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Highlander Hybrid Brake Problems

PF_FlyerPF_Flyer Pennsylvania Furnace, PAPosts: 5,965
Having an issue with the brakes on your Highlander Hybrid? This is the place to work out a solution!

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  • poodlgalpoodlgal Posts: 13
    I am noticing a little "gap" in the brakes when I am slowing down and just as the ICE kicks off. It is as if the brakes let up for just a second (the car surges slightly as if I had taken my foot off the brake) - and then the brakes kick in again. It's a bit disconcerting! Has anyone else noticed this? I'll be checking with the dealer at my next visit, but wanted feedback from the group as to whether this is "normal" or an acknowledged problem. I don't remember this happening when I first got the car; I've had it 6 months now. Thanks for your advice/opinions!
  • cdptrapcdptrap Posts: 485
    We are experiencing this as well but randomly, not consistent and not often. Do you experience it consistent enough to notice a pattern? If you do, can you please share?

    Will be checking with dealer's shop as well in a week.

    Ours seems to occur when applying the brakes after coasting. As we step on the brake for the final stop, there is a slight surge (gap) and then the brakes take hold. It does not happen all the time.

    I wonder if it has anything to do with the car switching from "recharge-induced slowing" to actual braking.
  • nomorebenznomorebenz Posts: 109
    You're onto something there. I have noticed it on mine. May have something to do with the ISC (Idle Speed Controller). When you are close to stopping, the power flow switches direction and goes back to the wheels (to simulate ICE idle). This could be contributing the surge. Let's see what others have to say.
  • mmreidmmreid Posts: 88
    I've noticed this "surge" only a few times when I've been coasting towards a light or stop sign and the car seems to hit a slight bump in the road - but only when it hits a bump or other obstacle like a tiny pothole. I wondered what it was - felt like the car wasn't braking for maybe half a second and almost like it jumps slightly and then the brakes work just fine. I wondered if it was me or what. . .should we talk to Toyota about this? Is it a safety issue?

    mmreid :confuse:
  • katzjamrkatzjamr Posts: 146
    the 'surge' is normal as the regenerative braking adjusts depending on the amount of charge needed for the battery.
  • poodlgalpoodlgal Posts: 13
    This may be "normal" but it is disconcerting at the least, and seems like it could be dangerous. Yes, it occurs most often after I have been coasting (like stopping as I am coming to the bottom of a hill). Sometimes the surge or "brake gap" puts me a little further forward than I want to be - and in the case where I might be stopping in an emergency, might put me in the intersection or on someone else's bumper. If anyone learns more from their dealer/mechanic about a possible fix, please post it!
  • newski3newski3 Posts: 42
    I just returned from an 88 mile round trip to a small town up the road using paved 2 lane roads with little traffic. Two things:

    First, as I was returning home, I was descending a l-o-n-g downhill grade ;;; ah, regeneration time ( I was traveling about 50mph). At the bottom of this downhill grade was a stop sign. So, I began breaking at a reasonable distance out. Then, about 20 yards out I hit a short (about 2 feet) rough spot in the road. The brakes released for less than a second and reapplied with out my doing anything. The added stopping distance couldn't have been much. But wonder what would have happened if the rough area would have been, say 10 or 20 feet long?? By the way, the anti-lock brake system did not come on.

    Second, I was averaging about 27.3 mpg for about the first 200 miles of driving. Then, before today's short 88 mile trip, I was down to about 26.7 mpg and 300 miles. About 50 of these miles were highway and the rest around town (Stop and go but seveal blocks in between the stops). After todays highway trip at 50-55 mph, I'm again up to 27.4. Unlike the EPA estimates, I'm getting better highway mileage than city. I'm thinking that with a long city type stop and go period, more of the ice gas is used for recharging the battery than is the case during highway driving. In a week or so I am planning a 600 mile trip one way utilizing interstate highways all the way. I'll see what it does at 60-70ish.
  • katzjamrkatzjamr Posts: 146
    in a true emergency your car is equipped with sensors that know you are pushing harder than normal on the brake and will boost the braking power higher than usual, the surge or brake gap will not happen in an emergency, in fact vehicle will stop more quickly.
  • discussion1discussion1 Posts: 103
    I believe your observation is valid.

    I also noticed this sensation of "brake slip" when braking gently after coasting. The slip is so slight and fast, it leaves little time to react. The brakes kick in right after but it is disconcerting the first couple of times.

    When braking more decisively, the slip never happens and the car stops quickly.

