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"Freeze Mode", aka how to kill S1a

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Maxwell61, Apr 15, 2014.

  1. Maxwell61

    Maxwell61 Active Member

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    Hi guys,

    upon a key message in this thread:
    HSD behaviour during S1a & S1b warming stages | PriusChat
    where a member described the HSD behaviour in freezing condition at -15° :

    i've got the idea to create a hack to one of the temp sensor of the battery to avoid to drive on the HV during S1a. As a matter of fact, at those freezing temp. the system seems to go in a stage similar to an S1b, but without any electrical help.
    The behaviour has been double-checked by a finnish member of our board.

    The idea is very simple: put a resistor of calculated impedence on the wire of one of the battery temp sensor with an ON/OFF switch on the dashboard. Put it ON for about a minute just to let ICE to warm-up fast and skip S1a.

    The wires are easely accessibile lifting the cover of the HV battery. The red/black connector can be used for a tidy installation of a little box with the resistor, with the benefit of a clean removal just in case.....

    [​IMG]

    [​IMG]

    One of our members dismantled one of the sensors and throwed in the ICE comp of a fridge. Results are that the resistance range seems to be identical to the coolant temp sensor that Priuschat hackers already knows.

    In particular, in a -18° cellar, after 10 mins. the resistance was
    80kΩ ,oscillating about +-5kΩ
    The range:
    79Ω = 140°
    156kΩ = -40°

    Beginning of may we put in a Prius 3 a resistor with a trimmer, to fine tune the minimum resistance that triggers the Toyota Freeze mode, bearing in mind summer temperatures, and test the hack on the road. Later on, a fixed value of resistance can be applied with no need of a trimmer.

    The main advantage of that solution is that the mode triggered has been optimized (on ICE parameters) by Toyota. As has been shown here on Priuschat, with an ICE coolant temp hack the engine will sputter if below 40°: i don't like it. A full hack to avoid S1a would imply this and the hack of the two CAT sensor. Tricky and not very healthy for the engine.
    This particular hack have, then, 2 main advantages: easy reversable installation with no cuttings and a working mode optimized by Toyota.

    Of course the hack is of some interest for people travelling short distance and multiple stops, just to avoid to get 4/6 S1a in a row to go shopping... no need for long distance drives...

    If you can share any comment or ideas, is welcome.
    Max
     
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  2. edwardob

    edwardob Member

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    great stuff...I quess a variable resistor is best.....then it can be adjusted according to time of year....
    The key trigger for is -15 celcis? am I right?
    This things are cheap on ebay ..what kind of variable. range resistance do you think needed.
    I willing to have go sooner than later.
    Thanks
     
  3. Maxwell61

    Maxwell61 Active Member

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    Ed, i don't think a variable resistance is needed.
    The temperature that triggers the "freeze mode" is at present unknown: the test with a variable resistence should clarify which temperature is. The -15° Celsius is just the figure reported by the poster on the other thread.
    Let's say it correspond to -10° C with 20° battery real temp: the resistance should give a -30° equivalent spoofing to trigger the mode. Add some 20° to allow for a 40° real battery temp in hot climate and you'll calculate the total resistance to add to be safely in Freeze mode.

    It would be interesting if some of the northern/canadian Priuschat members could give us a clue about the temperature that trigger the mode, i'm sure many found themselves in this mode in winter.

    If you're willing to go for a variable resistance, i'll let you know the item and the range choosed for testing, when it will be done in may.

    The guy that is preparing the resistance for testing,, installs plug-ins kit here in Italy: having an integrated spoofing system that reads also ICE coolant temp for the plug-in pack spoofing, he will probably create an automatic intervention if the coolant is below 42°. That would be very handy, but i'll rather prefere this very simple circuit, easely remouvable and with no wire cuttings.
     
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  4. edwardob

    edwardob Member

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    how will the car know it can use/charge barrtery if it stays at -15[assuming]degree?
    will the heating up of the battery naturally bring it above -15 and thus the car go back to normal operating?

    i only suggest variable for testing purpose.
    anyway what would i need that would do the job for a crude but working hack?
    just dont know what is needed.....220v...12v...etc....other than that i can do it myself
     
  5. Maxwell61

    Maxwell61 Active Member

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    as i said, the hack is excluded using an ON/OFF switch.
    The car will not use the battery till you switch off the hack.
    Nonetheless, regen braking will recharge the battery as usual, what will be lacking is battery contribution and ICE will not recharge the battery (apparently).
    The natural heating of the battery in no way will put back to normal operation, the spoofed temperature will always be too low.

    So it's you that have to manually switch off the hack after 1/2 minutes from a cold start. If you use Scangauge o Torque, look for a minimum 230° CAT temp.

    About what is needed as hardware, i don't know exactly myself, i'll let you know as soon the parts will be identified.
     
