[denNorske]

I suggest you to do a debug:

pawn Код:

forward Damage(playerid);
public Damage(playerid)
{
    new Float:health;
    new veh;
    veh = GetPlayerVehicleID(playerid);
    GetVehicleHealth(veh, health);
    printf("--- DEBUG: Vehicle Health on \"public Damage\": %f", health);
    if(IsPlayerInAnyVehicle(playerid))
    {
    if(health > 800)
    {
        TextDrawColor(Textdraw13[playerid], 0xFFFFFFFF);
    }
    else if(health <= 800 && health > 500)
    {
        TextDrawColor(Textdraw13[playerid], 0xFFFF00FF);
    }
    else if(health <= 400)
    {
       TextDrawColor(Textdraw13[playerid], 0xFF0000FF);
    }
    }
    else {
    TextDrawColor(Textdraw13[playerid], 0xD3D3D3FF);
    }
return 1;
}

Check your log for values. If they are wrong, you must recheck your code for mistakes