The sweet smell of freshly cut grass, the satisfying hum of the engine, and the feeling of a well-manicured lawn – these are the joys of lawn mowing. But what happens when that familiar hum turns into a frustrating silence? A faulty lawn mower relay could be the reason behind your mower’s inability to start. This article will guide you through the process of testing your lawn mower relay and, if necessary, replacing it. We’ll break down the basics of what a relay is, how to diagnose a problem, and how to safely conduct the tests. By the end of this article, you’ll be equipped to tackle this common lawn mower issue with confidence.
What is a Lawn Mower Relay and What Does it Do?
A relay is a simple electrical device that acts as a switch, controlled by a low-voltage signal, to manage a high-voltage circuit. In a lawn mower, the relay connects the battery to the starter motor. When you turn the key to start the mower, the ignition switch sends a low-voltage signal to the relay. The relay then closes the circuit, allowing high current to flow from the battery to the starter motor, turning the engine over.
Symptoms of a Faulty Relay
A faulty relay can manifest itself in a few common ways:
- No Starting: The most obvious symptom is the lawn mower refusing to start. You may hear a clicking sound from the relay, but the engine won’t crank.
- Intermittent Starting: The mower may start sometimes, but not consistently, especially in warm weather or after the engine has been running for a while.
- Delayed Starting: The starter motor may engage with a delay after turning the key, suggesting a weakened relay.
- Clicking Sound: A constant clicking sound coming from the relay when you turn the key is a strong indication of a faulty relay.
Testing Your Lawn Mower Relay
Before embarking on the testing process, ensure the battery is fully charged. A low battery can mimic symptoms of a bad relay. Always disconnect the battery before working on electrical components to prevent electric shock.
Step 1: Locate the Relay
The relay is usually located near the battery, the starter motor, or within the electrical wiring harness. Refer to your owner’s manual or online resources to pinpoint its exact location.
Step 2: Gather the Necessary Tools
You will need the following tools for testing:
- Multimeter: This is a crucial tool for measuring voltage and resistance.
- Test Leads: These connect the multimeter to the relay’s terminals.
- Wire Crimps: These are helpful if you need to modify the test leads for a better fit.
- Small Screwdriver: This is used to remove the relay from its mounting location.
Step 3: Understand the Relay’s Terminals
Most lawn mower relays have four terminals:
- Terminal 85: This is the terminal connected to the ground (negative) side of the battery.
- Terminal 86: This is the terminal connected to the ignition switch.
- Terminal 30: This terminal is connected to the positive side of the battery.
- Terminal 87: This terminal is connected to the starter motor.
Note: The terminal numbers may vary slightly depending on the relay’s manufacturer. Consult your owner’s manual or a wiring diagram for specific terminal designations.
Step 4: Performing the Relay Test
There are two ways to test a relay using a multimeter:
Method 1: Continuity Test
- Set the Multimeter: Set your multimeter to the continuity setting, usually represented by a diode symbol or “Ω” (ohm) symbol.
- Connect the Test Leads: Connect one test lead to terminal 86 and the other test lead to terminal 87.
- Check for Continuity: If the relay is good, the multimeter should show continuity. This means a low resistance reading is displayed on the multimeter, usually below 1 ohm. A high resistance reading or no reading at all indicates a faulty relay.
Method 2: Voltage Test
- Set the Multimeter: Set your multimeter to the voltage setting (DC or AC depending on your relay’s type).
- Connect the Test Leads: Connect one test lead to terminal 30 and the other to terminal 87.
- Turn the Key: While maintaining the connection, turn the ignition key to the “Start” position.
- Check for Voltage: If the relay is working, you should see a voltage reading that matches the voltage of your battery. If there’s no voltage reading, the relay is faulty.
Note: If you have a battery-powered lawn mower with a DC relay, ensure you have a DC multimeter. AC multimeters are used for testing AC circuits.
Replacing the Lawn Mower Relay
If the tests confirm a faulty relay, replacing it is necessary. Here’s a step-by-step guide:
- Disconnect the Battery: Always disconnect the battery terminals to prevent electrical hazards.
- Locate and Remove the Relay: Locate the relay and use a small screwdriver to remove it from its mounting location.
- Identify the New Relay: Ensure you purchase a relay that matches the original’s specifications, including the number of terminals and voltage rating.
