[Jeffry]

pawn Код:

public OnStateChange( playerid, newstate, oldstate )
{
    if ( newstate == PLAYER_STATE_DRIVER && GetPlayerVehicleID(playerid) == passwordedVeh )
    {
        ShowPlayerDialog( playerid, 777, DIALOG_STYLE_INPUT, "Error", "This vehicle is passworded, enter the password!", "Use Vehicle", "Exit" );
        TogglePlayerControllable( playerid, false );
    }

    return 1;
}

Should work then.