Rando-braking

[leedr74]

I was cruising down I-35 from Austin to San Antonio and had TACC and AP running when all of the sudden the car just went to a halt!

I luckily had it the pedal so the car behind me didn’t rear end me going 70!

All in all things played out ok but geez did it truly scare me and the rest of the ride had me driving with anxiety.

TIA, I’m running the latest update “7” in my M3 LR AWD.

 

[tvad]

Unexpected random braking and resulting anxiety is precisely why we don’t use TACC or AP.

 

[leedr74]

Unexpected random braking and resulting anxiety is precisely why we don’t use TACC or AP.

Ok so it wasn’t my imagination then. Phew, relief for now...

 

[iwannam3]

Seems to happen to me near shade from an overpass.

 

[JulienW]

Just do a search for Phantom Braking. Also your car didn't "...just went to a halt!".

 

[lolder]

I was cruising down I-35 from Austin to San Antonio and had TACC and AP running when all of the sudden the car just went to a halt!

I luckily had it the pedal so the car behind me didn’t rear end me going 70!

All in all things played out ok but geez did it truly scare me and the rest of the ride had me driving with anxiety.

TIA, I’m running the latest update “7” in my M3 LR AWD.

So it came to a halt which is a complete stop or did it briefly apply brakes and then resume? There's a big difference.

 

[ewoodrick]

So it came to a halt which is a complete stop or did it briefly apply brakes and then resume? There's a big difference.

Huge difference!

 

[JWSM3Owner]

Just did a long road trip through Appalachia, about 95% of which was driven on AP/TACC. The car randomly/sharply braked for no reason in two situations: coming uphill towards an overpass (presumably the car mistook the stationary overpass for a stopped car) and when approaching an exit with construction/barriers where the road was also curving, so that again the car probably thought there was a stationary obstacle in the road. The car pretty much immediately started accelerating again, though; it was a disconcerting jolt, but the car never halted.

 

[dethman]

yeah. one of those rando things that happens kinda frequently unfortunately.

 

[Not Sure]

Is that an underpass or a red fire-truck?
I'm just not sure.

 

[diezel_dave]

This will probably happen to anyone who uses TACC/AP regularly. My theory is that many of these events that I have experienced are caused by inaccurate lane tagging of adjacent slower moving traffic. That is to say, my car misjudges cars in the next lane as being in my lane and thus slows down to match their speed. This happens most frequently when driving around a curve where it really struggles to determine which lanes the other cars are in.

 

[afadeev]

I was cruising down I-35 from Austin to San Antonio and had TACC and AP running when all of the sudden the car just went to a halt!

I luckily had it the pedal so the car behind me didn’t rear end me going 70!

All in all things played out ok but geez did it truly scare me and the rest of the ride had me driving with anxiety.

TIA, I’m running the latest update “7” in my M3 LR AWD.

Yeah, it happens.
One of many TACC / AP bugs.

Eventually, you will learn when to expect them, and be prepared to over-ride erroneous AP behavior.

All part and parcel of Tesla ownership.

 

[emmz0r]

Watch the speed limit closely as well. I have had some major braking when the GPS speed data is inaccurate or when it is inaccurate position itself and gets the speed from neighboring off ramps etc

 

[Gaelic123]

I was cruising down I-35 from Austin to San Antonio and had TACC and AP running when all of the sudden the car just went to a halt!

I luckily had it the pedal so the car behind me didn’t rear end me going 70!

All in all things played out ok but geez did it truly scare me and the rest of the ride had me driving with anxiety.

TIA, I’m running the latest update “7” in my M3 LR AWD.

It has never happened to me.

 

[diezel_dave]

It has never happened to me.

You are one of the lucky few then. Make sure you never get complacent with the system because this can and will happen to you at some point in the future. It is just a matter of when.

 

[huangm777]

It’s funny but phantom braking has rarely occurred for me. Then again I’ve only driven the car 1000 miles so I probably haven’t hit the conditions yet...

What is interesting though is that the one time it did, it was on the exact stretch of highway that my Toyota Prius Prime would incorrectly activate the imminent crash warning. It was a curve on the HOV lane. Perhaps the tech is very similar after all...

 

[Ribeye67]

I have it happen on Highway 24 in number 4 lane when driving west from the Caldecott Tunnel near the Broadway offramp. speed limit suddenly shows 50 mph on the dash. I then accelerate until speed limit shows 65 again. Started turning AP off since getting off at next exit. AP is still great to have. It just needs work.