Brake Issue

Discussion in 'Clarity' started by Sandroad, Dec 5, 2018.

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  1. Sandroad

    Sandroad Well-Known Member

    This afternoon my wife had a brake issue. She was parked in a parking ramp and needed to move to another space. When attempting to back up, the brake pedal went almost all the way to the floor (maybe actually all the way, it was hard to tell) and the red Brake and Brake System warning lights on the lower right dash came on. When that happened, the car would not move but the parking brake was not on. Turning off and restarting the car once didn’t help, but the second time got the pedal back to a normal feel and the warning lights turned off. The car was then drivable.

    Subsequently she remembered one other time the brake pedal was not normal. Further, 2 days ago we heard a loud squeal from the car that lasted 2-3 seconds. Hard to tell just where it was located, but it could have been at one of the front wheels.

    I plugged in my code reader and found DTCs C1555 and P0004. The chassis code may be for an ABS sensor (?) but the P code makes no sense because it appears to be for the fuel system pressure.

    The earliest our dealer can get us in is 5 days from now, so we’ll hope the brakes are ok in the meantime. My guess is a defective/damaged ABS sensor. We'll have all the software updates installed at the same visit.

    Does anyone have a set of the DTCs? I can Google those individually, but I wondered if there is a list of any Clarity-specific codes?
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  3. Robert_Alabama

    Robert_Alabama Well-Known Member

    I tend toward taking risks, but I would really caution you about driving a car much with a known brake issue, especially one where the brakes might fail completely (or locking up completely). If I had to have a car before getting the Clarity serviced, I might rent one rather than taking the chance.
  4. Sandroad

    Sandroad Well-Known Member

    I agree! We'll use our Land Cruiser and guzzle a bunch of gas for few days. We don't normally drive it around town. I'll have to remember how to pump gas; it's been a while. ;) I was sure surprised when the service writer told me the next available appt was next week. I would have expected them to be willing to check out a brake issue, at least for a diagnosis, much more quickly. But, it was the same service writer who told my wife our car never needed an update of the navigation system because "Roads don't change." I've learned to keep expectations low with service depts.
    KentuckyKen likes this.
  5. insightman

    insightman Well-Known Member Subscriber

    Wow, having the brake pedal go to the floor and then having a pair of restarts fix the problem would make it seem that the brake pedal cannot operate the brakes without assistance from the electronics--could that be true? Here's the Service Express document describing the Clarity's braking system.
  6. Sandroad

    Sandroad Well-Known Member

    Thanks for that service document. Looks like we have brake-by-wire, including a pedal feel simulator for when regeneration is slowing the car. The fluid pressure appears to come from a servo that pushes the pistons in the master cylinder, depending on computer input/output from pedal position and pedal force indicators. I'm going to go look at the brake pedal tomorrow and see how the physical linkage works. That will help clarify for me what "going to the floor" means with the Clarity.
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  8. Sandroad

    Sandroad Well-Known Member

    I did look at the brake linkage this morning and there appears to be a physical rod that goes through the firewall from the brake pedal into the back of the master cylinder. I have no idea if that's connected to the piston in the cylinder and can produce fluid pressure by itself, or if it requires the electronics/motors to build pressure. Hopefully some of both, with normal braking function requiring the electronics/motor but with a fail-safe of a mechanical connection as a last resort. The diagram posted by @insightman from @AnthonyW doesn't seem to explicitly show the mechanical connection. I have no idea why the pedal went to the floor yesterday, but I know that on some models of Toyota if the brake booster pump fails, the pedal goes to the floor with almost no braking effect.

    The parking brake is operated by a switch and a motor, not a mechanical linkage operated by the driver. So in an electrical failure of any type (fuse, switch,motor, wire, etc), or a mechanical failure of the mechanism, you are SOL with the parking brake.
  9. lessismore

    lessismore Member

    sounds like there could be air bubble from master cylinder to brakes, especially when the issue happens occasionally. agreed with other posters - drive another car instead while waiting for the dealer to check it out. if they cannot find anything wrong, they can easily replace the brake fluid to make sure. good luck!
  10. Sandroad

    Sandroad Well-Known Member

    The dealer reported no mechanical issue with the brakes. He said to my wife: "Sometimes these things just fix themselves." However, they have had the car now 2 full days trying to get the recalls done. Apparently the parts were not available at the Honda parts depot. They may come in tomorrow and they will get them installed by Thursday. If that's the case, they will have had the car 4 days to do the updates. :eek:
  11. insightman

    insightman Well-Known Member Subscriber

    Your dealer should heed this ancient truth from an ancient version of Microsoft Word:

    MPower, leehinde and Sandroad like this.
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  13. MNSteve

    MNSteve Well-Known Member

    This is the second post I have read about recalls. I see zero on all the web sites. What's the deal?
  14. Sandroad

    Sandroad Well-Known Member

    Last October, Honda grouped the software updates and some defective parts into some sort of service campaign. I'm not sure about the specifics. Although someone else on this forum called it a recall, my VIN shows nothing official for a safety recall. I should not have used the word recall in my post above.