- Install the New Relay: Carefully insert the new relay into the mounting location, ensuring the terminals align properly.
- Reconnect the Battery: Reconnect the battery terminals and ensure all connections are secure.
Tips for Troubleshooting Relay Problems
- Check for Loose Connections: Ensure all electrical connections are tight and clean. Loose or corroded connections can impede current flow and mimic a bad relay.
- Inspect the Wiring: Examine the wiring harness for damage or fraying. Damaged wiring can cause short circuits or open circuits, hindering the relay’s function.
- Test the Ignition Switch: A faulty ignition switch can prevent the relay from receiving the signal to activate. Test the switch for proper continuity using your multimeter.
- Inspect the Starter Motor: A faulty starter motor can create a heavy load on the relay, potentially causing it to fail. Test the starter motor for continuity using your multimeter.
Conclusion
While a faulty lawn mower relay can be frustrating, understanding how to test and replace it empowers you to tackle the problem independently. By following the steps outlined in this article, you can diagnose and address this issue confidently, ensuring you get back to enjoying the satisfaction of a well-maintained lawn in no time.
Frequently Asked Questions
What is a lawn mower relay, and what does it do?
A lawn mower relay is a small electrical switch that controls the flow of power to the motor. It acts as a bridge between the ignition switch and the motor. When the ignition switch is turned on, the relay closes, allowing electricity to flow to the motor and start it. If the relay fails, the motor will not receive power, and the lawnmower will not start.
Relays are essential for protecting your lawnmower’s electrical system. They prevent high current from flowing directly through the ignition switch, which could damage it. A relay is a simple and robust component that can be easily tested and replaced if needed.
How can I tell if my lawn mower relay is faulty?
There are a few signs that can indicate a faulty lawn mower relay. The most common symptom is that the lawnmower will not start, even though the battery is charged and the ignition switch is turned on. Other symptoms include the motor clicking but not turning, or the motor running erratically.
If you suspect your relay is faulty, you should test it. There are several methods to test a lawn mower relay, and most of them involve using a multimeter. A faulty relay will often show an open circuit, meaning there is no continuity between the terminals.
How do I test my lawn mower relay?
Testing your lawn mower relay is a straightforward process. You will need a multimeter to perform the test. Disconnect the relay from the wiring harness. Set your multimeter to the continuity setting. Touch the probe to the terminal where the power wire is connected and the other probe to the terminal where the motor wire is connected.
If the multimeter beeps, the relay is working. If it doesn’t beep, the relay is faulty and needs replacement. Testing the relay with a multimeter is a quick and easy way to diagnose a faulty relay.
What should I do if I find a faulty relay?
If you find a faulty relay, you will need to replace it. First, you need to locate the relay. It is usually mounted near the engine or the battery, and it is usually a small black box with several wires connected to it. Disconnect the wires from the relay.
Once you have located the relay, you will need to purchase a new one. Ensure you get a relay compatible with your lawnmower model. After purchasing a new relay, you can install it by connecting the wires to the new relay in the same way they were connected to the old relay.
How do I replace my lawn mower relay?
Replacing a lawn mower relay is a simple process. The first step is to locate the relay on your lawnmower, which is usually near the engine or battery. Once you have located it, disconnect the wires connected to the relay.
After removing the old relay, carefully install the new one. Connect the wires to the new relay in the same order they were connected to the old relay. It is important to ensure that all connections are secure and that the relay is mounted properly.
What precautions should I take when working on my lawn mower’s electrical system?
When working on your lawnmower’s electrical system, it is crucial to take necessary precautions to prevent injury. Disconnect the battery from the lawn mower before starting any work. This will prevent any accidental shocks or electrocution.
Additionally, be careful not to touch any exposed wires or terminals, as these can carry a dangerous electric current. It is also important to use insulated tools when working on electrical components to avoid accidental shocks.
How can I prevent my lawn mower relay from failing?
While there is no foolproof way to prevent your lawn mower relay from failing, there are a few things you can do to extend its lifespan. Regularly check the battery connections and ensure they are clean and tight.
Avoid using the lawn mower in extreme weather conditions, as heat or cold can stress the relay. Also, avoid using the lawn mower when the battery is low. This can cause the relay to overheat and fail prematurely. Following these tips can help prevent your lawn mower relay from failing.