Well... this hack is just the best. Something so simple. Ever since I bought the PHEV ive looked at that blank button and thought . . it must do something. I just never got round to playing with it .. . until today. My main reason for doing this is because I got a new phone and no matter how hard i tried i couldnt get it to connect to the car.
This Mod took me around 20 minutes and I used the standard fob case. The only thing I bought was a couple of switches.
So first of all I stripped down the fob and soldered on a new switch. Its a little fiddley but just take your time, cover the rest of the board with something just to stop any solder splatter that may jump off the iron.
I then removed the blank in the fob and cut down the 3 or 4 tiny bumps.. . the ones that are all in a line. Dont touch the two taller retaining clips.
I then cut down a small pice of WD40 straw and glued it onto the blank. I had to trim it a little more than whats on the picture I think overall its around 1.5mm long.
Next. .. make the hole in the fob case match the one on the other side. (take the 'off' button out to compare).
Put it all back together and see if it works.
So just for info my car is a 2016 GX4H.
Before I attempted this i made sure the switch would actually work by dismantling the fob, holding the battery onto the board and shorting SW3 with a screwdriver (double tap).
The car was plugged in and UNLOCKED. When the lights flashed the car also locked but the mirrors did not fold in. (not until the actual lock button is pressed).
I couldnt hear or see anything happen at first but then I remembered . . i have a in home energy meter thingy so i can see what the house is using. I looked at that and sure enough there was a draw on the system becasue the car was heating up. If i wouldnt have seen this Id never have known it worked, unless i waited 15-20 minutes.
I think it would run until the battery runs out. I do not think it would start the car simply cut out. If it did run the engine, it would as far as i know would be illigal to leave a car unattended while running.