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Highlander Hybrid Brake Problems

PFFlyer@EdmundsPFFlyer@Edmunds Pennsylvania Furnace, PAPosts: 5,807
Having an issue with the brakes on your Highlander Hybrid? This is the place to work out a solution!

PFFlyer@Edmunds

Moderator - Hatchbacks & Hybrid Vehicles

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Comments

  • 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.
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