Toyota Yaris II (2017) Automatic Alarm Activation: Diagnosing Causes, Limit Switches & Reed Switch

How to diagnose the activation of the alarm without an external cause? I checked the limit switches in the door and under the engine cover. I didn't find the limit switch under the trunk lid. There is probably a reed switch or other sensor, but I have not located it, please hint.
Car details:
TOYOTA YARIS II HATCHBACK 3D 1.0 VVT-I (2017)
Type: XP9F (A)
Variant: KSP90 (G)
Version: KSP90 (L) -CGMRKW (1B)

Jerzy Pura wrote:

alarm activation without an external reason?

Disconnect all alarm triggering lines from the control unit and test in this condition.
Then connect the trigger lines and sensors to the control panel in turn - each time testing the system.

Jerzy Pura wrote:

TOYOTA YARIS II (2017)

There is no guarantee?

Maybe you have a broken glass sensor installed, and it reacts not only to the noise of the broken glass, but sometimes to a loud car passing by or the shrinking of shrinking plastic.

gimak wrote:

broken glass sensor fitted

The broken glass sensor (with microphone) will not react to a passing car or shrinking plastic.
Shock sensor (impact with piezoelectric element) is different

I have such a sensor and it responds to more noise. At first I was also wondering about such accidental alarms. The sensor reacts (as it is active) to a stronger knock on the glass or body. I don't know if there is any possibility of increasing the sensor threshold.

I noticed that the alarm went off in the garage without any noise, it turned off after a short operation. Such switching probably caused the battery damage and replacement. When activated, the alarm sounds like the door is open, but the central locking works and the door is closed. The sound phenomenon once occurred, once not, but now it is still there. Previously, I wrote that there is no limit switch under the boot lid. I think I will unscrew the plastics to find the sensor of opening the lid, because I have not yet located it.

In my garage, sometimes the alarm was triggered because it was signaled late when the alarm was deactivated.

Jerzy Pura wrote:

When activated, the alarm sounds like the door is open, but the central locking works and the door is closed.

One has no relation with the other. The alarm (control panel) checks the status of the sensors and reacts to this. In this case, one of the sensors in the door, boot or engine compartment has an uncertain contact or there may be uncertain connection in one of the sensor circuits.
Check your system voltage while the engine is running. Maybe the battery is heavily overcharged, and it can also trigger an alarm. At my old battery, sometimes the alarm was heard when the engine started (starter operation). After charging the battery, it was quiet for some time.

The reason for the accidental activation of the alarm was a malfunction of the boot lid closing sensor located in the tailgate. With the cover closed, the sensor should be in the "normally open contact" state, while with the cover open in the "closed contact" state - closed. The sensor's malfunctioning was that it sometimes got short-circuited when the boot lid was closed, probably due to shocks, and the alarm went off. I made the initial diagnosis by looking at the door opening indicator, sometimes it did not go out after closing the boot. After removing the plastic cover and unfastening the sensor cube, the defect subsided. After the leads to the cabin to measure the sensor, it turned out that the next time you open and close the trunk, the sensor is once closed, once open. I ordered a new lock on Allegro.
Thank you all for your interest in my topic
George