Several times I've been sitting in traffic or a drive-thru line and heard what sounds like an alarm chirp - just a single chirp. It took a few occurences for me to determine that it's coming from my vehicle and not some other knucklehead playing with his alarm. I've never heard it while driving over 10mph (ish). I've searched the CL forums and don't really see anything that looks like this. It's on my list for the 5K service. I haven't talked to the dealer SA yet. When I take them intermittent problems like this I like to try and work it myself for a bit. And I'd love to walk in there and tell them what to look for. So I'm tossing this one out to the forum to bring the awesome powers of collaboration to bear!

It is not the same sound as Park Assist, which was my first thought. That's more like a beep than a chirp (that should remove any doubt about what it sounds like!). I also don't believe it's part of the anti-stealth modification for the 2013 because folks have described that as more like a low growling noise.

Ideas? As we used to say in the software business: Is this a "bug" or an undocumented "feature"?

 

As a software developer myself I would say it is an "Undocumented" feature.

I have no idea what that is and never happened to me (YET). Please let us know what that "Feature" is once you found out.

 

Hill-start assist? How hard are you pushing brake pedal?

 

^^ Good call ... and easy to check; a hill holder indicator light will come on in the dash. It happens when the car is stopped and you further press the brake pedal.

 

I thought of that too but it doesn't chirp over 10mph, only when applying force to the brakes while stopped.

 

It does beep once when activated, twice when cancelled. Since it is a braking function, unlikely to hear it when moving. Or at most you might hear it below 10 mph as Texas and Cruiter have indicated as it cancels. Of course as UCSB states, the indicator light is a dead give away.

 

Hill-start assist? Is that something new in 2013? Didn't know I had that feature! Another thing we used say in the software biz was that if people would RTFM they could find the answer for themselves (sigh) - guilty. I just never imagined this could be a feature. Thinking about being in a drive thru line, I likely do push on the brake as I reach in my back pocket to take out my wallet (ding!) or don't know I'm activating the feature when I grab the rag under my seat to wipe a smudge off the windsheidl (ding ding ding!). I can say that I have not noticed a dash indicator but I'll definitely be checking that out tonite and report back tomorrow.

 

I don't see hill-start assist on the sticker. And I've tried several times to activate it with no luck. Do all 2013 vehicles have this feature?

 

It was a standard feature on the '10-'12 models, not sure about the '13. Maybe BertL can chime in. To activate it, drive up an incline and step hard on the brake. You should hear a beep and see a light on the dash. IIRC, press the gas to release. I only used it once when I was stopped by a train while going up a snow covered hill. I couldn't back up because a car was behind me. It worked like a charm. Hope that solves your beeping mystery

 

Texas,

Im sure you've found it in the manual, page 341
http://drivers.lexus.com/t3Portal/do.../sec_02-04.pdf

The feature self cancels. Press down on the brake pedal, extra hard. It beeps, indicator lights and brakes lock for the amount of time it takes you to move your foot from the brake pedal to the accelerator pedal. Brakes release and it beeps twice. I would think it's a short timed feature to prevent you from engaging and mistakenly thinking you have the car in park, engaging, opening your door getting out and then watching your car roll away when the feature cancels

I'd need to dig up my window sticker to see if it was listed as a standard feature '10-12.

 

Anita, if you can only activate it on an incline then it's not the HAC that's beeping. There are very few hills in the Houston area - close to the coast and very flat. That's why torrential downpours cause flash flooding. The best "hills" around here are the entry/exit ramps off the major freeways...probably not a good place to test this feature!

DunWkg, I looked at the manual (pp 341-342) and wondered if the incline was required. It does not list that condition under "Hill-Start assist control can be operated when" on p341.

 

I wonder if the chirping is the Vehicle Proximity Notification System they have for the hybrid.

"When the gasoline engine is off, a sound is produced to warn pedestrians, people riding bicycles or other people and vehicles in the surrounding area that the vehicle is approaching. The pitch of the sound adjusts according to vehicle speed. When the vehicle is approximately 12 mph (20 km/h) or more, the warning system turns off."

 

Good idea, but I ruled that out when the OP said he was sitting in traffic or a drive thru lane... The sound of the vehicle proximity monitor on the RXh (and Prius) is continuous when the truck is moving, and not a single chirp that he heard. Now, if the OP had said he thought a UFO was landing nearby, well, THAT would be the sound.

 

Hill-start assist, at least on '10-12, works on flat ground and both when in drive or reverse. Wouldn't test or practice in garage.

They have UFOs in Texas, too?

 

Could be radio interference from the wife's tracking device .