.

Step 2. Test the main PCB

1. Locate the motor harness at the rear of the washer.
2. Trace the harness to the left side of the rotor.
3. Identify the RPS four-wire plug containing White, Blue, Grey, and Red wires.
4. Set the multimeter to Volts DC (V with two lines on top).
5. Insert the multimeter probes into the White and Grey terminals.
6. Plug the washer back into the power outlet.
7. Close the washer door.
8. Press the POWER button on the control panel without pressing the START button.
9. Check the multimeter reading.
10. If the reading is between 10 to 15 VDC, the Main PCB and wiring are functional.
11. If the reading is 0 VDC, test the motor harness for continuity.
12. If the harness is intact, replace the main PCB.

Step 3. Remove the main PCB

1. Unplug the washer from the power source.
2. Remove the top panel by locating and removing the two lower screws from the rear plastic brackets using a Phillips screwdriver.
3. Slide the top panel back less than an inch and lift it off.
4. Undo the wire tie or push-in retainer from the top bracket.
5. Detach the black air hose from the water level switch and the clip.
6. Use side cutters to cut the zip tie securing the harness.
7. Remove the Phillips screw in the upper right corner of the PCB housing (viewed from the back).
8. Slide the control left, push up, and pull it out.
9. Free the harness along the side of the PCB housing.
10. Use a flat-blade screwdriver to release the top and side tabs of the PCB cover.
11. Remove the PCB cover and place it aside.
12. Take photos of the current PCB connections for reference.
13. Disconnect all wire plugs from the old PCB.
14. Pull out the old PCB from its mount.

Step 4. Install the new main PCB

1. Connect all plugs to the new PCB, referring to the photos taken earlier.
2. Check that all connectors are intact and fully inserted into the PCB.
3. Place the harness in the cutouts and lock the cover onto the PCB.
4. Run the side harness into the clip.
5. Mount the PCB through the rear panel and slide it to the side to lock it in place.
6. Secure the PCB with a single Phillips screw from the back.
7. Zip-tie the harness to the cover and use side cutters to trim off the excess.
8. Run the black air hose through the clip and reinstall it onto the water level switch.
9. Wire-tie the harness to the bar for proper organization.

Step 5. Reassemble

1. Reinstall the top panel by sliding it forward to lock it into place.
2. Secure the top panel with two Phillips screws at the back.
3. Plug the washer back into the power outlet.
4. Press the POWER button and check for normal operation.

We’re here to help

Thanks for following along! We hope this guide made testing and replacing the main PCB in your LG front-load washer a breeze. If you still need parts, bring your model number on over to AppliancePartsPros.com, where you’ll find millions of parts in stock and fast shipping—most arrive in only two days! If you have questions, you can reach us at 1 (877) 477-7278 or chat with us online. Make sure to swing by our DIY blog and YouTube channel for more repair tips. And don’t miss out—follow us on Facebook, X and Instagram to see our latest and greatest!