My back window, the one in the tailgate, has a mind of it’s own lately. The problem is that it rolls down on its own a random times. I rolled it up twice yesterday and found it rolled down an hour later both times. This condition seems to be affected by the sun. When it is cold and cloudy it happens much less.

When I bought the 4runner the window didn’t work work at all. The owner told me the window regulator box needed to be replaced. I picked one up at a pull-your-part wrecking yard for $25. When I took the interior cover panel off of the tailgate I found that the box was unplugged. I replaced that box with the one I purchased, buttoned things up, and was pleased to have a working window.

That was when the window started its random operation. It then made sense to me that the former owner had left the box unplugged because he was probably experiencing the same problem.

The problem gets worse when the sun is shining on the tailgate warming it. It will also do it when I open or close the tailgate. This make me think that the problem is due to a fault in the wiring.

So the question is do I have two control boxes with the same problem, or is the problem due to something else, like a short in the wiring?

You probably have partially severed wires going from the body to the hatch. You need to investigate. This video will help you out.

More than likely the wiring harness for your tailgate has some cracked/broken wiring, not uncommon after many years of opening & closing the tailgate.
Fortunately there’s a video made by Timmy the Toolman that addresses this exact issue.
Rear Hatch Wiring Repair (3rd Gen 4runner) - YouTube

I guess I just beat you with my post. Thanks for mentioning my video.

Tim your videos have helped and encouraged me countless times and I appreciate all the time and effort you put into this site to help the community.

Thanks to everyone for pointing me in the right direction on this issue. I am amazed again at the richness of Timmy the Toolman YouTube video resource.

Sounds like a circuitry issue. Can you recreate the problem by your own will? If so put a test light or multimeter on the connector to that controller box. That's if you don't see the problem in the harness boot. Someone the other day had a similar problem with battery voltage pulsating at that connector.

I had a similar problem with my first 4Runner. I would come out to the rear window being rolled down with no rhyme or reason. I thoroughly inspected the wiring harness between the body and rear hatch but never found any problems. What fixed it for me was gluing the rear hatch button part of my key fob to where it couldn't depress at all. Maybe it was a coincidence, but it never happened again for the 15 months after I did that until I sold that 4Runner.

Whenever this topic comes up I repost my experience - (not broken wiring, not control box)
https://www.toyota-4runner.org/1471503-post5.html

@WrenchTech I had wires broken and not the insulation, diagnosing not always cut n dried easy to see.

@Bad Luck had pocket lint build up in fob buttons cause stuff.