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The rear defroster on my 92 bird isn't working. The switch appears to be functioning properly. The light comes on and I can hear the click in the passenger side dash. When i look at the positive side wire on the rear hatch strut, it appears to have melted. The coating is burned and the terminal is dirty and possibly slightly corroded. When I connect the wire back up to the terminal, it still doesn't power up. I don't see any breaks in the wire. Any ideas? What would have caused the burning of the wire? Should I replace the wire or slice it above the burned area and replace the end? I read 10 gauge works well. What do you all think?
My project 91 has/had a burned terminal. Plan is to replace the burned connector, and clean up the mess so it looks good, and probably just leave the relay/timer/controller for the rear defrost disconnected. Call me crazy, but I don't drive thirdgens in ice, or snow, and I've never really had an issue in 2.5 decades, so I'd rather live without a functional rear defrost than burn the car down trying to use a feature I don't need.
The rear defroster on my 92 bird isn't working. The switch appears to be functioning properly.
Both ends of the struts are insulated from the car body via plastic grommets. Sometimes they wear through or chip/break and short to the cars body, which is at ground.
Check to make sure that they are still intact and functional.
Those leads started out life as some sort of copper braid. It was wrapped in insulating tubing that didn't fit tight or anything. The tubing didn't really seal out moisture intrusion.
Over time, the moisture makes the copper corrode; and as it corrodes, the resistance increases. As the resistance increases, it gets hotter and hotter when used. The heat makes it corrode faster, which makes the resistance increase more, which makes it hotter, which makes it corrode faster... not hard to see where this ends up.
I have successfully replaced it with very flexible #10 wire; if memory serves it was motor lead wire, with about 30 some strands and Hypalon insulation. I had some #12 with silicone insulation that would have worked well too if it had been larger. I used the BIG THICK BEEFY HEAVY-DUTY yellow slide terminals with a 90°end; NOT the little thin weenie joke yellow slide terminals that are just like the blue and red ones except with a yellow-sized barrel.
One side goes to ground. The other gets 12V and must be insulated. I can't recall which side is which but I think the driver's side is the 12V side, don't trust me on that though.
The 12V side grommet as described above is critical to the electrical function. The one on the grounded side isn't as critical electrically but still, it keeps the whole thing from rattling and sqweeeeeeeking.
Thanks all for the replies so far. I have not had a chance to work on the car yet however, I took a picture to show all of you what I am dealing with. Is this damage consistent with the issues previously discussed? Although I am not driving the car in the winter, there are the occasional spring and fall days when I would like the defroster working. Thanks again.
That's really funny, because if the visible red paint was green, I'd swear it was my project car. So, um, yeah, you could probably crimp a new terminal on the wire, and slip on a new connector shell, and it might not do it again... But I just cut what was left of the melted connector off the terminal and got a new shell, and I never intend to hit the rear defroster button again because I drive fast enough that I really don't give a rip about what's already behind me.
