Crazy 03 Aviator Error - Help, Pls!

[grendyll]

Hi, all! I'm new to the site, and I have an AWD 03 Aviator with K&N drop-in filter and Magnaflow exhaust. I have a really strange thing happening in my Avi, and I'm hoping someone might be able to help.

I live in Dallas, and, as I'm sure you can imagine, it gets pretty hot here in the summertime - triple digits have been the norm for the bulk of the summer. This heat has brought out something really strange in my Aviator. When the external temp is 100 deg or higher, and the truck is started:

1) All gauges go completely crazy, running to the peak of measurement and falling again.
2) Every once in a while, the gauge backlight cuts completely out. When this occurs, the radio loses power, as do the window controls. When the backlight comes back, the radio and window controls do, too.
3) After the backlight comes back, the mileage shows "ERROR", and the "OIL CHANGE REQUIRED" error message is displayed.

Here's what I've determined through troubleshooting:
1) No error codes are thrown that can be read via OBDII.
2) It's not the battery. I replaced the battery, which read bad, to no avail.
3) It has to be something located in the cab - it's related to the internal cab temp. If I use a window shade and leave the windows cracked, this doesn't happen. Also, once the internal cab temp drops by using the A/C, the error disappears.

I know, I know, it's hard to picture all this. To help, I was able to capture a couple of videos (sorry for the poor quality):


http://www.vimeo.com/14157046

http://www.vimeo.com/14157275


Help! I'd love to get this taken care of! Anyone out there have any ideas?

 

[Mechanicboy]

That's crazy. Well a computer must be overheated. How long does this problem last? Does it change(last longer or shorter, get worse or better) when the A/C direction is changed, i.e from defrost or floor instead of panel?

 

[grendyll]

Thanks very much for the reply!

The fault typically lasts about 10 minutes or so. I've tried changing the A/C to floor from vent, but didn't leave it down there for an extended period - since this only happens when the cabin temp is over 100 degrees, we couldn't stand to leave it down there! Once the cabin cools off considerably, the fault goes away.

I did some other checking yesterday by testing all of my fuses with a test light while this was going on. I thought the fuse block could be distorting because of the heat - read about it on another forum - but all of my fuses were solid, and were not flickering at all. That tells me that the issue has to be past the fuse block in terms of wiring.

In addition, yesterday I started getting random error messages about the TPMS while this was happening; they were something like "TIRE PRESSURE SYSTEM OFF" or something like that. It flashed quite a few times nearly back-to-back, like the TPMS power was being interrupted.

That being said, there's a rather large wiring harness just near the fuse block. I don't know if it was just wishful thinking, but when I wiggled that, it seemed to make the needles jump more. I don't know anything about that connection, though.