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Uh-oh... "Can't Engage EV Mode" error

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Uncle GroOve, Jun 6, 2006.

  1. Uncle GroOve

    Uncle GroOve New Member

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    Hiya guys.
    Still in love w/ my '05, great mileage on our congested roads despite an occasional "heavy foot" :D

    One bigger problem has popped up.
    I get this "Cannot Engage EV Mode" (in italian it would be "passaggio a modalità EV impossibile") every now and then.
    This happens *despite* a full battery and *despite* the fact that the motor has warmed up to optimal temps (it usually happens when I've been driving 3-4 hours).
    I usually drive the last half mile or so uphill w/ my EV on to drain the battery down to the last bars... (I can do this because I do have the EV button, as I own a EU model). What I do is slow down at the sharp turn at the bottom of the road, press my EV and up I go.
    When I have this problem, not even stopping the car, and (IT guys will love me for this, LOL) restarting the motor helps.
    "It" refuses to engage the EV mode.

    Has anybody had experience of this before?

    Another minor niggle:
    After a minor ride, say 30 minutes - where the IC has fully warmed up - I stop, go shopping for about 30 minutes and return to the car.
    As I power up, the IC insists on turning on, despite the fact that a) it must be still warm, B) outside temperatures are now well above 20 degrees C and c) the AC or other power-suckers aren't on.
    What gives?

    Appreciate your qualified replies, as always!
    Thank you,

    Paul
    a.k.a Uncle GroOve
    Switzerland
     
    #1 Uncle GroOve, Jun 6, 2006
  2. mssmith95

    mssmith95 Michael

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    I have the same problem, and a few others have noted it as well. With mine, it seems more related to temperature then anything else. Everytime I have not been able to engage EV mode, it has been after and hour long commute home. The only thing I can think of is that there is a temperature sensor that is not allowing EV mode until the Hybrid temperature goes below a certain level. I have never actually seen any documents on this, but it seems like the only possible explanation
     
    #2 mssmith95, Jun 6, 2006
  3. Tideland Prius

    Tideland Prius Moderator of the North
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    The engine always has to do a check when you start the car unless you mean it comes on immediately after pressing the POWER button.
     
    #3 Tideland Prius, Jun 6, 2006
  4. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    Draining the battery (even though it's not "drained", just <50%) seems "unhealthy" - rather leaving it at it's ideal charge when starting up next time is less taxing.

    Reason being is that for the first few minutes during warmup, the car "prefers" EV mode even with the ICE running, and will favor the battery unless heavier acceleration is "requested" until at least S2 mode is hit (engine exits retarded timing no load idle). If the battery is nearly drained (1-2 bars), the ICE may be forced out of it's warmup cycle early in order to start charging which is worse for emissions and economy. I'd say you'd force a premature engine startup as well, however I forget that the EU versions don't have the coolant tank for warmup. In the US version, a super low battery combined w/ A/C usage will force the ICE to start before the coolant has had a chance to do it's pre-heat so that the battery can be recharged. EV mode is also "denied" when battery is lower than 3 bars in our case. We don't get messages though, just a double-beep from the system.

    At any rate - I've noted EV mode is highly temperature dependant as well as charge dependant. If it's much more than 90-95F outside (or whatever that correlates to for parked car temps for the interior), it's not going to happen for me. Of course, usually by then most of us want A/C on anyway and high A/C demand (high compressor speed) is enough to supersede EV mode as well.
     
    #4 HTMLSpinnr, Jun 6, 2006
  5. Uncle GroOve

    Uncle GroOve New Member

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    Hi y'all...sory for the delayed response, I was away a couple of days.

    HTMLSPNNR - part of your reply re battery level seems to contradict an older post of someone that was basically stating:
    "drain all your battery because anyway the motor will need to warm itself up [this was supposing the last trip home @ night] the next morning - so you might as well get 2 tasks accomplished at the same time [warming up the motor AND charging the battery].

    As far as the "coolant tank" is concerned I just wonder why wouldn't it be standard on the Eu models as well! This does explain the rather odd ehaviour I had described in the second part of my initial post...

    MSSSMITH95 - You could actually have a point there. But I always thought that EV doesn't really like *low* temps - noth the higher ones.
    In any case I am usually able to engage EV while the A/C is working - if there is sufficient batt. charge.

    Paul
     
    #5 Uncle GroOve, Jun 10, 2006
  6. windstrings

    windstrings Certified Prius Breeder

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    the Car always turns on the ICE unless you engage EV during the startup sequence. ie: hit power, then your ev button before the computer boots up fully.

    but is your Air on full blast or heater that may make the car want to disallow EV?

    Every once in a while mine does that.. I figure the computer sees something I don't and just wants the ICE to run a bit.

    I've been in 95 degree weather after driving the car for 15 minutes and having 5 bars left and it won't let me go to EV.. what gives?.. I figure its no big deal since thats not consistent, there must be hidden issues the computer is dealing with.
    But usually in those scenarious, I've been playing with the air conditioner recently.
     
    #6 windstrings, Jun 16, 2006
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