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  6. edwardob

    edwardob Member

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    ok i get it.......
    so do these resister need to be 12v i assume...and just on one of battery temp sensor
    ...i have one i used on vw water temp hack some time back...to give it a go.....it will be crude...but i can tidy it up later
     
  7. edwardob

    edwardob Member

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    here are some interesting extracts prius manual might be helpful
    the temperature trigger may be just under -10 degree cel...If second sheet is anything to go by .....just under hint

    wiring dia.jpg wiring 2.jpg wiring 3.jpg
     
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  8. Maxwell61

    Maxwell61 Active Member

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    Excellent Ed! Yes, it is'nt directly stated, but is quite clear that -10° C is the figure for the freeze mode. The correct figure for the impedence @ the sensor should be then a bit more than 50 kΩ. It should be possible to enterely bypass the actual sensor and go for a fixed resistance of that order. I'll speak with the person in charge and i'll let you know. Can i repost the pics in our forum?
    Also, from the procedure of the manual, it seems to be confirmed that a single sensor manipulation should be enough.

    However, very soon i'll take a Torque registration with graphs to show another method to avoid the battery use during S1a, that i did identified some month ago: in few words, if you put the HSI just over the treshold of Power range upon the first acceleration from cold, and til you remain there, the battery contribution is none and only ICE is pushing.
    This is quite of an acceleration, altough no an excessive one, and if the speed increase too much, you can suddenly go in glide to lower it. So a Pulse & Glide with the Pulse above the Power limit could be an alternative, viable only if you're not in a city surrounding anyway, it tends to get some serious speed. And it costs some fuel. Of course the hack proposed is a much better option...
     
  9. edwardob

    edwardob Member

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    repost away the pictures if you want.....manual has 8000 pages in all...took me a while to find what i wanted..no index..some other pages might be useful ...not sure how to extract pages from pdf file?had to go for printscreen!

    i noticed myself from scanguage that hard acceleration gives same effect...but no good in parking lot....
    i can do it from home because first 500 mtrs is uphill.....but thats about it ..permenant solution is needed

    now if i only knew where to stick the resistor....????
     
  10. Maxwell61

    Maxwell61 Active Member

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    I'll write you in Private message.

    About the location for the resistor it could be few options but i'nt be an expert on this, i'll let you know the solution adopted.
    2 possible points are: 1) on the connector of the wire on the battery 2) creating a bypass in the connector red/black that you can see on the right upper corner of my 2nd pic.
    Of course you will need a bypass with an ON/OFF switch to exclude the resistance.
     
  11. edwardob

    edwardob Member

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    got a timer delay switch ebay once......so maybe something like that could be used......install and forget
     
  12. Maxwell61

    Maxwell61 Active Member

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    not a perfect idea a timer, Ed, the hack should work only if CAT temp is below 230°, with a timer you'll get the freeze mode at any engine start and for a/2 minutes you'll loose any EV assistance.
    But it can be a choice for sake of comfort and simplicity, it should be tested with enregistration of FE with/without.
     
  13. Maxwell61

    Maxwell61 Active Member

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    In actual fact, ther's another prob with a delay timer: if you start the system and just hang around in the car before moving, the timer will start and you'll be late... so, in any case you should have an ON/OFF switch and a manual procedure...

    PS: Btw, Care, maintence and troubles doesn't seems the appropriate thread for the discussion... unless you don't want to see it as a troublesome one :)
     
  14. edwardob

    edwardob Member

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    should be in modifications alright
    your right switch is best,!

    another idea is one of these switch like on microwave just turn it to minute or two setting and it will be semi automatic

    spring loaded switch ...ticking for 2 minute and then a loud bell

    just jesting. but you get idea
     
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  15. Maxwell61

    Maxwell61 Active Member

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    in actual fact is a good idea, as long you can turn it on manually when you need it!
     
  16. edwardob

    edwardob Member

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    would have to manual mechanical microwave type switch....
    eBay..
     
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  17. edwardob

    edwardob Member

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    each sensor has two wires......suppose it don't matter which one I connect resistor too
     
  18. Maxwell61

    Maxwell61 Active Member

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    Hi Ed, i've posed the question to the guy that will work on it.
    Yes, it does'nt matter, as long you don't want to exclude (or substitute) completely the sensor. In the latter case, you should cut both wires.
     
  19. edwardob

    edwardob Member

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    what will you be using to claculate when to switch on off?
    ie......watch ignition on scanguage........cat temp......or just time...

    any one have xguage code for battery temp....for setting this hack up in the first place
     
  20. edwardob

    edwardob Member

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    tried it with 50 ohm resistor........engine does as mentioned. ..but throw a check hybrid sys warning...(clear code with scanguage)...but when I switched back to normal ....... engine stays same and don't return to normal
    have switch off.....which it does with abnormal noise...
    so something missing here. ...otherwise it works.

    may three sensors need to be spoofed??
    any ideas
     
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