Abrupt Phantom Breaking at high speed - scary

[Jerryr]

My wife is recuperating form Spinal Neck surgery fusing C-5-7 a week ago. Today we went to the Dr for a Post-Op appt. On the way back our Tesla Model Y exhibited phantom braking with nothing in front of us, That caused her head to lunge forward and backwards. She is now in pain again. WTH!

I will not take her in the Tesla until her neck is fully healed. I will take out Ford Lightning until then. The Lightning NEVER phantom brakes.

Well it happened again yesterday.

We were traveling from my cabin to my house on a 2 lane undivided rural road. I needed to get the Tesla home because I have a service visit scheduled next week. Otherwise I would have driven our Lightning. The internal and external temp sensors are displaying crazy temps 124 internal and 164 deg outside. This caused efficiency to drop about 30% due to what I expect was the AC was trying to cool down what it thought was a 124 deg cabin. I was driving the speed limit to conserve energy so I could make it home.

So we were traveling at the 60 mph speed limit and a Semi trucker was tailgating me. Just like some scary movie where there is semi tractor trailer road rage.

Out of the blue our Tesla slammed on it's brakes and I immediately hit the accelerator. The Semi locked up his brakes and I saw tire smoke in the rear view. I'm sure that the truck driver thought i brake checked him. He then followed at a reasonable distance. I exited the road the first chance I got to let the Semi pass me. I felt bad that this happened.

My wife is still recovering from neck spine surgery and luckily she wasn't hurt this time.

 

[stopcrazypp]

Our car: 2019 Model 3. Our last 4 trips on the I-405 North from Orange County, CA to LA County, CA, a sudden unexplained slowing occurred at almost the exact same place and around the same time. We were using Cruise Control with Auto Steering. Here are the details from our notes:
5/12/24, 9:50am: driving N on I-405; abt 1 m before Westminster Blvd Exit #19; abt 200yds before seeing Westminster Blvd, 1 mile sign; abt 50yds before going under overpass; going 70mph on Cruise Control (and auto steering); clear lane ahead; suddenly slowed from 70 to abt 45mph; after 5-10", corrected to 50mph on Cruise Control.
5/19/24, 9:50am: driving N on I-405; abt 1 m before Westminster Blvd Exit #19; abt 200yds before seeing Westminster Blvd, 1 mile sign; abt 50yds before going under overpass; going 70mph on Cruise Control (and auto steering); clear lane ahead; suddenly slowed from 70 to 45mph; after abt 5" I accelerated back to 70mph, then restarted CC; it had self corrected to 45mph.
6/9/23, around 9:10am: driving N on I-405; abt 1/4 mile before Magnolia Exit; going 75mph on CC; sudden drop in speed to 65mph for no reason, I quickly returned CC speed to 75mph; then, very shortly, abt 1 m before Westminster Blvd Exit #19; abt 200yds before seeing Westminster Blvd, 1 mile sign; abt 50yds before going under overpass; going 75mph on Cruise Control (and auto steering); clear lane ahead; suddenly slowed from 75 to 45mph; after abt 5" I accelerated back to 75mph, then restarted CC; it had self corrected to 45mph (this was almost identical to events on 5/12 and 5/19.
6/22/24, 9:02am: Again! driving to Lisa's; N on I-405; abt 1 m before Westminster Blvd Exit #19; abt 200yds before seeing Westminster Blvd, 1 mile sign; abt 50yds before going under overpass; going 70mph on Cruise Control (and auto steering); clear lane ahead; suddenly slowed from 70 to 45mph over abt 4-5"; I resumed 70mph on cruise Control.
Weird!!!???
Tom and Lynn driving Obi Wan, Tesla Model 3

Slowing to 65mph at certain points is very common. It typically happens right after a curve. There are two spots in my regular drive where it does that and I know to just accelerator override it. I think it is probably just a mapping error for the curve slowdown function (Tesla has curves mapped where it slows down automatically as it approaches a curve). I'm guessing it's detecting the waypoint from the opposing traffic lanes as applying to the current lane.

As for slowdowns fo 45mph, it may be seeing some lights that look like traffic lights or some cue that makes it think it is on a local road. Could also have to do with passing the underpass, where GPS map doesn't know that the road above or below doesn't apply to it. In the US Tesla doesn't use advanced nav maps (unlike in China where they recently signed to use more advanced 3D nav maps).