I've had this Prius for almost 3 years and I've never noticed this button. It resides just to the right of the hood release. Any ideas?
Judging from it’s out-of-the-way position, I would venture a guess that its part of an after market alarm system.? To say the least, from an after market accessory of some sort. Most certainly it is not a stock configuration.
Hmm....well I think I may have found out what it is. This thread on another site says it's from a KARR alarm system: http://www.toyotanation.com/forum/122-highlander-2nd-generation-2008-2013/1422146-what-s-button-under-my-dash.html
Agreed. Unfortunately, they violated the #1 rule in after-market installation which is: "drill no holes; a good install can be returned to 100% OEM." Considering the number of unused blanks on the dash, it's surprising.
Some dealers put the KARR system on early gen 3's to protect theft off the lot. It has a few more bells and whistles than the OEM alarm: Motion detection with "warn away", shatter sensors for glass breakage, rolling codes and valet mode. Here's a writeup on how it works: (If it ain't broke, don't fix it!) Re-programming KARR alarm Make sure Karr is disarmed (no LED lights) Turn Prius on Press and release Karr button 3 times Short LED light with 1 short horn Before 3 seconds, turn Prius off Horn will give a short-long chirp Within 3 seconds, turn Prius back on (now in programming mode) Horn will give a long-short chirp Press Karr button one time per option (there are 4 options) the Karr LED will flash the number of times per option you are on. Option 1 (one flash): wait ½ second and horn should chirp once (auto-lock with ignition on) Option 2 (two flashes): wait ½ second and horn should chirp once (auto unlock with ignition off) Option 3 (three flashes): wait ½ second and horn should chirp twice (passive arming and lock without lock) Option 4 (four flashes): wait ½ second and horn should chirp twice (active arming) Turn Prius off to exit programming. Get out and arm…LED should flash. Wait a bit and then attempt to disarm with fob. Valet mode – car on, press and hold for 5 seconds until solid blue LED Valet mode off – within 3 seconds of Prius on, press and hold until LED off