Today my daughter was driving my '14 LS 460 AWD on a road with some steel plates. Her speed was about 30 mph. Pre-crash system of my Lexus suddenly activated without any reason (maximum break strenght, seat belts also tightened) and completely stopped the car. It was quite scarry. I did some research on the Internet and it looks similar to a known issue with 2013-2015 Lexus ES/Toyota Avalon (resolved by a recall).
Does anyone here have a similar experience?

 

This is scary!

Can you give us a little more details about the location of these steel plates on the road?

I have PCS on my two 2010 460Ls and never experienced this behavior, including 70+mph driving on narrow curved bridges with concrete barriers on both sides.

Hopefully you are still under warranty and can get the dealer to check it.

You might need to consider disabling PCS at the meantime, there is a button under the dash

 

That's my thought as well. Where were the plates on the road?. And how big were they?.

PCS uses millimeter wave radar to detect objects in front of the sensor. Its designed to detect metals and steel plates would fall under that category.

From Lexus :PRE-COLLISION SYSTEM3 WITH PEDESTRIAN DETECTION6 MAY OPERATE IN THE FOLLOWING CONDITIONS, EVEN IF A COLLISION IS NOT LIKELY:

1. When there is an obstacle or parked car at the point of entering a curve, in a curve or at an intersection

2. When passing through a narrow steel bridge or through a low ceiling area like a tunnel or parking structure

3. When there is a metal object or protrusion on the road surface or items dropped onto the road

4. When passing an opposing vehicle when turning right or left or passing an opposing vehicle around a curve

5. When driving on an uneven road or in weeds

6. When suddenly getting close to another vehicle that is driving ahead

7. Upon seeing a raised intersection, sign or advertisement board/vinyl in front of the vehicle

8. While driving up or down a slope, where metal such as a steel plate (manhole cover) is in front of the vehicle

9. Reacting to Electronic Toll Collection (ETC) bar when passing through an ETC gantry

10. When sensor direction is offset due to a strong impact near the sensor

11. When passing under a bridge or narrow tunnel

12. When turning around a curve where there is a pedestrian to the front of your vehicle (on a sidewalk)

13. While passing near a pedestrian or through a group of pedestrians

14. If a pedestrian suddenly crosses in front of your vehicle, or suddenly stops while crossing

15. When passing a leading vehicle or when a leading vehicle turns to the left or right

16. When passing through parked cars or driving between vehicles

17. When driving on a narrow road with roadside guardrails, telephone poles, trees, etc.

 

I had this happen on my 2014 Jeep Grand Cherokee Overland with a similar system. It is quite scary.

 

Las Vegas on Paradise Rd (north), somewhere around E Desert Inn Rd intersection. Quite big plates.
It looks like the same problem which was discovered at 2013-2015 Lexus ES/Toyota Avalon:
https://www.autoblog.com/2015/11/04/...and-es-models/

It is also discussed here at this forum for Lexus ES:
https://www.clublexus.com/forums/es-...nd-es300h.html

I think that LS from the same years could use the same sensors/software and the same problem can also affect LS. I submitted a report to NHTSA and to Lexus.

 

Thanks, Clayton, for the very helpful info and for starting this thread. With APCS on my 2014 LS, I will be very wary now when encountering road constructions or other steel structures. Fortunately, for your daughter, the PCS activated at a fairly low speed, but it could have still triggered a chain-reaction accident due to the sudden braking. I can only imagine the risk of accidents if this happened at highway speed. So far, in the 20K miles since I bought the car, PCS has activated due to some aggressive passing maneuvers on my part, but not due to any obstacles or steel plates on the highway.

 

You are right. I also found it at the manual. But how this can help? When I see a steel plate, I simply cannot stop on the road, switch off PCS, cross over it, stop again, switch it back on... :-D

 

I remember reading somewhere by keep pressing the accelerator harder and turning the steering wheel (kind of over-ride mode), PCS would give control to driver. I will check that again post the link.

 

Yeah, satiger, it's good to know about the PCS override technique. I wonder though, how many of us will remember this when we suddenly experience an inappropriate PCS event? The PCS override maneuver is counter-intuitive.

 

Here is the 'override' option in the event of unwanted PCS activation; (also refer attachment for more details, nice read)

" Pre-Collision System3 with Pedestrian Detection6 automatic system cancellation may occur if there is a failure with Pre-Collision System with Pedestrian Detection, at which time the warning light turns ON or flashes and a warning message is displayed. The pre-collision braking function may not operate if certain operations are performed by the driver. If the accelerator pedal is being depressed strongly or the steering wheel is being turned, the system may determine that the driver is taking evasive action and possibly prevent the pre-collision braking function from operating. In some situations, while the pre-collision braking function is operating, operation of the function may be canceled if the accelerator pedal is depressed strongly or the steering wheel is turned and the system determines that the driver is taking evasive action"

 

Hi satiger, come to think of it, this is what happened to me when I was passing aggressively in a couple of instances. I am quoting myself from above.
When I was performing this aggressive maneuver, PCS activated but not PCS braking because I was stepping on the gas and turning the steering wheel to overtake traffic.