ignition interlock device

How to Use an Ignition Interlock Device

February 8, 2019

So, you have the ignition interlock device installed. You’ve gotten all the paperwork filed and you’ve received your restricted license. Although you can’t change your conviction, you can ease the experience of using an interlock and successfully complete your program if you know what to expect.


There are many different types of ignition interlock devices – some are simple, electronic devices and some can get pretty fancy with “positive ID cameras.” Before you panic though, realize that “fancy” doesn’t mean complicated. In fact, interlocks, once you know how it works, are pretty easy.


Using an ignition interlock like the easy-to-use devices from Draeger, is all about knowing the sequence of steps to provide a breath sample in order to and start your vehicle. Rest assured, at your installation appointment the technicians will go over all the steps with you to ensure you are using your ignition interlock properly.

But first, how does it work?

An ignition interlock prevents someone who has been drinking from starting their vehicle. The device, usually about the size of a cell phone. It is hard-wired to your vehicle, connecting directly to your vehicle’s ignition system. It has a preset level for blood alcohol concentration (BAC), which is pre-determined by your state. If you blow into the ignition interlock when you are over the set limit, your vehicle will not start. It will lock your vehicles starting mechanism for a period of time determined by your state – usually between 5 to 30 minutes. Once that time has passed, you can test your BAC again. Each time you fail the test, the device locks the ignition for a longer period.

Once the car starts, you’ll be required to take additional tests called “rolling re-tests.” A rolling retest is where your ignition interlock device randomly goes off asking you to provide a breath sample while the vehicle is running. Typically, you are given at least 5 minutes to pull over safely and provide the test. If you fail the rolling retest, your vehicle will sound its alarm and/or horn and lights will flash until you pull over and turn off the engine. In order to turn your vehicle back on, you’ll have to pass a breath test.

How do you use it?

When you’re ready, you’ll need to power on your ignition interlock device. Depending on the model, you will either press a button on the Interlock, turn the key to your car or press cars start button. The interlock device will power up and let you know when it’s ready for a test. Take a deep breath in then blow into the mouthpiece on the device like the Service Technician taught you. If your breath registers under the allowed BAC, you can start your engine and drive. If you do not pass the test, you must wait to try again.

Maybe you’ve heard of complications using an IID. We recommend contacting your provider with questions. There are a lot of myths out there regarding the device, so it’s better to be fully informed than to guess. All breathalyzers must be calibrated periodically in order to maintain accuracy, so IID providers are constantly checking their equipment.

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