On my 2003 Mustang GT, on the bottom of the rear window the last 3 or 4 defroster elements have ceased to function, the others work as they should. I’ve looked the elements over and can see no breaks in them, the two devices (I’m unsure of the proper term for them) that presumably put the electrical charge through the elements is are okay, I’m referring to the two leads that are either side of the grid. I cannot figure out why 2/3’s of the defroster is working and bottom few are not. And while this isn’t a critical issue, it is an annoying one. Any ideas would be much appreciated.
Get an Ohm meter on them and start tracing resistance…inch by inch if necessary.
MikeInNH is right. The failure(s) in the conductors could well be nearly invisible crack(s). Since the “the lower three or four elements” are not functioning, and since multiple simultaneous failures is unlikely, I’d guess that there is a crack in one of the vertical conductors (at the sides), between the power connection and the top-most non-working element.
For repair, there used to be little bottles of conductive paint that you could dab onto the crack. I guess stuff like that is available in automobile parts stores.
Post back if you want detailed instructions on using the ohmeter.
Thanks for the suggestions. I was able to find 4 breaks in the grid wires. After visiting Advance Auto, I used a “Defroster repair kit” with various chemical pads, sand paper and vial of some sort of conductive compound. Any way I repaired the broken areas to the best of my ability. When it dries I’ll test the repair with the ohm meter to see if it worked.