    I wonder if when we brake gently enough, the system is still using regenerative braking and not the mechanical brakes. If so, it seems reasonable that when a tire loses traction for a second, the VDIM shifts power to other tires causing the surge sensation because of power transfer.

    It is possible we normally will not feel this function while coasting or with foot on the gas pedal. It becomes detectable when we are on the brakes because the VDIM operates the braking system.

    Just a guess. Someone asked earlier if this is a "problem". I think it is worth a call to Toyota for clarification. If nothing else, the call may cause them to research and look into it. If we all call, they will take it more seriously.
  • wwestwwest Posts: 10,706
    "..brakes released...." "reapplied"

    ABS....

    In the instance you describe your "braking" may have been TOTALLY due to regeneration...

    If so, and the front wheel(s) began to slip (no ground contact momentarily..?), even ever so slightly, in that rough spot (gravel, sand..??) the regeneration would instantly cease operation (release the "brakes") to simulate what would otherwise be a true Anti-lock Braking System, ABS, "function".

    I quite sure, certain sure, Toyota and Lexus wishes they could perform that very same functionality, absent a quick shift into neutral, with engine compression braking. That would improve the overall safety factor of FWD or front biased AWD vehicles substantially.
  • newski3newski3 Posts: 42
    I discounted the cause to be ABS because I did not feel or hear the rapid movement of the brake pedal, which has occurred on all of my other cars when ABS kicks in. Maybe the HH's ABS does not work that way.

    An added note: I do not recall seeing (although I must admit I wasn't looking for) the "slip" warning light as the HH manual describes.

    The rough spot was just that, rough. I did not even see it with my eyes. No sand or other debris was present. There was a slight drizzle so maybe a tire slip occurred??
  • doug28doug28 Posts: 30
    Great information on the mpg.

    I am having very similar results as yours.

    We live in foothill type community and so are usually going up or down a grade of some type.

    Living semi-rural we are getting about 27 mpg but go strictly highway, up & down some serious grades, using cruise and assiting it on the climb till near top, & we are getting 29.4 mpg.

    After highway driving & switching to city we've seen 29.6 mpg. Once we start the semi-rural driving again it drops to 27 mpg or so.

    This is all by the dashboard. We've mannually calculated the mileage and found it to be about 1 mpg lower than the dash but we are comparing dashboard to dashboard with our older family vehcile which averaged about 17.1 mpg in these same driving conditions.

    I too noticed the vechile "surge" while braking. I could be mistaken but found decelerating a little sooner than usual seems to help.
  • cdptrapcdptrap Posts: 485
    Your point about "...front biased AWD vehicle..." makes sense.
    Another question to ask is if the traction system is really active at speed below 25? The manual says all the electronic safety system activates above 25-MPH. So, does this slip thing happen above 25? or under 25? or both? Has anyone noticed the speed when it happens? I will pay attention next time.
  • tmsusatmsusa Posts: 81
    Re the braking sensation you and others here have described, poodlgal, the feeling that you are getting is characteristic of the hybrid braking system on the Highlander Hybrid.

    Not being one of our highly skilled technicians, let me explain simply that the braking system on the vehicle is designed to shift from the Regenerative mode to a pure Hydraulic mode as the Highlander slows to around 8-9 MPH. If you are not accustomed to driving one of our hybrids (same on the Prius, too, BTW), the sensation could initially be a bit disconcerting--But it is perfectly normal.

    When tmsusa first drove the current generation Prius, he too detected a slightly different feeling from traditional braking--also an amazing ability to "coast" seemingly endlessly without the usual slight engine braking feel on traditional vehicles. Great regenerative forward momentum, and made me more attentive to the sea of cars on the 405 here in SoCal!

    Thanks for being a Toyota customer--And as always, if you have any other questions or concerns about your Highlander Hybrid, your Toyota dealer should be able to help. Or give us a call and talk to one of our Customer Experience Center reps at 800-331-4331.
    .
  • cdptrapcdptrap Posts: 485
    TMSUSA, thanks for the informative post. Do you read our board here frequently? It will be great if you can, it is nice to have a Toyota Motor expert in this forum.
  • tmsusatmsusa Posts: 81
    Trying to keep up with it. We're finally recognizing that consumer-generated media--which would include this board--is rich with content that is important to us, particularly as it relates to our customers, products and brand image.

