Rywire Main Relay Kill Switch Harness

Honda Main Relay Kill Switch & Upgrade Harness - OBD0 / OBD1-OBD2 (Civic, Accord, Integra)

Got an older Honda or Acura that won't start because the main relay died again? This Rywire main relay upgrade harness fixes that permanently. It replaces the failure-prone factory Honda main relay with a standard automotive relay you can grab at any parts store for a few bucks, and it adds a removable kill switch that cuts power at the relay level, so the car won't start unless the switch is plugged in. No cutting or splicing your factory harness, just plug it in and you're done.

Why The Honda Main Relay Fails

If you've owned an older Civic, Accord, or Integra, you already know the main relay problem. The factory relay sits in the dash where it gets hot, and the solder joints inside crack over time. When it fails, the fuel pump won't prime and the car won't start, leaving you stranded, and a new factory relay costs far more than it should. This harness swaps the Honda-specific relay for a standard automotive relay. When that relay eventually wears out, you're not waiting on a special-order part or paying dealer markup, you grab a new relay from any parts store and swap it in five minutes.

A Hidden Kill Switch That Actually Works

The harness includes a removable toggle switch that interrupts power to the main relay. No power to the relay means the fuel pump doesn't run and the car won't start. Someone can turn the key all they want, but without that switch plugged in, the car isn't going anywhere. You unplug the switch and take it with you when you park. It's not a hidden toggle under the dash that a determined thief can find, they'd need the actual switch in hand to start your car, which makes it a simple, effective theft deterrent on a car that predates modern immobilizers.

Plug It In, You're Done

The harness plugs straight into your factory main relay connector. Unplug the old relay, plug in the Rywire harness, mount the new relay somewhere convenient, and route the kill switch wherever you want it. No cut wires, no soldering, and the whole install is reversible if you ever want to go back to stock.

OBD0 Or OBD1/OBD2? Order The Right One

Order the version that matches your chassis:

• OBD0: pre-1992 Honda and Acura (white plug).
• OBD1 / OBD2: 1992+ Honda and Acura. The OBD1 version works on both OBD1 and OBD2 chassis (red plug).

Check your build year and order accordingly.

What You Get

• Rywire main relay upgrade harness
• Standard automotive relay
• Removable kill switch
• Plug-and-play installation, no cutting or splicing

Compatible Vehicles

• OBD0: pre-1992 Honda and Acura (white plug)
• OBD1/OBD2: 1992+ Honda and Acura (red plug)

If your old Honda keeps stranding you over a dead main relay, this is the permanent fix, cheap off-the-shelf relays from here on, plus a kill switch you take with you for peace of mind. Just keep the switch with you when you park, since without it the car won't start, and order the OBD0 or OBD1 version to match your chassis.