Having had a 2L Hybrid hatchback (excell) for a month i have just about got used to all the knobs, switches, bings & bongs. Most of the noises it makes i hav managed to tame, suppress or control but for some reason  i get an alarm with three bongs. Nothing shows on the display and i am not aware of any problem. Its the same sound as when lane assist is on and you cross the line without indicating. But it occurs if lane assist is off. I have googled "Toyota 3 bongs" without success.