While I've had stable behaviour with a previous set, the most recent set that I just put on my 690 is acting up.
Sometimes it (the single button controller) repeatedly flashes with all 4 lights illuminated, at which point I have to shut it off (hold button on for approx 3 secs). Then I press the button again (hold for approx 3 secs) to turn them on, and they're fine, allowing me to select any of the modes (1/green, the least amount of heat, 2/yellow, the next level up, etc...).
I've also had them shut off on their own, ie: if I'm riding away while on #2 (nice toasty setting), I'll slowly notice my hands getting chilled, look down and notice it's turned itself off !
I've actually got a spare kit, and am going to try the controller from the other kit to see if thats whats defective....