mediumfast

Well it's fixed. The problem ended up being an electral connector near the back of the truck. We plugged into a friend's trailer and all lights worked properly. We then unplugged the wiring harness (rectangular grey) at the rear of the truck on the frame rail and tested the female side. We had power where we were supposed to so at that point the problem was isolated to the back corner of the truck. The problem ended up being a bad plug. We had power on one side and not the other....Probably very uncommon. Nothing showed any signs of breakage, corrosion, anything out of the ordinary. I jumped the bad pin and soldered both ends, retaped everything and for the first time since November my truck work right!!
I appreciate all the ideas people shot at me.

Now...I need to get new mirrors. Ive seen some aftermarket ones (Tyger) that have everything I want except the seem to be sold out. They even have the turn signal on the front of the housing which I like. I like the look of the 09-newer side mirrors but I don't know if they 1) fit on 04-08 trucks, 2) have the same plug and wiring.

Wesman1

Hi there. I just had the same(ish) experience and spent a few days tracking and figuring and wasting alot of time as well. My truck also had hyperflash, which typically means a bulb is out--but alas no. All bulbs were good. Then the next day as I was driving home from work, BOTH sides went into hyperflash and I lost illuminocity to my entire rear--all bulbs went dim. When i took a bulb out from one side, the other got brighter. I searched far and wide on so many of these threads, got some good places to start but there was one dude that had it right. He had a 97 Ford but he nailed it. I did the whole, check the fuse, check the relay's, check the fuses under the hood, check the fuse panel (junction box) for water corrosion and finally there were many threads on the multifunction switch as being the problem--I have mechanic friends who even said that was it--$180 later!!!--so frustrating! Nothing worked until I took a test light and traced every plug--i found 2 things. 1) the main group of wires that leads down my box connects to the fuel pump circut board--that was terribly corroded and causing a short (I have pic's on my profile) and 2) there are two main plugs that follow right after that fuel pump circut board that lead directly to the rear lights themselves--both of which were corroded from the elements and needed a good cleaning and some circut grease. (Also--see the pic's). Those 2 effing plugs, created a short in the ground wire and what I found out from scotty Kilmer was a bad ground can make your vehicle do weird things to the taillights--and that was abundently true. So instead of $$$$$$ repairs--try the cheap stuff first. Fuses, relays, and contact grease on the plugs themselves, then move on to the more expensive stuff. Good luck!

P.S. Im not on here often and I don't check messages often nor do I have any clue how to put this as a new post or thread. However, this is a million dollar time, effort and money saver fix so if there is anyone who wants to cut and paste this post and my pic's to help others--please do them all a favour.

All the best!