The elusive gear icon

Discussion in 'Clarity' started by MNSteve, Dec 18, 2018.

  1. MNSteve

    MNSteve Well-Known Member

    But the mysterious part for me is that the behavior changes when I can't see any difference in the input - same road, same speed, same weather, etc. "Can't see" is the operative phrase; if all the inputs were the same then the behavior would be the same. Wind is one parameter I know that I can't "see". I think there are others, including the state of charge of the battery and history like what the SOC was when I hit the HV button.
  2. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    I hope you don't mind some kibitzing from someone who doesn't drive a Clarity PHEV, but I wonder if the different regen settings for the car have something to do with this. The Clarity PHEV does have different settings for how strong the regenerative braking is, doesn't it? You might try fiddling with that and see if the car behaves more to your liking in such circumstances.

    That might also explain why different Clarity PHEV cars are acting differently under those conditions.

  3. David Towle

    David Towle Active Member

    Unless you are in sport mode the Clarity brain sets the regen rates to one of four positions based on the need it sees. The driver can't change this.
  4. insightman

    insightman Well-Known Member

    I'm not sure what you mean, "the Clarity brain sets the regen rates to one of four positions based on the need it sees" so I'll describe my understanding of the ways the Clarity might change the regen rate by itself.

    There is only one situation when the Clarity increases the regen rate based on the need it sees: When descending a grade with the ACC engaged, the Clarity engages the level of regen required to maintain the set speed .

    The Clarity will reduce/reject the driver-selected regen rate when the battery is fully charged, when the battery is too cold, when the speed is too great, when the car is being stopped by ACC with LSF, or when "hybrid system protection is needed" whatever that means (see page 391 in the Owners Manual). In SPORT Mode, the Clarity retains the selected regen rate except in one of those 5 situations.
    KentuckyKen likes this.
  5. David Towle

    David Towle Active Member

    I meant what you said, sorry I thought it was obvious. I've felt it go as high as the 2 chevron level when descending a hill, and to 4 chevrons when coming up on a car in ACC. Also note if you manually use regen when approaching a car too fast it sets off a loud alarm and throws it out of ACC, another thing that makes ACC unusable to me.
  6. MNSteve

    MNSteve Well-Known Member

    Possibly. It's a good example of a parameter that the controller might be using that we haven't thought about.

    I don't think that this explains my personal issues, as I never use the paddles to set the regen level.
  7. MikeB

    MikeB Member

    This is just a note for those reading and wondering about this gear icon thing who might be confused as I was. The gear icon is not obvious unless you know what you are looking for. After reading about it here and elsewhere, I was convinced that my car almost never went into engine (as opposed to hybrid) mode. Wrong - I was was looking for the gear icon in the wrong place. Eventually, I looked in the manual. It's a little tiny thing in the energy flow graphic that appears right in the center of the front axle. So, to save others interested in this dimension of our cars the trouble,.....
    4sallypat and Clarity_Newbie like this.
  8. David Towle

    David Towle Active Member

    On o
    jdonald posted a good size picture of the diagram about 20 posts back on this thread (top of page 2 for me)
  9. Ray B

    Ray B Active Member

    By the way, I just tried out my new OBD-II module and logged some data. During a run on HV + ECON mode that included a 5 minute stint on the highway (66 mph max) I found a few interesting findings with regard to the elusive gear icon (Engine Mode). When plotting RPM vs speed you can see a clear linear area where the clutch obviously joins the wheels to the engine. When looking at the data I concluded:

    Between 42 and 66 mph:
    • Engine was on 61.3% of the time
    • Engine Mode (clutch engaged) was on 54.7% of the time
    • When engine was on, clutch was engaged 89.1% of the time
    Just a first test, but I think the "gear icon" may not always reveal when the clutch is really engaged. I will collect some more data and see if those findings are representative or not.
  10. insightman

    insightman Well-Known Member

    I will be astounded if the gear icon and the clutch are not activated by the same signal.
    MNSteve and Gearhead like this.
  11. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Thank you. Apologies, then, for my irrelevant question.

  12. Ray B

    Ray B Active Member

    Agreed, and the only way to figure it out would be to take a video of the dash and cross check it with the data, and I don't have the depth of curiosity to go through with that. Also, I am just assuming the clutch is engaged based on the distinct linear trend in the RPM vs speed data, but I have no proof.

    By the way, I distilled the trip data down to the time I was on the highway, and the revised figure for the time the clutch is likely engaged when the engine is on (above 42 mph) is actually about 95.5%. I will do some more data collection during a couple of trips I will do today and see if that number was an anomaly. By the way, I was not watching for the gear icon (I usually have the range estimates screen up), and was driving with ACC on, set to 65 mph.
    Last edited: Jan 13, 2019
  13. insightman

    insightman Well-Known Member

    What would be great is if someone could come up with an OBD-II code for the lock-up clutch. The only other option is to tap into the wiring harness--not something for the faint of heart. Or is there a fuse just for the clutch that could be monitored?
    Last edited: Jan 13, 2019
  14. KentuckyKen

    KentuckyKen Well-Known Member

    To add a data pointing the clutch issue. On a 500 mile round trip Lexington KY to Elizabethton TN done in HV (55-70 mph) with a nearly full battery, my ICE was on only about 2/3s of the time. This was measured by an inductive hour meter I have hooked up to one of the spark plugs and by using beginning and ending times.
    So my clutch could not possibly be connecting more than about 66% of the time since obviously it isn’t connecting when the ICE isn’t running.
    And it’s probably less since I saw it coming off and on especially on hills.

