Help me try to isolate if what I am experiencing is only on my car, all hybrid RXs, or all gas RXs.

The HSA on my hybrid is very difficult to activate. I have to use more force than I think is necessary and reach the bottom of the brake pedal in order for it to begin. Sometimes, the brake pedal is depressed all the way and yet I still need to give it a bit of extra force. Also, lets say I am on a straight road and activate HSA. Obviously when I release the brake, the car does not move forward. However, waiting 2 seconds or so will auto deactivate it. When it deactivates, the car almost lurches forward like its a immediately release. It doesnt just slowly idle forward. The same is if I step on the gas while HSA is activated on a straight road. The car almost releases the brake hold too quickly and again the car lurches forward.

I got a gas powered RX as a loaner and noticed that the HSA could be easily activated and I didnt even need to reach the bottom of the brake pedal travel. Also if it released itself or if I stepped on the gas pedal on a straight road, the car seemed to start rolling very smoothly as if HSA was never activated in the first place.

Not sure if these differences is between the RXh and RX or just my car

 

Humm. I have a 2013 RX450h. My first vehicle with hill assist. I come up a hill about half the time to my home, and generally get stuck at a light where hill assist has proven to be a useful function. The truck will go backwards from my stopped position if I'm not quick enough to the gas or use Hill Assist. Yes, I have to push the brake down a little harder from where I am at the stop light, but I just push beyond and it clicks in "most" of the time. I have noticed a couple of times that it didn't seem to come on when I thought it should, but didn't give it a lot more thought since I needed to get moving with the light having turned green.

I thought I read (It may have been for the similar function on my new MBZ that I've been prereading manuals on, not my RX) that Hill assist specifically won't engage on flat or in downhill situations... Is that what you mean by "a straight road"? I do know I tried it a few weeks/months ago when another person here was trying to make it work and I was practicing to be able to describe it to him -- and now that I think about it, I don't believe I could consistently get Hill asssit to engage when my RX was on flat surfaces. I've not had a problem on a real uphill stop situation that I think Lexus Hill Assist is really designed for. I'll try it again tomorrow when I'm out and report back if something is different from the way I've described it here.

Additionaly, I've not had the lurching problem you describe.

 

I've only engaged hill assist a few times, once on a hill and a few times on a flat road to test it out. I pressed on the brake firmly but the pedal didn't go down that far. And it eased forward quite smoothly. This is your second brake related issue. I'd say it's time to bring your RX to the dealer and get it checked out. Good luck.

 

Like Bert say's, it does require extra effort to light up the HSA light. Normal use is to keep your foot on the brake when on a hill but it will prevent the normal roll back (long enough to get to the gas, probably a couple of seconds) when you remove your foot on a hill. A couple of weeks ago you were posting about your brakes so maybe it's time to go to the dealer and have them checked. Then come back on and tell us what you learned if you can.

 

When I was at the dealership after buying my 2013, the guys couldn't decide if my car had HSA or even how to activate it. Seems temperamental from what you guys detail above.

 

I wish HSA also included a brake hold feature when at stoplights

 

As much as I love my Lexus and am a huge supporter of their reliability, they are probably too conservative and don't go as far in automation/technology as some mfgrs. Look at the Mercedes-Benz implementation of what we call in Lexus land as Hill Assist... it's HOLD capability will do what I think you're asking for, e.g. when you are stopped in traffic, you can take your foot completely off the brake for an extended period until you step on the gas (that seems frightening to me, but could be done). Similarly, several of the MBZ technologies will literally attempt to fully stop the car in an emergency, vs Lexus that only slows you down when traveling over a certain MPH, and uses an audible notification with an expectation the driver will actually bring the vehicle to a physical stop.

 

thats true bert, but Lexus has all of these technologies but only reserves them for higher end vehicles. MB on the other hand has the same tech across the line. The presafe distronic plus systems found in the C class are the same as those found on the S class which is great.

The LS and GS both have brake hold functions at stop lights while the LS has full safety braking as well

and in reference to your post above, I am talking about flat land

 

Completely understood and I agree.

My point was trying to be that other brands do implement the technologies differently. It was my decision, but will be a bit challenging for me to own both the latest MY technology RX as well as the latest MBZ SLK, with the later being far superior in how they allow technology to assist (or intervene if necessary) the driver in emergency or preventive-accident situations. If an emergency occurs, I suspect and hope I'll execute upon the least common demoninator.

I am not quite a Lexus fan-boy, perhaps close to it given my mostly positive experience over nearly 20 years, but Lexus could do a lot better implementing such technologies just a little bit earlier, and making them available more consistently across their models. It would be even more so for me to have say, "hill assist" on my RX that operated one way, and if I owned a different model Lexus in a roughy equivalent MY, if it too would probably have similar capabilities. Lexus' packaging and delay or marketing decision to not make something available in certain models is what for me is most challenging, and I believe will ultimately cause Lexus to loose some amount of share if they don't step up to the plate just a little bit more. I can hopefully keep it straight what functions I have when I'm in my Lexus and new MBZ when it arrives next month, but if I owned two Lexi again -- as I would have preferred to -- it would be so much simpler and create less room for driver-error if Lexus changed their philosophic implementation. You hit on a key difference in at least these two brands. I believe consistency in implementation within the same brand and a MY or two would be a superior implementation than where Lexus seems to be continuing.

 

You and I are on the same page. I love how MB so quickly updates their products so that all models share similar technologies and styling. It is taking Lexus forever to get LED DRLs on all their models when all Audi and MB models have them. Not sure why it is taking so long for the GX to get them. Just a small example but proves our point.

 

I agree my Audi A6 has some minor things like the above mentioned that aren't present in the RX350 that is 5 years newer then my traded in 05 Audi.
1. Brake Hold -<though once it wouldn't release so I was too scared to use it after Audi fixed.
2. The other big thing is the locks on my Audi and our Merc (both traded) would remember that you had pressed the drivers door unlock, so when you pushed it again no matter the delay; all doors would unlock.
3. The radio stays on with the ignition off till the door is open. And no matter the delay from engine off; All door would unlock when drivers door was open. With my RX you have to open within seconds.
4. Finally one last thing the Audi Keyless system would work on all doors not just the driver and passenger front door.

though most importantly LEXUS IS RELAIBLE haven't been to service since buying expect oil change and tires, etc.

 

^^ those are some great ones. Also lets say you turn off the engine while the wipers are going, most european cars also have it where they will continue the full wipe and back to the off position, or if it stops midway, turning the key will immediately change the direction of the wipe so that it goes back down

 

It's on old thread but I hope this is usefull for future readers. I have a 2010 RX450H bought recently. I could not get HSA to activate. Today I finally learned how. You need to step on the break with 1 fluent motion all the way down, not giving to much force. If you break slowly and then break harder, for me, HSA will not activate. So break in 1 fluent motion down and it works.