How to install a kill switch in the Honda Beat

Header image for How to install a kill switch in the Honda Beat


This guide will walk you through the process of installing a kill switch that disables your fuel pump. There are quite a few ways to set up a kill switches, but I like the fuel pump cut-off because, as long as the would-be criminal doesn’t find the switch, there’s no way to steal the car short of towing it. Cutting fuel (instead of the battery) means the car will also power on and crank, so it’s not immediately obvious that a security measure is at play. The thief may assume your 90s Honda is just a piece of junk and move on.

  1. 25A switch
  2. Multimeter
  3. 10mm socket/wrench
  4. 16 AWG wire
  5. Butt connectors
  6. Crimping tool
  7. Heat shrink tubing
  8. Heat gun (or hair dryer)
  9. JIS 2 screwdriver


Step 0: Access your main relay

To rig our kill switch, we’ll need access to the Beat’s main relay. Luckily, I’ve already written a guide for accessing the relay. Once you’ve worked through that tutorial, I’ll see you back here at Step 1.

Picture of ECU and main relay with the main relay circled in red.

Step 1: Unplug the main relay (technically optional)

We’re removing the main relay so we can we can determine which wire to cut to install our kill switch. I had to do this because there weren’t any resources available on the internet. In theory, all Beats should be wired in the same way and you can skip testing and jump straight to Step 3. However, there’s always a chance my Beat isn’t exactly the same as your Beat. Please test so you don’t break your car.

After gaining access to your main relay, we need to unplug it so we can access the pins on the harness.

The main relay is secured by a single 10mm fastener:

Picture showing the 10mm bolt location.

Once the fastener is removed, push in this clip and carefully wiggle the plug while pulling straight back:

Picture showing the clip on the main relay harness.

If you’re having trouble removing the plug, you can try to gently separate the parts with plastic pry tools.

Step 2: Find the fuel pump wire

With the main relay unplugged, we now need to find the wire that runs to the fuel pump.

What is a main relay?

The main relay is a single unit that contains two separate relays. When the ignition key is turned, one relay supplies power to the fuel injectors, ECU, and second relay. The second relay supplies power to the fuel pump.

Step 3:


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