A bad main relay can cause several performance issues in your Honda car. It’s one of the reasons your Honda cannot start, misfires, suddenly stalls, or shows the check engine light. If you’re driving and the main relay fails, you may bypass it before finding a replacement.
Bypassing a main relay in your Honda vehicle should be a temporary fix. It can be a quick solution to help you start the engine and keep driving. However, since the main relay is critical to your car’s engine parts, you must find a permanent solution soon after.
Herein, I detail how to bypass a Honda main relay in simple steps. You’ll also learn the consequences of bypassing this relay.
Question: What Is the Role of a Honda Main Relay?
The main relay controls electrical energy flowing to most of your Honda vehicle’s electrical components. It powers your car’s ECM, fuel injector, and ignition system. When these parts receive electrical power, you can start and run your vehicle without encountering issues.
A Honda main relay works when you turn on the ignition. Doing so allows the main relay to close the circuit and send power to the ECM. Then the ECM controls the fuel injector to ensure the engine receives the correct mixture of fuel and air.
The main relay stays closed while the engine runs to allow a consistent power flow. If the main relay fails while driving, your engine might misfire, lose power, and shut down.
A Honda main relay fails due to the following:
- Wear and tear: The main relay succumbs to wear and tear, especially due to excessive use, causing the actuator and contacts to fail.
- Excessive voltage: Exposure to excessive voltage can burn out and damage the contacts and coil.
- Overheating: An overheating engine can damage the main relay due to excessively high temperatures.
- Corrosion: Moisture, road salt, or chemicals can lounge on the main relay and cause corrosion. If not addressed on time, corrosion will cause the main relay to fail.
If your Honda has a defective main relay, you can bypass it before installing a new part. But before you bypass the main relay, ensure you have the following:
- Safety gloves and glasses
- Your car manual
- Screwdriver
- Pliers
- Wire cutter
- Jumper wire
- Electric tape
Answer: How To Bypass a Honda Main Relay
You can bypass the main relay after gathering the above tools and materials. But disconnect your Honda car’s battery before bypassing the relay to avoid electrical shocks.
Start by turning off the engine and wearing your safety gloves and glasses.
Then pull out the negative cable to disconnect the battery. You can use the pliers to remove the nut on the negative terminal.
After disconnecting the battery, use these detailed steps to bypass your Honda main relay.
Access the Honda Main Relay
The location of a main relay varies depending on the Honda’s make and model. However, you’ll usually find this component under the dash, just near the pedals.
If you’re unsure where to find the relay, check your vehicle’s manual for its exact location. Use your screwdriver to open the lower panel of the dash to access this component. The main relay is rectangular and has a few wiring connectors.
Identify the Relay Terminals
This is a crucial step as it helps you understand which terminals to connect with your jumper wires. And since the main relay has several terminals (wiring connectors), you’ll need to find the ones needed. These terminals are labeled with a letter or number for easier identification.
Find the power supply marked “B” that gets power from the battery. Then look for the fuel pump terminal labeled “E” or “5” that allows power transmission to the fuel injector.
Prepare the Jumper Wire
Use the wire cutter to strip the insulation on both ends of the jumper wire. The aim is to access about 1-1.5 inches of the wire’s ends.
Connect the Jumper Wire
Bypassing a Honda main relay involves connecting the power supply terminal (labeled “B”) and the fuel pump terminal (labeled “E” or “5”). Attach one end of the jumper wire to the power supply terminal and the other to the fuel pump terminal.
Secure the connections to ensure they’re tight. Then use the electrical tape to cover the connecting points.
Note: You can remove the main relay by pulling out the wires and unscrewing the attaching screws. After disconnecting the relay from your Honda vehicle’s body, strip off the insulation on the ends of the power supply wire (terminal “B” wire) and the fuel pump wire (terminal “E” or ” 5” wire).
Attach the two wires with a wire nut or crimp connector. You must ensure the joint is secure. This method will also help bypass your Honda main relay.
Reconnect the Battery
After connecting the jumper wire, reconnect the battery and ensure the connections are secure. You only need to reattach the negative cable and tighten the nut.
Test Your Vehicle
Turn the ignition on after reconnecting the battery. Doing this will allow the fuel pump to start working. If you’ve successfully bypassed the main relay, your engine should start and run without encountering issues.
Remember that bypassing your Honda main relay is not a permanent fix for a defective relay. You should use this method if you’re driving and the main relay fails. After bypassing the relay, drive home or to a repair shop to install a new, functional Honda main relay.
However, if your Honda car doesn’t start or run after bypassing the main relay, examine the vehicle for other issues. You can also call an expert to inspect and fix the car.
Answer: Consequences of Bypassing a Honda Main Relay
After understanding how to bypass a Honda main relay, knowing what will happen with your car is essential. The good news is, bypassing the main relay solves your immediate problems. You can start the vehicle and drive home or to the workshop.
However, bypassing the main relay has several side effects. So, what might happen when you bypass the relay?
- Higher current levels: The main relay controls the current flow to ensure components get the correct electrical energy. Bypassing it can result in higher current levels flowing through the circuit. This current might blow the fuse and damage the wires.
- Leaking current: Unstable connections and inappropriate wrapping of the jumper wire and the connecting points can cause voltage to leak.
- Reduced engine life: Bypassing a Honda main relay shortens the engine’s lifespan due to fluctuating current flows. Various electrical components in the engine might perform poorly due to overcurrent or undercurrent issues. When components fail, they will affect the engine’s performance and lifespan.
- Invalidated warranty: Bypassing the main relay can cause issues with your Honda car’s engine, fuel pump, electrical appliances, or other components. If the manufacturer finds these issues result from a bypassed main relay, they will invalidate your warranty. This can happen if your car is still under the warranty period.
Frequently Asked Questions
Below are answers to commonly asked questions about the Honda main relay.
How long does the main relay last?
The main relay can last up to 50,000 life cycles (up to 100,000 km). However, this can vary depending on the relay’s quality, usage, and environmental factors. The main relay might fail sooner than expected due to excessive heat, corrosion, and electrical surges.
Can I drive with a malfunctioned Honda main relay?
The main relay is critical to your car’s operations and the engine’s lifespan. So avoid driving your vehicle if it has a bad main relay. Driving with a faulty main relay can cause your Honda car to lose power and stall, leaving you stranded.
How much does it cost to replace a main relay?
Replacing a main relay in your Honda car might cost between $65 and $75. The new main relay costs around $35-$40, while labor costs around $30-$35. If you’re an experienced DIYer, you can replace the main relay and cut the overall cost by half.
Wrap Up
I hope that you now know how to bypass a Honda main relay if it malfunctions. Bypassing the main relay in your car should be a temporary solution to get you out of trouble while driving. Make sure to replace the bad main relay after reaching home or the nearest repair shop.