My new electric Heybike Cityrun has electric directional signals controlled by a switch on the left handle bars. I can't see the signals flashing while riding because of their position so I often forget to turn them off. My idea was to tap into the line between the switch and the signals. I'm a retired EE and know what I am doing.
The best place seems to be where there is a four pin plug-in connector set. It's made of two plugs that align in only one way to prevent accidentally misconnecting. If I can find some of these, I can insert a T-connection which I could then connect to a couple of LEDs mounted on the handlebar. (pic below).
I've looked at trying to put tiny mirrors on the lights which would allow me to see the sides of the headlight/turn-signal unit from behind but the lights are pretty small and I don't want to interfere with their visibility to others. I'm too unsure of riding at this point to use hand signals and can't control the bike well with one hand because of my age and not being comfortable riding again after a 50+ year gap.
FYI, the Cityrun was the top rated Electric in the recent issue of Consumer Reports.
John P