[UPDATED, still need urgent help] - Automatic headlight mod causing "Check Headlight System"

I have performed the automatic headlight mod. I used pins from L66 and L8. I purchased the stalk from eBay, and have it successfully installed. The mod functions; with the stalk set to AUTO in darkness, the lights come on and the dash dims properly. The lights also perform the opposite function in daylight. However, about 10 seconds after headlights are activated automatically, an error shows up on the dash. A flashing yellow triangle appears on the left, and the message "CHECK HEADLIGHT SYSTEM" appears. I am a novice at this and made a mistake by swapping the pins 21 and 28 the first time when I installed the pins in L7. I realized my mistake and corrected it, but this error is befuddling me.

EDIT: this issue also is occurring when the headlights are simply set for "on" instead of "auto".

It may be of note to mention that I also removed and disassembled the instrument panel (don't remember what it's called). I noticed that the repair manual indicates this error message could be from the gauges as well (if I read it correctly). I needed to clean the screen of the panel from the inside because the previous owner had caused scratches on the inside of the acrylic.

I am sorry for creating a new thread on this, but I can't help wondering if I have really messed something up. Please help.

 

A couple of things I checked:
It's not the stalk. I disconnected the new stalk, and had the old one attached, just hanging there. The error still occurs.
It's not the sensor. I had a wire nut connecting the sensor wire from the dash to L7 for easy removal if I needed to lift the dash again. I disconnected it, and the same error occurs.

Any ideas? I am beginning to wonder if the problem is nowhere near what changes I made for the mod.

 

No, it's the addition of a Canadian headlight stalk, a wire from the light sensor already in the dash, and a wire to the new stalk. That's it. It should be an easy mod except you have to take the dash apart to get to the connections, and you have to order pins or sacrifice pins from existing unused connectors.
Here's the thread (warning: it's huge): Automatic Headlights | PriusChat

If you want to do the mod yourself, the main information is in this post: Automatic Headlights | Page 12 | PriusChat

 

I have now found the cause of the check headlight system error. I had misread some information in the automatic headlights mod thread. I thought only the people who had a solar roof needed the L8 connector, so I sacrificed my L8 connector to get the pin connectors needed for L7. The problem is that I have a Prius V, which has LED headlights, so those pins and wires are actually needed. Therefore, I need a new source for connectors in L8 that can attach to those pins in the ECU. Can ANYONE tell me where to get connectors that will attach to those pins? I have been driving around with this error on my dash whenever my lights were on for months now. I am ready to get rid of it!