Car Breathalyzer Houston (Ignition Interlock Device)

Police officers from coast to coast are stepping up the enforcement of drunk driving laws. People caught driving while intoxicated(DWI) are arrested and fined (Click Here for more information about DWIs). In a growing number of cases, they are required to have an ignition interlock device installed. An ignition interlock device is a mechanism that measures a person’s blood alcohol content (BAC). It is attached to the dashboard of the vehicle after a person is charged with multiple DWIs. They must blow into it before they can drive. If their BAC is above the legal level the vehicle will not start.

The ignition interlock devices are relatively simple. The device is placed in the glove compartment of the vehicle and connected to the vehicle’s ignition system by wires. Before the person can start the vehicle they must blow 1.5 liters of air into the system. If the driver’s BAC is over a certain level, usually between .02% and .04%, the vehicle will not start. Whether the driver passes or fails, content is saved on a computer chip that can be downloaded by law enforcement.

Many ignition interlock devices conduct “rolling tests.” Once the vehicle is in motion the system calls for the driver to blow into the device at random intervals of between 5 minutes to 30 minutes. These tests keep a sober person from blowing into the ignition interlock device to get the vehicle to start then allowing an impaired person to drive. The rolling tests are also designed to stop the driver from drinking alcohol once the vehicle is moving.

Should the driver blow a BAC over a safe level during the rolling test or fail to give a breath sample, the device will cause the horn to sound incessant or the lights to flash on and off until the car is turned off. The alarm system does not turn off the engine while the car is in operation for safety reasons. The ignition will not restart until the driver blows an alcohol-free breath sample into the ignition interlock device.

Ignition interlock devices require monthly maintenance. They are checked at regular intervals to ensure that they have not been tampered with. The information contained in the computer chip can then be forwarded to law enforcement or the court. It will let them know if the driver has ignored the rolling tests or has blown above acceptable limits.

What is an ignition interlock?

An ignition interlock device (IID) is a breath alcohol analysis device that is installed in a motor vehicle.  The Interlock prevents a driver from starting a vehicle if the driver’s breath alcohol concentration (BrAC) is above a pre-set fail level.  If the BrAC is under the pre-set fail level, the IID will allow the ignition of the vehicle to start the engine.

If a valid breath sample is not provided, or if the BrAC is at or above the pre-set fail level, the ignition will be disabled thus preventing the engine from being started.  The Interlock system records a variety of information including dates, times, test results, engine runs and engine offs.  This data is provided to designated authorities and used to determine compliance with the respective Interlock program.

How does it work?

The device will be activated once the key has been put into the vehicle’s ignition and turned on.  The device will prompt the driver to blow into the device to provide a breath sample.
If the breath alcohol concentration (BrAC) analyzed in the breath sample is below the pre-set fail level the engine can be started.   If the BrAC is at or above the pre-set fail level, the ignition will be disabled and the vehicle will not start.  The IID will “Lockout” for a short period of time.

Once this period has expired, another breath sample can be provided. At random times during vehicle operation, the IID will prompt the driver to provide another breath sample or a running retest.  If the breath sample for the retest is failed or missed, the IID will log the event as a violation, warn the driver, and in some cases start up an alarm (e.g. lights flashing, horn honking, etc.) until the ignition is turned off, or a valid breath sample is provided.

What is the process of having the IID installed, monitored and removed?

Installation:  Once an individual has an IID restriction, an appointment is scheduled with a service center for the installation of the IID.  At the initial installation, the participant will be trained on how to use the device and the applicable program requirements.

Monitoring:  The IID will need to be monitored regularly (usually once a month or every two months) so that the IID data can be uploaded, and the device can be calibrated.

Removal:  Once the order has been issued removing the IID restriction, the participant can then schedule a removal appointment.

How much does it cost?

Every state and IID manufacturer has different prices, but they range anywhere from $65-$100 per month.  However, additional fees may apply for installation, calibrations, maintenance, or violations.

What are the benefits?

Most importantly is keeping intoxicated drivers from operating a motor vehicle.  For DUI offenders an IID allows the participant to retain their driving privileges for the duration of their probation.   IIDs can be voluntary as well, which can result in reduced insurance costs.

Can I bypass the device?

IIDs are able to detect if an air pump or filter is being used to provide the sample.  A violation would be recorded at that time.

What if the vehicle stalls in traffic?

The IID will allow the ignition to be restarted without providing a breath test for a couple of minutes following the engine’s cease of operation.  This will allow the driver a sufficient amount of time to quickly restart the engine.

Will the unit shut off the engine?

No.  An IID does not shut off a vehicle’s engine or stop it abruptly in its tracks.  If a retest is failed or if the retest is not presented when required, a violation will be recorded and the vehicle’s horn may sound and the lights may flash until either the breath test is passed or the vehicle is turned off by the driver.

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