How To Wire An Ignition Switch? What Wires Go To ... - Vehicle Freak

• Luka Kusic

Updated on August 23, 2022

The ignition switch has a relatively simple mechanism, but it does the vital job of directing the power from the battery to the vehicle’s accessories and to the starter.

The ignition switch has four terminals that need to be wired: the accessory, start, battery, and ignition input. Their position varies between vehicles, but the terminal in the center is most commonly dedicated to the start function.

Most of us are well aware of what the ignition switch does, but when it comes to wiring it up, it’s an entirely different story. To help you get the ignition switch installed correctly, we’ve made a detailed guide to show you how it’s done!

What Wires Go to an Ignition Switch?

Before we get into the details of how to wire an ignition switch, let’s gloss over the wires going to it and what is their purpose.

For vehicles, the standard is the 4-wire ignition switch with three terminals spread in a circle and the fourth terminal positioned in the middle. Some switches may have more than 4 connection points but the extras are generally not used.

The four wires going to the ignition switch are:

1. The battery wire.
2. The accessories wire.
3. The starter wire.
4. The ignition system wire.

The battery wire is needed to provide the current to the ignition switch which will be relayed to other components as a signal to engage their function.

The accessories wire gives the ignition switch control over the accessories such as headlights, radio, dashboard lights, etc. Disabling these functions when the key isn’t present is a precaution that prevents rapid drain of the battery.

The starter wire activates allows the power to flow to the starter and excite the magnetic field, preparing it for the task of cranking the engine.

Lastly, there’s the ignition wire, which connects to the ignition coil and puts the system in motion, cranking the engine, and activating the fuel supply and the rest of the components.

How to Properly Wire an Ignition Switch

Understanding where each of the ignition switch wires is coming from is half the job, with the other being proper wiring.

Before you start connecting the wires, keep in mind that one of them leads to the battery, so disconnect the battery terminals to avoid any safety problems or accidental engine start.

The steps to wire the ignition switch are as follows:

1. Disconnect the battery cables and make sure the vehicle is in parked gear.
2. Insert the key into the switch and make sure it’s in the off position, the furthest the key will go counterclockwise.
3. Remove the key and bring the ignition switch close to the wires in the steering column.
4. Connect the yellow battery wire to the “BAT” terminal, usually positioned at the bottom.
5. Connect the red accessory wire to the “ACC” terminal, positioned on the upper side of the ignition.
6. Connect the blue ignition wire to the “IGN” terminal, positioned on the opposite side of the accessory terminal.
7. Connect the green starter wire to the “ST” terminal, positioned in the center of the switch.
8. Reconnect the battery cables and check if anything odd happens, such as the headlights turning on or the noise coming from the starter.
9. Test the ignition switch by moving through the positions and starting the engine.

FAQs

What color do wires go to the ignition switch?

The ignition switch wires are colored red, green, blue, and yellow, each serving a specific use.

Which wire is the ignition wire?

The ignition wire should be colored blue and connects to the center of the ignition switch.

What wire goes from ignition to starter?

The starter wire should be colored green, leading from the “ST” terminal on the ignition switch to the engine starter.

What are the wire color codes?

• Phase 1 – Black colored wire
• Phase 2 – Red-colored wire
• Phase 3 – Blue colored wire
• Neutral – White-colored wire
• Ground – Bare, green, or green-yellow wire

Is the ignition wire the same as the accessory wire?

The ignition and accessory wires are not the same and you should make sure not to confuse them or the results could be dangerous for both the vehicle and your safety.

The ignition wire should be colored blue, while the accessory wire is colored red, but the colors may be different depending on the manufacturer.

Where does the ignition switch get power?

The ignition switch is powered by the battery through the cable that attaches to the bottom side of the back of the ignition switch.

Why is there no power to my ignition switch?

The ignition switch requires battery power, just like the rest of the vehicle when the engine is off. Check the battery charge first – if it’s working correctly, then inspect the ignition lock, and lastly the ignition switch to see whether it’s working properly.

Summary

As you can see, the four wires leading to the ignition switch are connected to the battery, starter, accessories, and ignition coil.

Wiring is fairly simple and requires you to match the wire’s color to the correct ignition switch terminal. The mechanic’s manual for your vehicle will have the correct wire color codes and will ensure you’ve got the right setup.

You may find other related articles here:

How To Test Ignition Switch With a Multimeter

How To Start A Car With A Bad Ignition Switch

Can The Ignition Key Be Removed When The Engine Is Running?