A few of my rear defrost lines aren't working...specifically, the bottom four, and the 6th and 7th ones. I've looked at the lines and none of them are visibly broken. Are any wired in series, or are they all wired in parallel? Like, if one line is broken, could that knock out another line, or would each line have to have a break in it somewhere?
Is there any way to test continuity on these lines? I'm sure they're coated with something and not live to the touch, because otherwise just touching them could conceivably cause a short?
If it's not an easy fix where could I go to have this done?