    Here are the open service bulletins that I THINK are included:

    18-089: 6SV00, PHEV Abnormal Water Temp Reading
    18-091: 6PH00, Range Display Incorrect
    18-090: 6VT00, EVTC Failure Misdirection
    18-096: 6CW00, Emissions Warranty CD Product Update
    18-097: charging problems (sensitivity to power fluctuations at public chargers)
    Remarksman likes this.
  15. Atkinson

    Atkinson Active Member

    Sandroad is correct, the braking system is power assisted like most modern cars.
    With no power assist, the driver can still use the brakes manually although more significantly more effort is required and stopping distance is increased.
    Page 123 of the manual lists the process.
    You have to scroll a bit to get the braking part.

    Emergency Power System Stop
    The POWER button may be used to stop the power system due to an emergency
    situation even while driving. If you must stop the power system, choose one of
    the following operations:
    • Press and hold the POWER button for two seconds, or
    • Firmly press the POWER button three times.
    The steering wheel will not lock. However, because turning off the power
    system disables the power assist the power system provides to the steering
    and braking systems, it will require significantly more physical effort and time to
    steer and slow the vehicle. Use both feet on the brake pedal to slow down the
    vehicle and stop immediately in a safe place.
    The gear position automatically changes to (P) after the vehicle comes to a
    complete stop. Then, the power mode changes to VEHICLE OFF.

    The dealership approach to this issue leaves something to be desired.
    Maybe a call to corporate Honda?
    At least to let them know the cavalier attitude received for a safety issue on a new car.
    I get it that there was no mechanical issue, but there sure was an electronic issue with the power assist.
    Remarksman likes this.
  16. MNSteve

    MNSteve Well-Known Member

    I don't recognize the abbreviation "EVTC". Traction Control?
  17. Sandroad

    Sandroad Well-Known Member

    electronic vehicle temperature control
    electronic vehicle traction control
    electronic variable timing control

    I wonder?
  18. Ray B

    Ray B Active Member


    NHTSA ID Number: 10145430
    Manufacturer Communication Number: A18-090
    Service bulletin - There is a software problem in the PCM, which may cause the MIL to come on with DTC P26A3 (electric water valve malfunction), DTC P100C (electric VTC motor speed signal circuit malfunction) and/or P0010 (variable valve timing control [VTC] malfunction).​

    I am guessing this is the flaw that caused some episodes of excessive RPM that some people have reported.
    Remarksman likes this.
  19. MNSteve

    MNSteve Well-Known Member

    Is it asking too much to write these in English, rather than in Acronym? Apparently "PCM" is the Power Train Control Module. I am guessing that in this context "MIL" is being used to mean "Malfunction Indicator Lamp". So the way I read this is that it's not causing anything more than a bogus indication on the instrument panel.
  20. lanb

    lanb Active Member

    What parts exactly are they waiting on ?? Aren't all the SB's so far just software updates ?
  21. Atkinson

    Atkinson Active Member

    Now that would be a nice find.
  22. Sandroad

    Sandroad Well-Known Member

    We got the car back today. The dealer had it Mon-Thurs. It had taken them 5 days to fit in the appt to begin with. The service writer apologized and noted the service dept is learning along with me about the Clarity.

    They found nothing repairable about the brakes and no stored trouble codes related to the brakes.

    They did 4 updates (descriptions in a post above) for our VIN:

    The 18-089 update required a part, a CPU assembly 06999 that is part number 06796-TRW-A00
    The 18-096 update is also a “part” because it’s a new warranty CD.

    So, we’ll see how it goes.
  23. KentuckyKen

    KentuckyKen Well-Known Member

    Could you post back after enough driving time to let us know what if any differences you noticed after the update? And why did they not do the 18-097 sensitivity to charging fluctuations update?
    I really want to know since my car acts so perfectly that I have been reluctant to get the updates except for the HV range. We’ll consider it your Christmas present to us all.
    Merry Christmas!!
    Last edited: Dec 13, 2018

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