How to Replace the Main Relay in a Honda Accordby Contributor
Automobile designers regulate high current devices or systems, such as the starter or fuel system, with a smaller amount of current controlled through a series of relays or switches. In Honda Accords manufactured between 1986 and 1997, the main relay serves as the "middle man" helping other devices to control the ignition and fuel system. If your Accord won't start, then you may have a damaged or broken main relay.
Verify that the problem doesn't stem from the fuel pump, ignition or any other source.
Disconnect the battery and find the main relay. Typically, the main relay on a Honda Accord rests behind the dashboard to the right or left of the steering while with accessibility up under the dashboard or behind the steering column access or dash panel. The main relay should be marked with the words "RELAY ASS'Y MAIN." If you have difficulty locating it, then confirm the exact location using the manufacturer's manual for your specific model year.
Pull the main relay from its location. You may need to push aside wires or devices or remove devices, such as the cruise control box, that block the main relay. Use your ratchet or wrench to remove any nuts and bolts (ratchet counterclockwise) attached to a device to expose the main relay or any that hold the main relay in place.
Unplug the Honda Accord's relay from the main relay socket, which is the base connected to the wiring. Keep in mind that the socket attaches to the relay via a tab that locks the relay to the socket. Without touching any of the wires, push in the tab to release the relay or use a pocketknife to pop the relay from the socket base.
Pop the new relay firmly into place by gently gripping the relay socket base and pushing the relay into it without touching the socket wiring or the solder components of the relay. Damage to the wiring's connection to the socket or to the solder can occur if either come in contact with your hands. Also, keep in mind that your new relay must fit snugly within the socket as a loose relay can overheat or cause melting of the outer casing when current runs through it.
Reverse the steps you took to remove the relay. Remember to not only securely tighten all nuts and bolts, but to also tape together with your electrical tape any loose or hanging wires.
Reconnect the battery. Start your car to confirm that your new relay works.
- Purchase a "workshop" manual through your dealer or online if your manufacturer's manual didn't include a full wiring schematic, diagram or picture showing the location of the wiring, the flow of current and switch direction placement within the Honda Accord.
- Check your old relay's solder for microscopic cracks with a magnifying glass. Often a relay stops working because a soldered joint has cracked causing resistance in the relay and a voltage drop. Symptoms of cracked solder include motor overheating or a relay that feels hot when touched. By resoldering cracked or worn areas, you can restore a non-working relay and avoid purchasing new parts.
- Never work on the electrical system without disconnecting the battery first. Live wires or electrical surges can cause burns, melt plastic or damage wiring and parts.
Items you will need
- Manual or wiring diagram
- Ratchet kit or wrench
- Pocket knife
- Main relay replacement or kit
- Electrical tape
- Magnifying glass (optional)
- Soldering tools (optional)