LG Washer Main Control Board Testing and Replacement Guide

Is your LG washer acting up—maybe not starting, displaying error codes, or stopping mid-cycle? The main PCB (printed circuit board) is the brain of your machine, and when it fails, your washer can’t function properly. Whether you have a gas or electric model, we’ll help you determine if a faulty PCB is the culprit and whether it’s time for a replacement.

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

• Towel
• Adjustable pliers
• Flashlight
• Multimeter
• Phillips screwdriver
• Flatblade screwdriver
• Side cutters
• 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 washer’s main PCB

Below are the steps to diagnose, access, remove, and replace the main PCB in an LG washer to restore proper function.

Step 1. Test the main PCB

NOTE: Generally, for every 1 degree in temperature difference, 2 Ohms could be added or subtracted. If the temperature in your home is cooler, resistance would be subtracted.

1. Inspect all wiring and connectors for corrosion or damage.
2. Check the heater and thermistor assembly before suspecting the main PCB.
3. Turn off the water supply and unplug the washer.
4. Place a towel underneath and use pliers to remove the water inlet hoses.
5. Tilt the washer onto its left side (from the front view) and use solid support to keep it stable.
6. Locate the heater assembly at the bottom front of the outer tub.
7. Disconnect the white plug from the thermistor and remove the heater terminal contacts.
8. Set the multimeter to resistance mode (Ω symbol).
9. Touch the thermistor terminals with the multimeter probes. A good thermistor should read around 39.5K Ohms at 77°F (25°C).
10. Touch the heater terminals with the multimeter probes. A functional heater should read 12 – 18 Ohms.
11. If the reading is open circuit, the heater is faulty.
12. Set the meter to continuity mode (Wi-Fi symbol).
13. Place one probe on a heater terminal and the other on the nut in the middle.
14. If there is continuity, the heater is grounded and must be replaced.
15. If both components pass the tests, the main PCB is the likely culprit.

Step 2. Access the main PCB

1. Locate the main PCB inside the top left rear corner of the washer (from the front view).
2. Use a Phillips screwdriver to remove the two bottom screws on the rear mounting brackets.
3. Slide the top panel back slightly (less than an inch) and lift it off.
4. Undo the wire tie or push-in retainer from the top bracket.
5. Disconnect the black air hose from the water level switch and clip.
6. Cut off the zip tie securing the wires.
7. Remove the Phillips screw from the upper right corner (from the back view).
8. Slide the PCB left, push it up, and pull it out.
9. Free the harness from the side of the PCB housing.
10. Use a flat-blade screwdriver to undo the top and side tabs.
11. Remove the PCB cover and put it aside.

Step 3. Remove the main PCB

1. Take pictures of the wiring connections before unplugging anything.
2. Disconnect all plugs from the old PCB.
3. Pull out the PCB.

Step 4. Install the new main PCB

1. Connect all plugs to the new PCB, referring to the pictures taken earlier.
2. Check that all connectors are intact and properly seated.
3. Place the harness in the cutouts and lock the cover on.
4. Run the side harness into the clip.
5. Mount the PCB through the rear panel.
6. Slide the PCB to the side to lock it in place.
7. Secure the PCB with a Phillips screw from the back.
8. Zip-tie the harness to the cover and trim excess tie ends.
9. Run the air hose through the clip and attach it to the water level switch.
10. Wire-tie the harness to the bracket bar.

Step 5. Reset and reassemble

1. Slide the top panel forward to lock it in place.
2. Secure it using the two Phillips screws in the back.
3. Plug in the washer.
4. Test the machine to confirm proper operation.

Still need assistance?

Thanks for following along! We hope this guide helped you test and replace the main PCB in your LG washer. If you still need some parts, just grab your model number and head over to AppliancePartsPros.com to search for them. With over two million parts in stock, most orders ship the same day and arrive within just two days. 

Need more assistance? Our team is here at 1 (877) 477-7278 or through online chat or email. While your part is on its way, why don’t you check out our DIY blog and YouTube tutorials? And remember to stay in touch by following us on Facebook, X and Instagram!