Don´t drink and drive

Alcohol immobilizer

alcohol immobilizer from alcowarn


Alcohol immobilizer

The TruckWarn breath alcohol ignition interlock device (BAIID) prevents the vehicle from starting under the influence of alcohol.

PreLock 85, the alcohol immobilizer from TruckWarn

The alcohol immobilizer consists of two parts: a hand-held device with a measurement indicator and a control unit, which is installed under the dashboard cover and within reach of the driver’s seat.

The driver first activates the ignition. Then, for example, a signal tone or an LED light on the handheld device prompts the driver to provide a breath sample. The hand-held device measures the alcohol concentration in the breath and after about five seconds the result is shown on the display.

If the measured breath alcohol value is not higher than the previously programmed value (e.g. a legal limit), the control unit activates the starter current. The engine can now be started.

However, if the exhaled alcohol concentration is too high, the control unit blocks the starter motor and thus prevents the engine from starting.

How an alcohol immobilizer works

The process of using an alcohol immobilizer from TruckWarn is quite simple:

  • The driver turns the ignition key to start.
  • Mandatory administration of a breathalyzer test is indicated.
  • Through a mouthpiece (replaceable for hygienic reasons) on the hand-held device, the driver gives a breath sample.
  • After approx. 5 seconds, the result of the breath alcohol content is shown on the display of the hand-held device.
  • Only if the previously entered limit values are not exceeded, the ignition is enabled.

Nothing stands in the way of an alcohol-free and therefore safe journey in road traffic.

How We Help You Succeed…

An alcohol immobilizer, also called an Ignition Interlock Device, Alkolock or Alcohol Interlock, combines a breathalyzer with an immobilizer. By performing a breath alcohol test before starting the engine, the driver who is under the influence of alcohol is prevented from starting the vehicle engine.

An alcohol immobilizer thus protects other road users from a possible drunk driving accident. Alcohol interlock devices can be used as a preventive measure.

Alcolock’s alcohol immobilizer is a combination of a handheld meter, which is placed within reach of the driver, and a control unit, which is usually installed underneath the dashboard cover.

The driver gives his breath sample to the hand-held device via a mouthpiece. The integrated breath alcohol measuring device measures the alcohol content of the breath sample. Each breath sample given or also aborted are stored. If a test of the breath alcohol content reveals that a stored limit value has been exceeded, the ignition of the motor vehicle is blocked.

Only a positive breath test can enable the ignition of the vehicle. Both components form a reliable unit designed to prevent drunk driving.

Alcohol interlocks and alcohol immobilizers are the same systems. Only the terminology for an alcohol meter combined with an immobilizer was presented differently.

In accident research and thus also in legal texts, the English term “Alcohol Interlock” has become established, which has been translated into German as “Alkohol Interlock”.

Our competent service staff is here for you and happy to answer your questions:

Just give us a call – we are here for you. Telefon: +49 (0) 4822 3673 314

Or you can send us an e-mail. E-Mail:

We will then gladly name one of our local partners, who will also ensure a smooth installation process.

An alcohol ignition interlock consists of two important components:

A handheld device as a breath alcohol measuring device with the integrated alcohol measuring technology, a control unit with an additional data memory and the interlocking technology to prevent the engine start.

Some immobilizers have an additional external relay that is triggered and prevents the engine from starting.

For hygienic reasons, a mouthpiece is inserted into the hand-held device through which the breath sample is delivered.
Depending on the device type, each operation is recorded in the data memory of the handheld unit or in the memory of the main unit so that they can be evaluated later.

First, the driver turns the ignition key so that the ignition is activated by the vehicle. The hand-held device indicates that it is ready for operation and the mandatory administration of a breath alcohol test is displayed.

The driver now gives a breath sample via a mouthpiece on the handheld device, just as it works with the police rapid test devices.

After about 5 seconds, any breath alcohol content is displayed. If this exceeds the legal maximum (preset in the system), the ignition is blocked. This is to prevent driving a motor vehicle under the influence of alcohol.

Driver error is still the most common cause of accidents on the road. In addition to inappropriate speed, risky overtaking maneuvers and disregard for the right of way, many accidents are also due to driving under the influence of alcohol. The use of so-called alcohol interlocks can help here.

