Harsh braking and auto start/stop on highway

I had a really worrying experience driving on the highway. I was in Normal mode. I would like to know if any 3rd gen owners have experienced similiar. I was driving and the cars in front of me suddenly slammed on brakes. I was not following too close, but I hit the brakes and I felt the safety system kick in also, it got me to a complete or near complete stop, rather than just slowing down. I looked in my rear view and saw a car behind me trying to react to my braking, I immediately tried to hit the gas to give them more room, but there was a noticeable lag between when I hit my foot on the gas vs when the truck actually moved. My theory is auto start/stop was engaged on the sudden braking and that is why it took a second for the truck to go when I hit the gas. I left the auto start/stop off the rest of the time.

This could have resulted in an accident because of the safety feature that kicked in. My reaction times were way more appropriate then what the truck was doing.

any thoughts or similar experiences?

 

Yep this happened to me during the first 1k miles but hasn’t happened again since.

 

There's a TSB for this. Atleast this sounds like it would be the same issue. See post #10 in the ultimate service bulletin thread stickied on main 3rd gen page. Experienced this several times no matter what auto start stop was set to. It's been a couple months and several thousand miles since I've had it done with no more issues.

 

Not in the truck but had the auto brake execute once in the Camry commuter I had. It is very abrupt as in loose your lunch on the dashboard.

 

Are you sure you didn’t have cruise control on?

 

I did not have cruise control on when this happened

 

mine was in the first 800 or so. How has it performed in this somewhat rare situation since the 1000 miles?

 

My truck was built End of January 2023, would that TSB have been programmed during the build phase?

 

Ah, I wouldn't think so. But maybe worth asking your dealer.

 

mine was in the first 800 or so. How has it performed in this somewhat rare situation since the 1000 miles?

It’s been great. Haven’t had that issue again but it’s due for 5k miles service. Taking it in tomorrow and let them know of the issue.

 

If it's anything like the 4Runner, you might be describing the brake boost/assist. The brake pedal senses the velocity (acceleration) of the brake pedal, and acts on your behalf to stop, RFN. That feature allowed the stock 4Runner to come to a complete stop from 100 mph in a distance only ~20 feet greater than it took a lamborghini murcielago. Or maybe it was the aventador. Either way, interesting stuff.

 

no good if it isn’t “looking” at a car behind you that is trying to stop also. I wanted to accelerate from the stop quicker, but the lag was dangerous, it really pissed off the driver behind me.

 

I don't know what to tell you. First, I'm not sure if it was a malfunction, or the brake assist that I mentioned. If it was, now you know about that feature. Perhaps you could try to recreate that vehicle reaction, in a safer location to test it, and at what point it activates.

The vehicle isn't responsible for driving you and keeping you safe, you are. Even if the "system" hadn't kicked in, there's no telling whether the person driving behind you would have seen you braking, or braked in time. We'll never know. All you can do is avoid the accidents you're able to, and it seems in this case, you deemed the problem in front of you to be greater than the one behind you.

It would go a long way if people started maintaining proper following distances again. Seems like everyone is in a rush/tailgating, these days.

 

I had a very similar situation with the brakes taking over to avoid a collision. I was on them quickly but the collision avoidance system decided the brakes needed to be applied to the point of tires chirping on dry pavement. I came so close to hitting him that I counted six points and could see the OH S#%¥ on the buck’s face. The system works and my grill still looks brand new. I’m a believer.
There was a one second lag before the gas pedal responded when I pressed on the gas right after. I have heard some people hit the gas by mistake in emergency situations. Maybe gas pedal inputs are blocked when the system engages.

 

True, but I’d prefer to have a way to turn off at least some of these features. I trust my ability to avoid an accident more than the safety technologies ability to help me avoid an accident.

 

The sensitivity of the precollision system can be adjusted I think. You should check your setting if you think you were not going to crash and had enough space.

 

I have had a few instances where the PCS kicked in for no good reason. This happened most recently when starting to drive when a red light turned green. I had ample room in front of me. The car ahead of me drove off, and so did I, but PCS braked for me. I have this incident from the dash cam footage. The car behind me nearly rear-ended me, but did not thankfully.

PCS is a sticky setting that turns itself back on if you turn it off. So as a workaround, I decreased the sensitivity of the feature to 1. It was at 2 before.

 

nearly 20 posts and finally the solution is mentioned.

Just turn down the sensitivity on your pre collision system, solved

 

I agree with the above, but.... I have had new Toyotas since 1994, still have an '82 2wd truck. There is/has been a 'lag' in throttle application (?) On the auto trans.

I wonder if is the torque management of the trans 'logic'. It has happened to me in my 06, 14,

 

there is an option in techstream/carista where you can set it to remember last state (carista will throw up a major screen warning when you do this) instead of going back to default setting (on/off)

 

I had a similar experience in an Infinity G35 about 15 years ago. I was at an event called the BMW experience. You drive the cars around a circuit with a race care driver in the passenger seat. Starts with a series of S turns, then a hair pin turn, straight away and finally a 90 degree turn. BMW provided a 3 Series, Audi Quattro and an Infinity G 35. When I got to the hair pin in the G36 and swung the rear end around to line up for the straight away, the car just stopped. Engine was still running but gas peddle was disabled. Seemed like an eternity but probably lasted for 60 seconds. The other cars didn't do that.

 

Just bought my first Tundra, a 2023, 1 week ago, 380 miles on it and this exact situation happened to me today. At a red light left turn lane and light turns green, car in front of me was moving away faster than I was moving and already began turning left and the Tundra just slams on the breaks for no reason, my dog in back seat goes flying and the BMW behind me almost rear ends me.

I’ve always hated the driving “assistant” crap on cars and this just reinforces that opinion. Could have easily gotten rear ended in a week old truck because of a “safety” feature, stupid.

 

Ever since I lowered the PCS sensitivity to 1, this has not happened again.

 

OP I had a similar experience this past week.
I was traveling about 65 mph and came around a curve and traffic is breaking hard in front of me , I reacted and slowed to around 40, let up to pump my brakes so traffic behind me could see we were slowing suddenly. The engine died and re started when I got back on the accelerator. Weird feeling. I’m planning to disable this crap.