Gas & brake together warning/hill assist

Or in the case of the AT, it keeps the brakes engaged until you tap the gas pedal.

Which to be perfectly honest, I don't notice much. I'm a believer that one should be firmly planted on the brake when waiting at an intersection, at all times. When it's time to go, transition to the gas before you even have a chance to roll back.

I've done that on hills, in the wet, snow, and with a full payload. As I mentioned the first time, that's a fundamental skill that every holder of a driver's license should possess. MT or AT, two wheels or four, assisted vehicle or no. Rolling back and/or loss of traction is 100% driver error.

 

I will admit to using the parking brake method with my 6mt on really steep stuff off the road. I find it more reliable and also allows me to focus my brain on other hazards.

I'm still confused about how hill start assist works. Does it prevent the truck from rolling back completely or does it let it roll back slightly? Does it use the ABS brake system or something else? I assume the noise people are referring to is the ABS brake system, but no one has actually confirmed that. Is it possible it was activating on my 2016 SR5 auto and I didn't notice it?

 

I still think it's different on different trims. People describe very different experiences than mine.

On the Sport (with the vacuum brake booster, not the electronic booster that's on OR and Pro trims) the hill start assist works like this:

When you release your foot from the brake pedal the truck will continue to hold the brakes until it senses one of the four following conditions:

• The gas pedal is pressed
• the truck rolls forward (no hill or downhill condition)
• A certain amount of time has passed (2 seconds according to the manual, I have gotten a longer hold when I tried it out of curiosity)
• The shift lever changes position

That's it. So in other words, the truck "two-foots-it" until it senses you're on the accelerator, then it releases the brake. I assume there's something a little more complex in the software considering it will allow rolling forward but not backward. I'm not sure what system controls it either.

I do know that I have defeated it once or twice when absentmindedly parking in my driveway. I'd stop (waiting for garage to open) then just barely shift my foot to the gas. As soon as it senses movement in the gas pedal, it lets go. I've rolled backwards doing that. But I also didn't think much of it either, because a quick blip of gas immediately got it rolling in the right direction.

 

That makes sense. I know the OR/Pro have a different brake booster, but I don't understand why the behavior would need to be any different. There is possibly some subtle engineering detail I am not privy to.

I also don't understand why the OR and Pro 6mt don't have hill start assist, because it seems like the 2 trims that have the greatest need for it. I've been in some sketchy situations where rolling backwards was not going to be a happy ending. I definitely think autos have some advantages off the road. I still love my manual though.

So I think I'm both with and not with the OP. It would be nice if the brake start assist on the OR/Pro worked as well as on the other trims and I also think that anyone driving an OR should have skills enough to preform a hill start with confidence. Practice makes perfect.

 

Exact same with my Sport auto.

However, I also went one step further. After I took my foot off the brake on a very steep hill, the hill start assist held the truck for 2-3 seconds. But I wondered what would happen if I didn’t do anything.

After hill start let go the truck immediately rolled back and the engine died. No power assist on the brakes or steering. Took quite a bit more effort to get the truck back under control. Got the truck stopped, placed it into park and was able to start it again and back into drive and away I went.

 

On a TRDOR, even a slight incline will make the truck roll backwards, it's almost like being in neutral. I'm guessing Toyota puts less than required drag on the engine to increase mileage.

 

I’m not seeing any connection between hill start assist and fuel economy.

 

Didn't say there was. I said Toyota doesn't put enough converter drag on the engine when stopped to keep the truck from rolling backwards even on a slight incline. One reason might be to get slightly better mileage.

 

Still not seeing any connection or not understanding what you are saying.

 

The engine drives the truck forward through the converter. When stopped, the converter slips to a certain extent or the engine would die. On the TRDOR it slips too much, letting the truck roll backwards on even a slight incline. If the converter slipped less it could hold the truck in place but the ECU would have to apply more throttle to keep the engine from dying.