Accident research figures show that alcohol in road traffic is still a major source of danger.

One way of counteracting this risk of accidents, among many other measures, is media campaigns against drinking and driving and a zero alcohol limit regulation. In particular, this includes the use of alcohol interlocks.

The calibration intervals for alcohol immobilizers are specified by the legal framework. Currently, calibration must be performed every 12 months.

The alcohol measuring units in the handheld units of alcohol immobilizers are highly sophisticated and very accurate measuring instruments.

In order for these to be able to determine reliable measured values for each breath sample, the units must be regularly cleaned and checked for their measuring accuracy. Since the measurement results must also comply with legal framework conditions and may also be used in part due to court orders, regular inspection and maintenance of the measurement units is indispensable.

Before the breath sample, make sure that you have not eaten or drunk anything for at least 10 minutes beforehand. Optimally, rinse the mouth and throat with water so that the breath is free of other particles from the mouth and throat.

Do not eat any spicy or mentholated sweets for at least 30 minutes before the breath test, nor any food containing alcohol, such as chocolates filled with alcohol.

Do not use disinfectants, windshield washer fluid or de-icer spray directly before the breath test, as these can release alcohol particles into the ambient air and thus into the breath.

Breathe evenly and calmly into the mouthpiece as soon as the hand unit prompts you to take a breath sample.

The measurement of alcohol on breath involves very small and very small particles of alcohol in the breath.

Alcohol content as low as 0.01 per mille can be measured, which corresponds to only a few particles in the breath. Thus, substances similar to alcohol or substances in the air that behave similarly can also have a negative effect on the test result, such as window cleaner containing alcohol, which can enter the vehicle through the ventilation.

Scent fresheners in the vehicle, disinfectant on the hands or used for surface disinfection in the vehicle, as well as freshly applied perfume, are also part of this. Spicy lozenges such as Fischerman’s Friend or menthol candies, as well as mouthwash, can also negatively affect the breath test.

Even tiny particles of alcohol or alcohol-like substances in the air inside the vehicle can negatively affect the breath sample. These include:

  • Disinfectant on hands, clothing or vehicle surfaces.
  • Window cleaner with alcohol, which after spraying penetrates into the vehicle interior through the ventilation.
  • Fragrance fresheners which were sprayed in the vehicle.
  • Fresh or extensively applied perfume.
  • A heavily intoxicated passenger.

Ventilate the vehicle interior extensively for several minutes and perform the next breath test with the windows or doors open.

Spicy lozenges, such as menthol candies or Fischerman’s Friend or even a chocolate with alcohol content can also lead to an adulterated breath sample. Rinse the mouth several times and extensively with water until the breath is again free of any substances mentioned.

Breath alcohol immobilizers approved in Europe detect whether a human breath sample is involved or whether the air stream is delivered by other mechanical air streams.

Human breath samples have well measurable breathing patterns and are thus also clearly identifiable as human breath samples. Other airflows, which are delivered to the measuring device as a fictitious breath sample, can very easily be identified as manipulation.

A detected manipulation is documented by the main unit and can later be identified as a manipulation attempt when evaluating the device data.

Especially in the case of legally ordered alcohol immobilizers, several recorded tampering attempts can lead to an extension of the order.

Thus, it is strongly discouraged to try this even just for fun!

Alcohol immobilizers are hygienically unproblematic, since each driver uses his own interchangeable mouthpiece.

The mouthpieces can be repurchased inexpensively; they are also designated as disposable mouthpieces. For sustainability reasons, however, it is advisable to use a used mouthpiece several times and to rinse it regularly with hot water.

As soon as a mouthpiece shows signs of contamination, it should be replaced immediately with a new mouthpiece.

The brand Prelock is composed of “Pre” of the English term “preventive” and the English word “lock” .

Thus, the sensible translation for PreLock = Preventive locking – by a breath alcohol test.

Our competent service staff is here for you and happy to answer your questions:

Just give us a call – we are here for you. Phone: +49 (0) 4822 3673 314

Or send us an e-mail to:

Please visit also our internet presence of: TruckWarn

Read more about our PreLock 90 right now:

Alcohol immobilizer PreLock 90

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