Liquid level in the tank (pic. 37) with the cap installed, it should reach the lower edge of the filler neck.
If the hydraulic brake drive is in good order, the lowering of the fluid level in the reservoir is due to the wear of the linings of the brake pads. The lowering of the liquid level indirectly indicates their limiting wear. In this case, it is necessary to directly monitor the condition of the pads, and there is no need to add fluid, since when installing new pads, the fluid level in the tank will rise to normal.
The service brake system alarm indicator lights up when the fluid level in the reservoir drops below the permissible limit, which, with partially worn or new brake pad linings, indicates a loss of system tightness and fluid leakage. In this case, top up the liquid only after restoring the tightness of the system.
By pressing the pusher on the tank cover, check the correct operation of the alarm indicator of the emergency state of the working brake system - with the ignition on, it should burn with a constant light.