You MAY have it disconnected if you can't FEEL it - but for the most part you WON'T hear it - that's why it's called a SUB-woofer - it plays sound often at or below your level of hearing - but you should certainly FEEL it. It will be more a vibrational sensation than a vibrational shock though, because it's moving air not banging on metal surroundings. Most cross-overs to a sub-woofer are at about or below 100 Hz. MOST folks won't hear these sounds - but many youngsters can. Below 20 Hz it's VERY difficult for humans to 'hear' these but they can be sensed or felt - and not merely by the shaking and rattling of other stuff in and or around the car...
You dealer can scope the outputs to/from the sub and see if it's working correctly -
You dealer can scope the outputs to/from the sub and see if it's working correctly -