    But it's a bit of a one-man operation now, so certainly can't be everywhere all the time. Now, better get back on-topic before our host boots tmsusa! Thanks for your comments cdptrap.
  • landdriverlanddriver Posts: 607
    I own a non-hybrid HL and noticed it during the one time I test drove a HH -- probably because I'm accustomed to how a HL handles and thus was sensitive to any differences.
  • larry70larry70 Posts: 3
    My 2006 HiHi does not brake properly over ripples or small bumps in the road. It sort of hesitates its braking power.
    Has anyone had this issue checked by the dealer?
    Larry
  • cdptrapcdptrap Posts: 485
    I would ask the dealer just to be safe. But....... ;-)

    Are you refering to situations where you step on the brakes, the car begins to stop and suddenly there is a brief hesitation (1 sec), the cars feels like it is not braking and then quickly it brakes again and stops normally?

    This does not happen all the time, does it? Just occassionally, true?
  • larsblarsb Posts: 8,204
    Is this your first vehicle with ABS?

    I have had several cars and trucks with ABS, and they all have done that when braking hard on ripples or washboard roads.

    It is because the computer gets slightly confused when the tire loses contact with the ground, and the tire loses contact with the road then regains contact with the road over and over and over multiple times in very rapid succession during braking over that type of surface because of the bouncing that the surface causes.

    My recommendation is to plan ahead and slow down more before those surfaces and the ABS will not bother you as much.

    That always seemed to help in my cars.
  • wwestwwest Posts: 10,706
    Yes, since you are relying on "engine compression (regenerative) braking", at least partially, if the anti-lock system should activate, which it is very prone to do in the circumstance you describe, the regenerative braking aspect must be INSTANTLY disabled rather than have it inadvertently interfere with the functionality of the anti-lock system.

    Ford was awarded a US patent that addresses this very thing with regard to regenerative braking on the front wheels of a hybrid vehicle. The patent specifies reducing the regenerative braking level substantially while the OAT is at, below, or near freezing, and disabling it altogether in any or all conditions the INSTANT ABS activates.

    If you browse around on the various FWD and front torque biased AWD vehicle forums on the internet you will find that the industry is striving mightly to solve this very same problem with ALL FWD (and..) vehicles, eliminating the braking effects of the engine on these vehicles so as to reduce the rate of loss of directional control accidents due to loss of stearing capability and from unsafe interference with the functionality of ABS should the roadbed be slippery.
  • I would like to report a problem with the 2006 Highlander Hybrid braking system that also affects the Prius and the Lexus RX.

    When travelling at speeds under 25 mph, the ABS braking systems do not engage in an emergency stop situation. This has been reported on several forums, including http://www.hybridcars.com/forums/brake-failure-2007-t1013.html, and happened to both me (in a 2006 Highlander Hybrid) as well as my neighbor in her Lexus RX.

    In my case, I was travelling around 20 mph on the freeway. The person in front of me unexpectedly came to a complete stop; although I had plenty of space and quickly engaged my brakes, they never "grabbed"--I just slowed and coasted into the car ahead of me. Despite never having been in an accident in my 20+ years of driving, I am now liable for this rear-ender. I hate to think what would happen if a small child ran in front of me on a residential street where speeds are typically under 25 mph.
  • wwestwwest Posts: 10,706
    I think I have read somewhere that the Toyota HSD systems do not (can NOT..!!)use engine vacuum for brake power boost/assist, but use the ABS pumpmotor and brake fluid pressure accumulator system instead. If that is the case it may very well be that an EXTRAORDINARY level of pressure on the brake pedal is required to actually LOCK the front brakes and thereby force the ABS into activation.
  • That is interesting about the way the brakes may work on the hybrids. I was also in a situation prior to this accident where I was travelling around 35 mph and had to slam on the brakes for an emergency stop, and was actually amazed that I did stop in such a short distance. There is most definitely a difference between the way the hybrid brakes act in an emergency situation under 25 mph versus over 25 mph!
  • cdptrapcdptrap Posts: 485
    Hmmm... I do not doubt there are "bad apples" that have brake problems but are you suggesting this is pervasive? I like the info but why the emotive highlights?

    What is the definition and precise specification of "extraordinary"? 200-lb of pressure?

    My wife is a smallish 5-4 and a meager 128-lbs and she has been able to successfully stop this car at low speed (<=25-MPH) without complaints countless times. The only complaint we have is that sensation of "slippage" when the regenerative braking changes to mechanical braking.
  • cdptrapcdptrap Posts: 485
    Sorry to hear of your accident.

