If it's just the tail/brake light will be perfectly fine to jump, on my xr4i and my dads current xr4i I linked the rear fogs to the brake lights so as to have 4 brake lights cheap(20P) and easy to do.
The noise you hear is bcause the hazzard switch has not gone full travel, very classic problem when not used year to year, they jam, take apart CAREFULLY, and you can see all the pin connections that get bridged by the movement of the switch, clean the crap out, which is old stiff grease, clean up then put a little beeswax of if none use a furniture polish that contains it spray liberally over the surface which the switch bit slides, will be good as new again.
tabetha