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Decoding the Ignition Switch Wiring Color Code

  • Car Care Tips
  • Sara Sam
  • 5 minutes

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Turn on the ignition and drive. That is certainly simple. But what goes behind may not be. Behind your car’s dashboard is a complex web of wires, each with its own story to tell. Why are some wires red while others are green or black? Here, we look at the ignition switch wiring color code and decode the rainbow of wires! 


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What Is an Ignition Switch? 

An ignition switch in a car starts the engine, period. But what goes behind it is not complex but not something we often think about. The ignition switch is responsible for sending power to the starter motor, which, as a result, gets the engine running.  

In older cars, it’s a physical part of the key barrel, and you turn the key to activate it. However, a computer handles this job in newer cars with push-button starts, closing the circuit and consequently starting the engine when you press the button. 

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How Does an Ignition Switch Work? 

The ignition coil breathes life into the car and gets it up and running. Firstly, the ignition coil takes electricity from the car’s battery and turns it into strong sparks. It is the primary winding of the coil which gathers power from the car’s battery to make a spark. Secondly, the distributor sends these sparks to special plugs called spark plugs through wires with the help of a rotor.  

Consequently, the spark plugs act when you need your car to start. In other words, the spark plugs create a spark in the engine’s cylinder, where fuel vapor awaits. They meet to result in combustion, which starts the car. 

Ignition Switch Wiring Color Code: What Does it Mean? 

The ignition switch wiring color code is like a secret language for the wires that connect the ignition switch to your car’s electrical system. In other words, it gives a better understanding of which wire does what. There can be variations in the colors based on the make of your vehicle. However, there are some common ones, which include black, red, white, and green.  

When dealing with ignition switch wiring, using the right colors is similar to following a map to avoid wrong turns. The most common wire colors you’ll come across are black, red, green, and brown. Here’s the color code cheat sheet: 

  • Black: This one’s for ground wires, like the car’s electrical foundation. 
  • Red: The power wires. 
  • Green: Green usually handles ignition duties 
  • Brown: For switched connections. 

Therefore, running your ignition system is like putting pieces of a puzzle together. Firstly, the black wire acts as a stable ground, providing a solid foundation. Secondly, the red wire delivers power. Thirdly, there is green, which connects things. While white usually handles accessories, like extra features in your car, brown can team up with white if you need a switch for something. So, it’s all about connecting these wires, and you are in for a smooth ride after you get the electrical flow just right. 

Common Ignition Switch Wire Colors 

Ignition Switch Wire Color  What does it mean? 
Red  Battery in 
Black  Ignition out 
Yellow  Starter 
Black/Yellow  Accessories 
Red/black (thick)  Radio Supply 
Red/black (thin)   Power into the key-in switch 
Grey  Off 

How To Identify Ignition Switch Wires 

The ignition switch harness in your steering wheel column will lead you to the ignition wire. Here are the types of wires that go to the terminal switches.  

Terminal  Purpose  Common Wire Colors 
BATT (battery)  Always energized  Thick red wire 
IGN (ignition input)  Controls ignition and electronics  Yellow or red wire 
ST (starter)  Connects to the starter solenoid The brown or yellow wire 
ACC (accessory) Powers car accessories  Purple wire 

Common Ignition Switch Wiring Problems 

 Ignition Switch Wiring Color Code

  • The car is not starting. 
  • Car stalls or shakes while driving. 
  • Flickering dashboard light. 
  • The key is stuck in one position. 
  • Ignition is switched on even after the key is removed. 

How to Troubleshoot Ignition Switch Wiring Problems?

  • Park your car in a safe and level spot. 
  • Identify the ignition switch terminals (BATT, IGN, ST, ACC). 
  • Disconnect the car battery’s negative terminal. 
  • Remove plastic trim pieces from the steering wheel. 
  • Optionally, remove the steering wheel using a puller. 
  • Take off the ignition module cover. 
  • Insert the key and turn it to the ACC position. 
  • Release the ignition switch and remove and examine the ignition switch. 
  • Identify and connect the positive (+) power lead to the BATT terminal. 
  • Attach the accessory wire to the ACC terminal. 
  • Connect the starter relay wire to the ST terminal. 
  • Attach the ignition wire to the IGN terminal. 
  • Reinstall the ignition switch into the cylinder. 
  • Test the ignition switch by attempting to start the car. 
  • Reassemble any removed parts and reconnect the battery. 

How Much Does It Cost to Replace an Ignition Switch? 

Based on the make and model of your car, it costs around $150 – $1500 to replace an ignition switch.  


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