Definetely yes, as i usually make antenna for my modems just to save the cost of antenna, few times i got faulty antenna with module, so when nothing works there is no harm in trying something which is a ray of hope. definetely it will not harn the module.
With multimeter you cannot find out as there will be a small coil at the antenna or it has very low impedance, multimeter will show short in any case. you remove or keep antenna, it shows low or zero resistance, you cannot check it with multimeter