    At times, when we travel at low speed and with plenty of room in front, we automatically "meter" how we press on the brakes in order to achieve a smooth stop. Were you doing this and the brakes just did not bite as you would expect? Or did you slam on the brakes and they just did not work?

    We have had to make emergency stops many times at speed lower than 25-mph and the car have always stopped. This is true even when rolling downhill on our driveway at <10 MPH.

    I am not disputing your report, just trying to understand if this is an isolated incident or a potentially bigger problem.

    Thanks!
  • I slammed on my hybrid's brakes, and they did not catch. The exact same thing happened to my neighbor in her Lexus hybrid. I think it may happen when you have been travelling for a while at a slow, steady speed, then make an emergency stop. It's almost as if the brakes have decided that they are in the mode of regenerating and can't make the switch so suddenly to come to a complete, rapid stop. The feeling is one of coasting, as if on ice, at a slow speed. Others have posted of the same feeling on hybrid car and Prius forums--it seems to cross all types of hybrid cars.
  • This forum is the closest that I have found for what we are experiencing on our 2007 HHL. It is an intermittent issue that the Toyota dealership has been unable to provide satisfaction on. The issue first became noticeable to us last winter after about 15000 miles on the car. We now have over 30000 miles on the vehicle. This is our third vehicle with ABS, so we are familiar with how that system feels when it operates.

    First the issue: We intermittently experience the "braking gap" both above and below the 25 mph mark. It is more apt to happen when the car is cold. We live on top of a hill in the rural / suburban northwest corner of CT. Sometimes when we apply the brakes at 30-40 mph for the first stop sign, half way down the hill, the KW needle goes negative indicating regenerative braking, then the regen braking gives up and the needle goes to zero. To stop the car at this juncture, additional brake force is required to engage the hydraulic brakes. Initially we thought it was a cold car / cold weather issue. We have experienced the the "brake gap" in both hot weather and with the vehicle fully warmed up.

    After the last service visit, specifically for this issue, we were told by the hybrid tech that if the high voltage batteries were fully charged that the the regen braking would not engage. We now monitor the battery charge icon. The tech also mentioned that this battery charge icon is not very accurate. The highest level of charge we have seen indicated is a level above the + - signs at the top of the icon. The brake gap usually occurs when the batteries are at least 70% full to full.

    He of course explained how the regen braking would disengage at low speeds. I assured him we were not complaining about that operation. We see and feel that, but it is nowhere near as disconcerting as the free fall feeling when it happens at 35 mph. In full accordance with Murphy's Law, it never happens when driving with the tech in the car.

    Has anyone had any action from Toyota other than attempt to explain away this issue? Is this still considered "normal" behavior?
  • mimersmimers Posts: 7
    I was told by Toyota Customer Relations to contact Toyota's legal department. I have also filed a safety complaint with Consumer Reports, which they were quite interested in, and they recommended the following:

    You may also want to share your experiences with the following
    organizations, which may be able to provide you with information and/or
    offer assistance:

    1. Center for Auto Safety, 1825 Connecticut Ave NW, Suite 330, Washington,
    DC 20009-5708. The CAS compiles information on defective automobiles,
    ranging from transmissions problems to paint problems. If you wish, you
    may send them a letter sharing your experiences with them. Should they
    have any information on your particular automobile, they will forward it to
    you, along with helpful information and advice within 10 days from date of
    receipt of their letter. They ask, but do not require, a $.60 SASE to help
    keep their costs down. Or, you can visit their website at
    http://www.autosafety.org.

    2. Council of Better Business Bureaus, Inc. at 4200 Wilson Boulevard,
    Arlington, VA 22203; 1-703-276-0100. The Council of Better Business
    Bureaus, the umbrella organization for the BBBs, also provides programs and
    publications for consumers, and helps to settle disputes with automobile
    manufacturers through the BBB Auto Line program.

    3. Your State Attorney General's Office, which helps to resolve individual
    consumer complaints, conducts informational and educational programs, and
    enforces consumer protection and fraud laws. You can find their telephone
    number in the blue section of your telephone book.
  • wwestwwest Posts: 10,706
    Were I having the brake problems yawl are describing the first action I would take is HARDWIRE the ABS pumpmotor/relay circuit to the 12 volt battery posts with good heavy duty electrical cables and NO fuse, maybe a 100 amp circuit breaker.

    Maybe even replace the control relay with one that has heavier duty contacts, or 2 pole wired in parallel.
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