It seems that auto Start/Stop is getting confused when brake hold is used.

The engine stops at a light on auto Start/Stop (as it should) but it restarts right away when releasing the brake pedal (because brake hold will, well, hold it).

I think there is a program that needs to be fixed?

 

This is expected function as designed I would think. The brake hold system is released on application of the gas pedal, but there is a reason S&S starts the engine when you release the brake pedal, the designers want the engine started by the time you get your foot onto the gas pedal, not after you've already started pressing on it.

 

Not sure I follow Droid13, Start/Stop should keep the engine off until it’s time to go. In the case of Brake Hold, until the driver hits the gas pedal.

Otherwise, Start/Stop has little use (benefit) when using brake hold since drivers let go of the brake as soon as the brake hold function gets a hold of it. 🙂

 

I ran into this same issue, and I didn’t get it either. I found that when using the brake hold, press the brake firmly so you activate the auto stop system. Then, once the brake light comes on letting you know brake hold is engaged, wait several seconds before taking your foot off the brake pedal. For me this keeps the stop start engaged till you press the accelerator, which logically makes sense in my brain when using the brake hold.

 

Interesting work around, I’ll try that @LilyTiger. 🙂

 

Let me know if it works for you!

 

Well I did try it myself and you're right, that does work. I am a bit surprised still though that they would set it up like that in a non-hybrid to start the engine only after your foot is on the gas. I personally didn't like it because of the delay, step on the gas, wait for engine to start, then go. I'm sure some would call this a safety hazard if you are trying to pull off a quick left turn and not getting immediate response, but I suppose if the driver is aware of the delay and can plan accordingly its actually not bad.

I did learn that the hold system once turned on remains turned on. Interesting. I thought it was on only for the current stop, but it stays on for every stop. Pretty good if your foot is getting tired in traffic.

 

Glad it worked for you! I do understand where you’re coming from with grasping the practicality of it in certain instances. The way I see it, when using brake hold, people want the equivalent of the brake pedal being held without having to press the brake. So when people take their foot off the brake, they basically want the brake pedal to feel like it’s still being held. So if the stop start system is engaged, the only way for it to release is by pressing the gas since the brake is still pressed.

I personally find any delay to be very minor. The only time I’ve noticed anything quirky was when accelerating fast once I heard a clunking noise which I just attributed to the brake not letting go fast enough. But in certain situations I see how not having that delay could be beneficial. Maybe that’s why they make you hold the brake a bit longer to activate stop start, so you’re aware that there might be a delay.

and yes, brake hold is especially helpful in stop and go highway traffic! I’ve also just used cruise control. When it’s time to go again I can just press the button on my steering wheel.

 

I got an NX250 as a loaner from the dealer and the start/stop behaves properly on that model. i.e. engine does not start when taking off the foot off the brake. It only does when hitting the gas. 🙂

That makes me think that our NX350 could be fixed (reprogrammed) to work the same way. 💁‍♂️

 

I've actually started to use mine fairly frequently lately. For me, it works as you hoped. Come to a stop, press on the brakes long enough for engine to stop and hold light to come on, then release. No engine restart.

 

Interesting. Your vehicle must have a more recent version of the « system ». 👍

Mine restarts as soon as I release the brake. 😕 Which defeats the purpose…

 

Just a follow up note for you. Yesterday I started to see this happening more frequently. After a long 2 hour drive with very few stops, I came into town and noticed the engine would start 60% of the time releasing the brake with the brake hold system on. Reminded me of your comments. I experimented a bit with how fast I release the brake or how hard I pressed down on the brakes, but I really couldn't find a pattern before arriving at home. It did work sometimes but more than half the time not. This morning, everything back to normal, 100% of the time engine stayed stopped after releasing brakes with brake hold.

I am curious as to why myself now. Could be heat, but even though I was driving for a long time it was a very relaxed drive around 70 to 85kph on country roads, beautiful day, windows open/no AC, turbo snoozing mostly so I can't see that being cause for a lot of heat build up. I've seen worse heat on daily commutes on hotter days but typically my daily commute is < 30 min. I have no idea how the brake hold system works, but I'm thinking it doesn't utilize the electric parking brake as that makes a very specific noise. I'm thinking maybe it is vacuum operated, and this would be engine operated. Maybe conditions were such that there was insufficient vacuum to hold the brakes without the engine running? Interesting...

 

This is really weird @Droid13

Based on my experience with the loaner NX250 that worked flawlessly every time, I would lean towards “programming” issue in the system. But then, I’m no expert. 💁‍♂️

 

I have raised this issue with my Lexus dealer who felt that all NX350 were like that. 😕
I raised the issue with Lexus HQ (by mail) and they referred me to the dealer who should do the diagnostic and refer to HQ experts as necessary. 😕

Would any of you have any further info/progress on this?

 

I installed an automatic cancel for the start/stop system so I've put all that nuisance now behind me now. As with all new things, I tried to embrace it initially (back a year ago when this topic was last discussed) and it sort of worked ok most of the time but after a year or so of gradually turning it off manually more and more often to the point where I was always turning it off, I then installed the auto cancel. The entire issue of making the start/stop system stay stopped with brake hold became moot because even without brake hold it would function so inconsistently and when it did, 95% of the time the engine would restart within 2 or 3 seconds anyway while still stopped and foot firmly on the brake. Experiment concluded for me.