23 Keys, locks and alarm system ›  Alarm system A trailer is integrated into the alarm system under the following conditions: If the vehicle is not unlocked for a longer period of time, the function can be deactivated automati- cally. Disable the alarm before connecting or discon- necting a trailer. If the electrical connection to the trailer is interrup- ted on a vehicle with an activated alarm system, warning signals are triggered. Troubleshooting The vehicle cannot be unlocked or locked using the sensors on the handle Settings When the ignition was switched on, no key was found ✓ The vehicle is factory-fitted with a towing device. ✓ The trailer is electrically connected to the vehicle via the trailer socket. ✓ The trailer is not equipped with LED taillights. › Lock or unlock the vehicle with the button on the key. › Then try to unlock or lock the vehicle using the sensors on the handle. › If keyless locking does not work, seek the help of a specialist garage. ▶ Interior monitoring ▶ Towing protection › Insert the key into the vehicle. ▶ By double locking within 2 seconds. ▶ In infotainment in the menu  Menu item for interior monitoring ▶ In infotainment in the menu  Menu item for interior monitoring ▶ Opening the bonnet ▶ Opening the boot lid ▶ Opening the door ▶ Manipulation of the ignition lock ▶ Towing the vehicle ▶ Movement in the vehicle ▶ Sudden and significant voltage drop of the electri- cal system ▶ Uncoupling the trailer ▶ Opening the door unlocked via the lock cylinder › Turn on the ignition. › Unlock the vehicle. For the correct functioning of the alarm system, all windows must be closed. Or: Operating conditions Switching off the triggered alarm Alarm triggering Alarm system Functionality Deactivation illuminates Message that no key was found in the vehicle The following functions of the alarm system can be deactivated at the same time: Deactivation will also switch off the SAFE func- tion » page 20,  Functionality . Or: The alarm system triggers audible and visual signals during a break-in or towing attempt. The alarm system is activated automatically approxi- mately 30 seconds after the vehicle is locked. The alarm system is automatically deactivated after the vehicle is unlocked. Or: The activated alarm system triggers an alarm when one of the following events occurs: The deactivated functions are reactivated after the vehicle is unlocked and locked again. Deactivation is to be carried out if the vehicle is, for example, towed or transported.