2016 LS460 Cruise Control Issue

[tcarroll2]

I recently traded up from a 2007 LS 460 to a 2016 LS 460.  This new car has the radar controlled cruise control on it.  I use it primarily while driving in town because of all the dumb drivers.  It has worked great.  However, yesterday I was behind a car that kept breaking in front of me and the radar cruise did exactly as it had been designed to do.  However, on the last occurance the car in front of me was turning.  Normally it takes way too long for the car to accelerate back to the cruising speed so I help it out a little by pressing the accelerator manually (without cancelling the cruise control).  When I did this yesterday the vehicle accelerated just fine, but when I got to about 6-7mph from the set cruise speed I let up on the accelerator to allow the car to achieve the set cruise speed on its own.  However, once the cruise speed was achieved the car continued to accelerate on its own.  I had the cruise set to 48mph in a 40mph speed zone.  I finally had to cancel the cruise setting manually when the car reached 60mph.  When I resumed the setting the car began slowing down and resumed the 48mph set cruising speed with no further issue.

Has anyone else experienced this?  The car barely has 18,000 miles on it and is still under factory warranty.  Should I be taking this to a dealership, or is it just a fluke?

[1990LS400]

Dynamic Radar Cruise Control (DRCC) is not perfect.  We have it in all our vehicles and it sometimes gets confused and malfunctions in a variety of ways with the worst being hard braking for no apparent reason - that's when I clean off the radar unit and the grill lens ahead of it with a damp towel.

Even with the occasional issues, I absolutely love DRCC.  I had a rental car without adaptive cruise control last week and not having it drove me crazy.

I suppose you could complain to your car dealer about the malfunction but that never got me anywhere when I did.  DRCC does not make a car self driving - the driver still needs to be always ready to intervene.

[Les Lex 2018]

Totally agree with your assessment. I drove an 18 Rav 4 that acted exactly the same way as the 18 RX. My own solution to the nasty braking habit is this: Whenever I resume the use / change the cruise speed, I first rest my foot on the accelerator. If the vehicle attempts to brake, a very quick application of the accelerator cause the brakeing to cease.  The system goes back to normal predictive cruise.

That said:  I don’t recommend experimenting with any kind of corrective actions until you, the owner, fully understands the actions and re-actions of your cruise systems.  You are the captain of your ship. Know your equipments behavior, actions, and reactions...