An interlock, an alcohol interlock device installed in a vehicle, is designed to control the vehicle's engine start based on the result of the breath test provided by the driver. Drivers who have an AF-i1 installed, and people who manage several vehicles, tend to assume that one device handles the on-screen guidance, the breath test, and the engine start response. In fact, the AF-i1 is a setup that uses a handset operated by the driver together with a control box connected to the vehicle.
Separating the roles of these two components makes it easier to decide what to check first and how to describe it when the device responds differently from usual. This separation does not mean the driver should open or replace parts. It is a standard for reporting the screen guidance and the vehicle's response separately, so that the installation or inspection technician can check that vehicle's configuration and records.
The handset handles the breath test and user guidance
The AF-i1 handset is the component introduced as a breathalyzer in the official product information. The driver provides breath through the mouthpiece following the guidance on the handset screen and checks the test process and the result display. The cradle is the component that holds the handset where it will be used inside the vehicle.
The handset does not simply display results. The official information includes a function that detects whether a person is providing breath directly, based on the temperature, humidity, speed, and strength of the breath. However, the fact that the screen turns on and guidance appears does not let you conclude that the vehicle connection and engine start control are also working normally.
In cold conditions, the time until the device is ready to test can vary. Official AF-i1 information explains that warm-up time can differ depending on temperature and previous test results. So it is best to record a case where the ready prompt stays on the screen and a case where the screen does not turn on at all as two different observations.
The control box links vehicle wiring and engine start control
The control box is introduced in the official product information as the central processing unit. It connects to the handset through a communication cable and to the vehicle through installation wiring. You can think of it as the component that links the test performed on the handset with the vehicle's engine start control.
The AF-i1 is designed so that the engine will not start if the test result exceeds a set value. However, the fact that the engine did not start after a test is not enough to conclude that the control box is faulty. Test results and several vehicle conditions, such as ACC and engine start, may all be involved, so determining the cause component by component should happen only after the installed configuration and events have been checked.
Because the control box connects to the vehicle wiring, it is not something a user should disconnect or test by swapping in parts from another vehicle. Even a handset that looks identical may not be compatible with that vehicle, and its setting status is unknown. The scope of inspection needs to be set based on the model information and installation records of the installed device.
Why you should record the screen and the vehicle response separately
If you only say "the device isn't working" when you call for help, it is hard to tell whether the problem is at the test stage or in the vehicle's response. Separating what you saw on the handset from what happened in the vehicle when you tried to start it, in time order, helps the technician narrow down what to check.
| What to separate | What to look at on site | Information to pass on |
|---|---|---|
| Handset | Screen lighting up, guidance messages, test result display | The message shown and the test time |
| Vehicle response | Response of ACC and engine start attempts after the test | Order of start attempts and anything different from usual |
| Installed device | Model markings on the handset and control box, installation records | Vehicle identification and whether there was recent maintenance |
In a hypothetical case, suppose a driver completed a test following the screen guidance and a result was displayed, but when they then tried to start the engine, the vehicle responded differently from usual. The observation here covers "the time the test result was displayed" and "the vehicle response at the start attempt." Rather than interpreting this as a control box failure, one possible action is to pass on the screen message, the ACC and engine start response, and whether the vehicle was recently serviced, together with the model information in the installation records. The technician compares that vehicle's installed configuration with the stored events to decide whether inspection is needed. If the intended test and start flow can be reproduced after inspection, the check for this case is complete.
Stored events are data for confirming the order of responses
According to official AF-i1 information, the device can store not only test results but also interlock usage events related to vehicle ACC, engine start, and tampering, along with date and time information. The dedicated PC software is described as allowing events to be managed and downloaded, and usage behavior to be configured.
It is more appropriate to use these records as data for seeing in what order tests and vehicle responses occurred at a given time, rather than as data that immediately establishes a specific component failure or who is responsible. For example, a manager can require drivers to note the vehicle identification, test time, screen message, response after the start attempt, and whether there was maintenance just before. Linking on-site notes with stored events reduces the chance that a guess is passed on as if it were the cause.
The role split is a standard for daily use and inspection
The handset is the point of contact where the driver takes the breath test and checks guidance. The control box is the central component that connects the handset to the vehicle wiring and handles engine start control. Because the two parts work together as one interlock system, it is important not to settle the state of one side based only on what is seen on the other.
The AF-i1 is also described as having an inspection and calibration reminder function. If a reminder appears or test- or start-related symptoms repeat, the driver can first organize what they saw on the screen and how the vehicle responded, and then hand it off so that the installation or inspection technician checks the current device configuration and events. The purpose of using the names handset and control box correctly is not to do repairs yourself. It is to describe what actually happened without confusion.