    But all is bliss since I got 49 mpg and when subtracting the small charge lost (yes it did a good job of keeping the SOC), I still got 48 mpg. And no angry bees even on a long steep hill!
    Love this car.
    I only have one complaint; it’s spoiled me and I will never ever again be able to drive a gasmobile.
    ClarityDoc, MPower and insightman like this.
  15. leop

    leop Member

    I have collected similar data to that which RayB collected and spoke of the results in another thread on this forum. One way to explain the gear icon not coming on when the speed/rpm/throttle data imply that engine drive mode is engaged is the signal to the dash/central display could just be a transition signal. This signal could be missed by the dash/central display unit for a variety of reasons. Then, the display(s) will not be in sync with the engagement clutch. Another explanation is that the ICE is not directly engaged but that the ICE and generator are set to run at the same ICE load as if the ICE were directly engaged. It was said that this mode is less efficient than the direct drive mode but the PCU could get into this mode of operation.

    Since the October update, I think that the gear icon in our Clarity is shown less. However, it also appears that after the October update the energy curve line on the dash display does not always turn from white to blue after the ICE stops running. This is discussed in another thread. One conjecture is that both of these observations point to a transition signal (engine off and clutch engaged) being missed by the dash/central display controller. Again, this is all conjecture. I, too, would like to get access to sensor data for the direct-drive mode clutch.

  16. insightman

    insightman Well-Known Member

    I have a difficult time believing the designers wouldn't use the same on/off signal to activate the clutch and the gear icon. What could be the reason to find some other signal to trigger the gear icon?
  17. leop

    leop Member

    There is no doubt that the PCU has an on-off (or high-low) output that controls the solenoid that engages the direct drive clutch. However, it is very doubtful that the dash and central display modules have direct access to this output. One reason is that this would take a physical line(s) from the dash and display modules to the PCU for each PCU output and would require the various modules to poll for input data. The Clarity electrical system has buses that transmit data between the various modules. It is very likely that the PCU sends out a signal on the bus (or buses) saying, for example, the "direct-drive clutch as been engaged". This is the transition signal that I mentioned. Many such systems also have a way for module to request data from one another (OBDII dongles do this over a vehicles bus or buses). One observation that led to my conjecture is that the blue line white line issue display issue can be rectified by a switch in driving modes and back again (I have only tried HV to EV to HV and I want to try using ECON no-ECON or Sport no-Sport). It is likely that a switch in mode may cause the dash and display modules to send out a request to the PCU for the current data state. Sometime I also want to have the dash and central display modules showing the energy flow graphics at the same time so I can see if both show the gear icon at the same time. Again, this is all just conjecture as we are trying to reverse engineer the Clarity's control system without access to any in-depth direct knowledge from Honda about the design.

  18. MNSteve

    MNSteve Well-Known Member

    But it's what we do. I agree that we need to realize that the validity of our conclusions is bounded by how much reliable data we (don't) have.
  19. Ray B

    Ray B Active Member

    There are a couple of things that make me suspect it is at the very least not instantaneous in its displaying the gear icon. The first is the data that I looked at on my own which shows that when the engine is on above 42 mph, it is almost always at an rpm of 36.5 X (speed in mph), whereas in my few times watching it, the gear icon seemed to be activated much less frequently when the engine was active (maybe 40-60% of the time when the engine was on as a rough guess; certainly not 95+%).

    Second, when I was watching for when it would come on in the past it was at 46 mph. I thought I had read 45 in the literature, so that was when I was expecting it, but the few times I was watching for it when very slowly accelerating, it was 46. But looking at the data, it appeared to start at 42 mph. So if true, I think it is at least slow to update.

    As well there are some other strange things about the driver information displays and HondaLink app. The 20 bar EV charge meter doesn't move from 20 down to 19 bars until the battery is down to 85% charge, and then it drops two bars over the next 8% or so. We all know that the last 2 bars is something like ~15% (0 EV range). So there is a lot of weird non-linear behavior of the EV meter when displaying the SoC.

    Also, the HondaLink app is off by 1 mile typically from the real odometer reading, as well the estimated EV range is off by 1+ from what is shown on the dashboard. Not sure why it would be consistently off like that.

    Anyway, I have no strong feelings about the gear icon, because I almost never notice/look for it, as I don't use that display option. As we all have said, there is no way to know for sure until we break into the wiring or OBD-II PID somehow. It is just some speculation on my part.
  20. Ray B

    Ray B Active Member

    Hi Steve - I have been noticing the same bi-polar behavior for the gear icon (Engine Drive Mode) when I have been on the highway lately. Sometimes it is sticky as glue and stays on no matter what, and other instances it is very stubborn about showing up at all. I had one 10 minute highway drive a few days ago where it came on for the first few miles and then would not return for the rest of it. I plotted the data below if anyone is interested. There were no other big changes happening during the drive - meaning the heat was not turned on, nor were any other electrical drains. The highway had some minor grades, but overall was fairly unremarkable. The grades during the first few miles were every bit as bad as the rest of the drive. Air temperature was 36F; dry conditions; HV-ECON mode.

    In the chart, I plotted the ratio of RPM:speed (blue dots) to find the times where the Engine Drive mode is happening (36.0 - 36.7 RPM/mph; averages 36.35 RPM/mph) - those dots are re-colored orange in the chart. The brief instances around 3:46 and 8:08 were likely just a coincidence of engine speed and vehicle speed, as they only lasted a few seconds, and I didn't notice the icon on the display.

    Just figured I'd pass it along as more OBD data to debate over.

    OBD_Engine Drive Mode.png
    Last edited: Feb 10, 2019

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