What Wires Go to Ignition Switch?

What Wires Go to Ignition Switch

The ignition switch is a critical component of your vehicle. It handles your car's turning by drawing power from the battery and supplying necessary areas, like the electrical components, engines, etc.

This means that if the ignition switch is faulty or the wiring is wrong, your engine won't start. To get a handle on things in your car, you'll need to first determine what wires go to the ignition switch and how they function.

A few wires go to your ignition switch, and this depends on the model of your car. In most cases, your ignition switch will have accessory wires, starter wires, battery wires, ignition input wires, etc.

Read on to understand how the ignition switch works and the function of all the wires going into it.

What Wires Go to Ignition Switch?

You don't necessarily need to be a mechanic or a professional before you understand how your car works. There are fundamental car systems that you should acquaint yourself with, like the ignition wire color code, basic ignition switch wiring diagram, and lots more.

This will help you perfectly troubleshoot, replace or rewire bad systems when the need arises, even without the aid of a professional.

Different types of wires go to your car's ignition switch. The type of wires going into your ignition switch depends on the design and model of your car.

Your car will either be running on a 4-pole ignition switch wiring or a 5-pole ignition switch wiring. The ignition positions/poles on the switch will determine how many terminals the wires will need to go to.

For instance: a 4-pole ignition switch wiring has wires that go to the following terminals.

  • Accessory
  • Battery
  • Ignition input
  • Starter

These terminals will handle the on, off, run, and start positions.

There isn't much difference with the 5-pole ignition switch wiring except that there's an extra accessory wire. In some cases, you'd find an extra battery, accessory, or starter wires.

The variation of the wires going to your ignition switch depends on the type of vehicle you are driving and its brand and model.

Initially, a car's ignition system was restricted to the use of car keys. All you needed to start a car was to slot in and twist the key. Times have changed.

Keyless and remote starters require only a push of the starter button. This further complicated the structure of the ignition switch. This implies that in some cases, you can find extra wires on your car's ignition system.

These wires can range from anti-theft systems, track-support systems, remote start systems, and lots more. You can decide to disconnect or turn off these extra connections to save battery.

To avoid confusion and unnecessary errors, it is advisable that you refer to your vehicle's service manual or wiring diagram to understand the specific wires going to the ignition switch. You must do this before working on any component in your car, especially if you're not a professional.

Types of Wires That Goes to Ignition Switch and Their Functions

Here are the four basic ignition switch wires that you should familiarize yourself with.

1. The Battery Wire (BATT)

One of the wires that go to the ignition switch is the battery wire. The battery wire creates a connection between the battery and the switch, supplying current from the battery terminal to the switch. The current supply is further distributed to other components as signals to aid their performance and functionality.

Usually depicted with a thick red color, the battery wire goes to the ignition switch from the negative and positive terminals of the battery. The primary function of the battery wire is to get power from the battery for the ignition switch.

2. The Accessories Wire (ACC)

The accessory wire goes into the ignition switch to provide power to 'accessory' devices like the radio, lights, and wipers when the engine is ignited.

The functionality of the accessory wire extends to powering your power steering, power windows, and all electrical components of your car, depending on its design.

3. The Starter Wire (STT)

The starter wire provides power to the starter through the solenoid. This runs through the relay. When there is sufficient power supply through the starter wire, the magnetic field is excited, making it possible to crank the engine.

4. The Ignition System Wire (IGN)

The function of the ignition system wire is to provide power to the ignition coil, spark plugs, and fuel injectors. This activates and controls the entire ignition system.

The role of the ignition wire extends to activating the fuel supply and ensuring the transfer of electric signal to the starter solenoid for other electrical components to function properly.

Easy Guide to Understanding Ignition Wire Color Code

You must understand that the color and location of these wires may vary depending on the make and model of your vehicle. However, there's a defined standard that is followed by most car brands.

Here's the color code of the wires going into the ignition switch:

  • Battery wire: thick red
  • Accessory wire: purple
  • Starter wire: brown or yellow
  • Ignition wire: yellow or red

These colors are not universal. Car brands can decide to modify the color to suit their needs. In some cases, the colors of these wires may fade and wear off, making it impossible for you to identify them.

Therefore, it is highly advisable that you consult your vehicle's service manual and wiring diagram or seek professional help before attempting any repairs or modifications on the wiring of your ignition switch.

Common Wiring Problems With Ignition Switches

Here are some common wiring problems with ignition switches:

  • Bad fuse, relays, and issues in the electrical circuits
  • For vehicles with an immobilizer, a broken immobilizer antenna wiring can prevent the engine immobilizer from reading transponder codes, making it impossible to start the engine.
  • Loose terminals or corrosion on battery terminals connecting the ignition switch. This can cause intermittent electrical issues or even a no-start condition.
  • Damaged or worn-out ignition switch contacts can prevent power from reaching the starter relay or solenoid. This can prevent you from starting the car or cause malfunction of the affected electrical components.
  • Incorrect wiring and connection of the ignition switch can cause short circuits, blown fuses, or cause the ignition to turn off abruptly.


The ignition switch is a delicate component of your car. Quite complex, but any error on them will greatly affect the ability of your vehicle to come on.

It's normal for you to try out things with your car, get your hands dirty with some DIY tasks, and know what wires go to the ignition switch and how to rewire them. However, we'll advise you to seek professional help, especially if you are not sure of what you're doing.

Frequently Asked Questions

What is the function of the ignition switch?

The ignition switch includes the entire system that handles the activation of your vehicle's main electrical systems and delivers power to all necessary areas of the car.  These areas include the ignition, accessories, and sometimes fuel supply.

The ignition switch is more than just the component that activates your car when you twist the metal key. It also reads the encoded programs on your keys to prevent theft.

Considering the fact that the ignition switch supplies power from the battery to the ignition system, starter motor, and engine controls, your car won't start if the ignition switch is bad.

What are the wires on an ignition?

There are different types of wires on the ignition - ranging from starter wires, ignition wires, battery wires, and accessory wires.

You'll also find spark plug wires on the ignition, responsible for transferring sparks from the ignition coil to the plugs to enable air-fuel mixture in the engine's combustion chamber.

What color is an ignition wire?

The ignition wire has different colors used to identify the different wires leading to different terminals. The typical wire colors that connect to an ignition switch and ignition wire color code depend on the specific wires in question.

For instance: the battery wire is thick red, accessory wires are purple, starter wires are brown or yellow, and the ignition wire is yellow or red. You must understand that brands can decide to change the colors of ignition wires in their vehicles to fit their brand identity.

Can I replace the ignition switch wiring myself?

Sure. Yes, you can. You can replace the ignition switch wiring yourself, although it's not advisable, especially if you don't have professional experience.

Replacing the wiring of your ignition switch will require you to unplug your battery terminals, remove the steering wheel, release pins, and do some other tasks that require extreme carefulness.

If you don't have prior experience with replacing ignition switch wiring, we will advise that you seek professional aid.

Does the ignition switch need to be grounded?

No. The ignition switch doesn't need to be grounded for it to work. Terminals in the ignition switch are usually isolated from the ground, so there's no need to ground them during connection.