Sven

Braking in the regenerative zone - no brake lights coming on

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Hi all,

it's been a while since I was on this site, I went from my trusty solid IS200 to an Audi A6 4.2 (don't judge me!!) and learned that mistake (£7,000 in the last year!!), so I went and bought myself a 2013 IS300h F-Sport.  What a car.... I have to say that it's the nicest car I've driven, but I do have a major concern which I've raised with Lexus, just wondering if anyone else has noticed it.

Driving along, and this can be at any speed, if you press the brake pedal to slow the car down, but only do it in the re-gen area to recover as much energy as possible, the rear brake lights do not come on.  There is sufficient deceleration of the car to bring it to a complete halt without ever having the lights come on and it's not just a "coasting to slow down" speed, it's enough for you to feel the car slow down (engine braking if you like). If you're stuck in traffic, crawling along in rush hour, you can actually start and stop moving just by using the brake pedal without it ever coming on. 

You only illuminate the lights if you press the pedal harder.  It's just a bit more pressure, but when trying to get the most economy out of it, I/you try and re-gen as much as possible.  

I only noticed it in the winter and using reflection of the 3rd brake light on the parcel shelf in the window (try it yourself when it's dark).  I approached my local Lexus dealership and they confirmed that all of the modern hybrids do this.  I contacted lexus directly to voice my concerns and they booked me into the dealership to check if there was a specific fault with my car.  As predicted, no fault was found.  The engineers suggested that they could move the brake pedal mechanism, but that may mean that the brakes are on constantly... which would be bad.

My issue is software related - not mechanical.  The car knows that the pedal is pressed and therefor the lights should be coming on.. i.e it is my intention to slow the car down, please tell the cars behind me. Even F1 cars had to start providing a flashing light at the back to say that they were in a regenerative phase and slowing down faster than what would be normal.

I've had quite a few near misses, and the look of terror of the person behind me being caught out by a car that's slowing down quicker than they'd expect (as there's no lights on) is now making me learn to slow down in a different manner - trying to gauge their distance and if I have to jump on the brake a bit harder and slow down even quicker.

I wonder how many rear collisions have been caused by this.  

I'll keep you up to date with any further feedback from Lexus, but it would be interesting to hear your thoughts and experiences. 

 

Thanks all,
Sven.

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Brake lights on my 2016 RC300h come on at the slightest touch of the brake pedal. I have a long downhill to my house and use it to recharge the batteries by regen braking, I can see the brake light reflected in the hedgerow and road signage.

 

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29 minutes ago, NemesisUK said:

Brake lights on my 2016 RC300h come on at the slightest touch of the brake pedal. I have a long downhill to my house and use it to recharge the batteries by regen braking, I can see the brake light reflected in the hedgerow and road signage.

 

I live at the top of a hill in north Yorkshire and do the same thing, and my lights don't come on.. they do if I press harder of course.. ;-) 

 

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In some proportion, it seems to me correct, as braking is different from simple decelerating,  in traditional cars if I change gear o decelerate without braking lights keep off. nonetheless, in automatic cars when I want to slow down I must touch brake pedal and so lights go on.

Rather than a sw issue my be it's only a mechanical one, may be i's just necessary to verify the correct position of brake light switch situated over the brake pedal that activates too late because of wrong position.

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this sounds strange to me... th lights in my IS300h from 2015 do come on the moment i touch the pedal which sounds logic to me..

maybe an idea to ask the dealer if you can have a spin in another IS they have so you can see if its throughout the range or your car specific which i think it is?

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You only have to breathe hard on the brake pedal in my 2005 RX300 and the lights come on, which is how most of the other cars I've ever had worked as well, so I'd say something definitely wrong. In all my other cars it's simply been a little microswitch above the pedal that makes contact as soon as the pedal moves but I'll bet there's some complicated ECU controlling the brake lights in a Lexus :whistling:

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53 minutes ago, sorcerer said:

You only have to breathe hard on the brake pedal in my 2005 RX300 and the lights come on, which is how most of the other cars I've ever had worked as well, so I'd say something definitely wrong. In all my other cars it's simply been a little microswitch above the pedal that makes contact as soon as the pedal moves but I'll bet there's some complicated ECU controlling the brake lights in a Lexus :whistling:

We are talking hybrids here, which may well operate differently from 'normal' models?

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3 hours ago, NemesisUK said:

Perhaps this is a model/year thing?

My 2013 IS brake light comes on with the slightest of touches, certainly before the mechanical brakes apply.

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Yep mine also comes on at the slightest touch. It's a 63 plate.

I wouldn't expect later models to be any different.

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I 2nd it that you get your dealer to double check the brake light switch is adjusted correctly. I'e had that same problem with a coupleof cars over the years.

It's not a hybrid thing.

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I concur.. most brake switches are adjustable and there are pedal travel tolerances for them to activate the brake lights in workshop manuals. Adjust them to suit I guess if you know what you doing..

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Using regen braking mode, my GS300h can be softly braked to a halt and held stationary without the brake lights coming on. I like being able to hold the car stationary without blinding the driver behind me but I do wonder if this brake behaviour is correct and legal.

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Just reversed mine into the garage and slight pressure on the brake pedal lit the reversing lamp

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On the same theme does anyone know if the brake lights come on when the car slows in Radar Cruise Mode.    

I assume they do but have never been able to check

Tel

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On my CT the lights come on as soon as you touch the pedal

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Hi, my IS300h (17reg) flashes brake signals with slightest touch of the pedal, beside of that when I`m in cruise control on motorway if car radar thinks he need to brake and does that automatically brake signal goes on as well. 

 

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It is the same on my 3RX. Slight pressure on the brake pedal will slow the car down without the lights coming on. In fact, I can keep my foot on the brake pedal to prevent creeping at red lights without blinding the person behind me. Might be better for them, but I wish the light was more sensitive.

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On my IS300h the lights don't come on if i lightly press the pedal and it's only using regen braking. Not sure at lower speeds when that engages the actual brakes, i'll have to check.

 

In my view the regen braking is so slow that there is no need to put on the brake lights, it's equivalent of using engine braking. A driver who wouldn't notice you slowing down would either have to be very distracted or very bad and both should have no place on the road.

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3 hours ago, TBi said:

In my view the regen braking is so slow that there is no need to put on the brake lights, it's equivalent of using engine braking. A driver who wouldn't notice you slowing down would either have to be very distracted or very bad and both should have no place on the road.

Must admit to finding the regen braking to be quite aggressive in my RC, certainly knocks off the speed quickly!

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My brake light comes on with the lightest of touches even before any actual braking takes place. I find it really useful when someone is tailgating me. A slight touch with my left foot sure puts the willies up them with no risk of a rear ending!

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23 hours ago, NemesisUK said:

Must admit to finding the regen braking to be quite aggressive in my RC, certainly knocks off the speed quickly!

If you find it aggressive then you are probably using the regular brakes as well. The car can brake while doing regen, it isn't 1 or the other. 

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So Sven. What's the latest?

I forget to mention when I last posted that my brake light comes on with the slightest pressure on the pedal. 

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