Just watched, or re-watched, a few AK 550 review videos this morning that showed the heated grips function. Turning on and off. And noted that the LED indicator on the left grip is in fact the same as mine is. I was certain I remembered the entire oval was evenly lit up but I guess not. Maybe just the "new bike" fever that was happening at the time. One of these videos was from Bike Trips from 2018 that showed that owners bike after getting the heated grips replaced with the new and improved (in 2018) version. His bike was an earlier model that did have the issue with the grip material being too soft and defective so that it started to fall apart in the summer heat (without turning on the heated grips). He had put electrical tape on his grips until the new grips were installed and he reported that the new grips are far superior to the previous ones. But my point here is that the LED indicator on the left grip also lit up the same as mine... IOW, the actual LED light element is in the lower end of the light oval so it is bright at the bottom and gets dimmer toward the top of the oval. I also noted on that video that the LED indicator very slightly flickered or wavered just a little as he was riding along the road. Again, just like mine does. So I know that part is working normally.
My ride yesterday I used the heated grips only, without using my heated gloves. I wore those gloves and had them plugged in but did not turn on the gloves heat controller so they were just being passive gloves. I sometimes do that anyway when temps are in the upper 30s F since they are a bit warmer than my non-heated winter gloves. The heated grips worked flawlessly the entire ride yesterday. Wondering if the extreme cold of 12 F was to blame for the heated grips system fault or if using my heated gloves at the same time as the heated grips caused an issue due to power through the wires of the gloves or extra glove heat being sensed by the heated grips system (as in too much heat for the setting selected).
Will be doing more of that kind of testing in the next few months. This month looks to be too warm to really test that out well but January and February usually give us some really cold temps from 15 F down to below zero F. If it does turn out to be the heated gloves causing an issue I hope to resolve that by using handlebar muffs instead of the heated gloves. If the extreme cold is the cause of the issue I'll just have to avoid using the heated grips during extreme cold and only use them between 20 F up to 40+ F. And then I'd only use my heated gloves for the extreme cold temps. Though it seems that there should be no issue with the heated grips control box working in very cold temps since all other electronic "boxes" on the bike work fine at those temps. Also, if it is the extreme cold causing an issue with the heated grips controller I would have expected the heated grips symbol on the dash display to flash, but it didn't. The dash display flashing is supposed to indicate a controller issue sending the signal to the dash display, and the red grip light flashing indicates a handlebar heater issue if I understand the manual properly. The dash display has not ever been flashing... yet.
The owner manual does suggest to go to a Kymco dealer for a check up if there is a handlebar heater issue (consistently). Pressing the heater button stops the red light flashing and shutting off and restarting the bike resets the heater system.