That would be my guess.

Hmm...same year as mine.:confused:

Search windshield refraction. Some of it suggests the light beam is the result of accumulated micro sand/debris pitting. If so, polish or replace.

That, since he says his windshield is clean, then it's due to scratches. In the pic, you can see that the line in perpendicular to the scratches made by the windshield wiper which points to the issue being those scratches.

This is why I replaced my Taco windshield. What a difference!

When I first got the car and noticed it....I realized that the lower end of the 'light cable' was always hooked to the drivers side headlight...even sitting in the passenger seat.
Made me wonder if something in the drivers headlight was bent and reflecting the sunlight into the windshield. If that were the case, I would look into replacing that one.
I don't know how it could do that, but it's puzzling.

You guys are killing me with all the theories. It's the wiper.

I had a crack develop on my old jeep and the plastic between the glass did almost exactly what you have. the crack never grew but the discoloration did. I think it was the plastic between the glass panes got oxidized.

Find a similar Fit and test drive it in a similar situation.

I asked on the Fit Freak Forum...there were no similar experiences. (the forum is like this one)
I have not driven another 2010.
Yesterday, after reading on here about how it had to be exterior dirt or scratches, I took about an hour of scrubbing with magic eraser over and over, trying to remove any dirt or streaks.
This morning, I drove it east (into the sun) and the 'light cable' was more pronounced that ever. It's definitely not dirt.

You might have micro scratches from using the magic eraser? I'd get one of the windscreen polishing kids and go over it.

The 'light cable' was there before I ever used the erasers

With some patience use Bon-Ami and sparing amount of water with a soft sponge on the outside glass. It won't scratch the glass, but will lift out the dirt and oils from the pores of the surface. It works. Also FYI, non OE windshields are not ground ( optically ) as finely and accurately as the manufacturer version.

^^^ I did that with the 'erasers'....no difference. It's an OE windshield.
Happy to listen to any possible answers to this problem.
Thanks

Clay bar then polish. If it is still there after buffing it is probably inside, between the layers. Maybe the glass and plastic have delaminated in that area.

I have scoured and cleaned both the int and ext of the glass. All it does is make the 'light cable' more bright. It's definitely not a cleaning problem.
If it's a glass layer problem...I may just live with it. Not worth replacing the windshield with 230K miles on it.

I'd either just replace the windshield, or live with it.

^^^ With the mileage on the car....I'll prob just live with it.
The car is a great, fun driving car. I really enjoy how it drives. But, with 230K miles, I know it's days are numbered.
It rips through the gears and still gets 40mpg. Never owned a car like it.

That would be my guess as well.

The Fit has a large square windshield.
Chassis flex may concentrate that load into a certain vertical line point after a decade.
(Right turns more than left turns.)
That might create just enough flex to separate the sealed layers ever so sightly, but not enough to create an obvious blemish.