Check out this video. He has the same wiring as you do. Looks like it connects to red wire labeled "lock". You either modify the connector or splice it in. Make sure it works though before cutting anything.
Thanks for this video! I have watched it multiple times before, but I don't have a switch on my controller like this guy does on his controllers. My switch is tied into the displays power. This is actually the last electrical problem I'm trying to troubleshoot. I got my custom bike up and running, throttle works, voltage display works, motor works, all the lights working but I need to figure out how to tap into the ignition wire because the key function is useless at the moment. I tried Y splitter tapping into the ignition which is just a positive but that positive is also what powers the LCD display.
So basically I made a y splitter and it failed. The voltage display was on immediatly without needing a key and throttle still worked as well so idk, very strange. I'll have to keep messing with it
edit: ... actually now that I'm thinking about it. I think I may know the solution and I'll try it later.
All I should need to do is put my blue and yellow into a connector and the yellow feeds the blue the power when the key is turned, which will in turn also give my display power when the key is turned. I'm not sure I will see my battery voltage but I'm almost certain it should show me the battery voltage since it's the positive line.