How to check washing machine parts with Digital multimeter

Washing Machine Troubleshooting Guide

When a washing machine displays an error code, it’s usually because a part isn’t working correctly or a signal from a sensor didn’t reach the main control board (or Motor Control Unit, MCU). These signals come from various sensors and parts, such as:

• Pressure sensor (monitors water levels)
• Temperature sensor (checks water temperature)
• Soil sensor (detects dirt levels in water)
• Hall sensor (tracks the drum’s speed and position)
• Inlet valve (controls water intake)
• Touch sensor (detects touch inputs)

Here are some tips to check these parts when troubleshooting:

Inlet Valve

The inlet valve in a washing machine is a solenoid valve that opens and closes to allow water into the drum. It operates on either AC or DC power, depending on the brand or model. Some washing machines have multiple valves for different functions, like jet spray, pre-wash, or rinse.

External Check

1. Power Test: Connect the valve to the appropriate AC or DC power supply (as specified on the valve). If it vibrates, the valve is functioning. If there’s no vibration, the valve might be faulty.
2. Multimeter Test: Set the multimeter to resistance mode and place the probes on each terminal pair.
   • A good valve should show a reading between 1K and 5K ohms.
   • If the reading is 0 ohms (short) or “1” (open), the valve is faulty.

Internal Check (Using Test Mode or Normal Operation)

1. Start a Program: Run the washing machine on a normal cycle or test mode (if available). After the machine senses the load and displays the time, check if water enters the drum.
2. Voltage Check: If water isn’t coming in, check the voltage across the valve’s terminals.
   • If there’s no voltage (check for AC or DC as labeled on the valve), inspect the wiring continuity and main PCB. If the wiring is fine, the main PCB may need to be replaced.
   • If there is voltage, but water isn’t entering, verify the water supply pressure. If pressure is adequate, the valve likely needs to be replaced.

Pressure Sensor

A pressure sensor measures the amount of water needed in a tub by converting the pressure into an electrical signal. To test a pressure sensor, you use a multimeter set to measure resistance (ohms).

Diagnosing a “No Power” Issue

1. Set the multimeter to VAC mode and check the power supply at the wall outlet.
2. If power is present at the outlet, next check the noise filter’s output voltage and then the voltage at the PCB (Printed Circuit Board) input terminal.

Keep in mind that power supply standards vary by country…

Drain Motor Check

In automatic washing machines, a “drain error” or issue will trigger an error code if a problem with draining is detected…

Child Lock in Washing Machines

The child lock feature is a safety function designed to prevent children from accidentally operating the washing machine…

Motor Error

A washing machine motor error is indicated if the wiring or motor winding is open…

Top load washing machine

How to check Inlet valve or water valve

Inlet Valve in Washing Machines: Overview and Testing Guide

Overview

The inlet valve in washing machines is designed in various configurations:

• Single, double, triple, or even multiple valves.
• These valves are connected to the drum and dispenser to control water flow.

Testing Procedures

1. Multimeter Test

• Set the multimeter to the 20K ohm range.
• Place the probes on each pair of valve terminals.
• Expected resistance values:
  • AC Valve: 4K to 5K ohms
  • DC Valve: 0.6K to 1.3K ohms

2. Voltage Check

• During operation (e.g., the initial 5 minutes of the wash cycle), measure the voltage:
  • AC Valve: 230 VAC
  • DC Valve: 12 VDC
• If voltage is present but the water supply does not work, replace the valves.

Physical and Visual Inspection

• Visual Check:
  • Inspect for visible damage, such as burnt marks or melted plastic on the valve.
• Operation Test:
  • Start the washer on a quick wash program.
  • Verify water flow within the first 5 minutes.
  • Stop the washer and ensure the water supply also stops immediately.

Conclusion

If any faults are detected during these tests, replace the inlet valve to ensure proper water flow and machine functionality. Always handle electrical components with care and ensure safety measures are followed.

Pressure sensor

Pressure Sensor Details and Testing Guide

Functionality

The pressure sensor monitors water levels and sends signals to the main PCB. Based on these signals:

• The inlet valve starts or stops water flow, depending on the signal level.

Terminal Identification

Viewed from the top:

• Terminal 1: Most right
• Terminal 2: Middle
• Terminal 3: Left side

Testing Procedures

1. Multimeter Continuity Check

• Set the multimeter to the continuity/ohm range.
• Place the probes on Terminal 1 and Terminal 3.
• Expected resistance value: 19 ohms to 26 ohms.

2. Physical Inspection

• Inspect the pipe connecting the sensor to the drum for:
  • Damages
  • Blockages
• Disconnect the pipe from the sensor and blow air through it:
  • Air should pass freely.
  • If water is present in the drum, bubbles should form.

3. Live Operational Test

• Remove the sensor pipe near the drum.
• Start the washer.
• Blow into the disconnected pipe at normal pressure:
  • The washer drum should start, and the water supply should stop.
  • Releasing the pressure should allow the washer to take in water again.
• Measure voltage during operation:
  • Terminal 1 to Terminal 3: 2.5 VDC
  • Terminal 1 to Terminal 2: 2.5 VDC

Note: Ensure all tests are performed safely, and power is disconnected when making physical inspections or adjustments.

Top Load washing machine

How to check drain motor

Drain Motor (Top Load): Overview and Testing Guide

Overview

Drain motors in top-load washing machines come in two main types:

• 2-Terminal Motors:
  • Commonly used in various brands.
  • Simple to test live or visually.
• 3-Terminal Motors:
  • Typically used in LG washers.
  • Operates in both wash and spin modes with additional functionality.

Functionality

• The motor, equipped with gears, works on either AC or DC supply.
• 2-Terminal Motors:
  • When set to spin/drain, the motor lever engages to pull the dump valve, allowing water to drain from the drum.
• 3-Terminal Motors:
  • During wash mode, the motor aligns the clutch assembly for washing.
  • During spin mode, the motor:
    • Aligns the clutch assembly for spinning.
    • Opens the dump valve to drain water from the drum.

Testing Procedures

1. Multimeter Test: 3-Terminal Drain Motor

DC Drain Motor

• Set the multimeter to resistance mode.
• Top view terminal positions:
  • Pin 1: Right
  • Pin 2: Middle
  • Pin 3: Left
• Resistance Values (Pull the lever halfway out):
  • Pin 1 to Pin 2: 90–110 ohms
  • Pin 1 to Pin 3: 40–60 ohms

AC Drain Motor

• Set the multimeter to resistance mode.
• Top view terminal positions:
  • Pin 3: Left
  • Pin 2: Middle
  • Pin 1: Right
• Resistance Values (Push the lever halfway):
  • Pin 1 to Pin 3: 10K ohms
  • Pin 2 to Pin 3: 6K ohms
• Voltage Supply Test (Live Operation):
  • Pin 1 to Pin 2: 230V AC during washing
  • Pin 1 to Pin 3: 230V AC during spinning

2. Multimeter Test: 2-Terminal Drain Motor

• DC Type:
  • Set the multimeter to resistance mode.
  • Pin 1 to Pin 2: 90–120 ohms
• AC Type:
  • Set the multimeter to resistance mode.
  • Pin 1 to Pin 2: 8K–11K ohms

Notes and Precautions

Perform live tests carefully to avoid electrical hazards. Replace the motor if the resistance or voltage values are not within the specified ranges. Always disconnect the washer from power before conducting physical inspections or adjustments.

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