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PSA: Don't let your tank run dry

Discussion in 'Prius c Main Forum' started by PriusCee, Aug 23, 2024 at 10:23 PM.

  1. PriusCee

    PriusCee Junior Member

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    2015 Prius c
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    Two
    Related to the previous thread where I left the AC running for my dog and the tank ran dry, it turns out that while the high voltage/hybrid battery was nearly spent the real reason why I couldn't start my car was it threw a code because it sensed the tank was completely empty. The gas gauge showed zero bars and wouldn't register the 2-1/2 gallons that the tow truck driver added. Once the technician cleared the code the car started normally and the gas gauge went from zero bars to 1 bar of fill.

    How eff'ed up is that?

    So, you run your tank dry and Toyota chose to disable your car. With any other car you would just add some gas and be able to drive to a gas station but Toyota strands you and requires you get towed to a dealership to clear a code.
     
    #1 PriusCee, Aug 23, 2024 at 10:23 PM
  2. fuzzy1

    fuzzy1 Senior Member

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    This is a known issue. We learned very long ago that, at least in Gen3, there has a lockout after some number of attempts to restart without sufficient fuel, or whatever else prevents the ICE from running. This seems to be a protection of the hybrid battery, to prevent drivers from endlessly trying to restart until the battery is drained to the point of not being able to crank the ICE, thus requiring a special hybrid battery charger to bring it back up. Back when Gen3 was still fairly new, there were very few of these chargers in all of North America, needing to be shipped from dealer to dealer as needed.

    Over-drained traction batteries were a very real problem in Gen1 (and maybe Gen2 also?), as drivers continued driving and/or cranking without gasoline trying to reach too-far gas stations, and caused real battery damage. This was much worse than simply draining an easily-jumped-started 12V battery.

    This lockout effectively forced drivers to quit futilely wasting battery charge and go do something else to fix the real underlying problem. Even with a tow and shop service, this is still less expensive and time consuming than what older generation drivers experienced.

    The first member here to intentionally run his Gen3 2010 out of fuel, for engineering tests and curiosity and to report back to us the signs and symptoms and behavior, promptly re-fueled from his spare fuel can and it started right up with no problem. He didn't try restarting before fuel was added.

    Not long thereafter, another member accidentally ran out, then tried repeated restarts without adding fuel, got locked out from further restart attempts, and needed a tow to a dealership where it was reset. A while after that, others discovered that a dealership reset wasn't really needed, as disconnecting the 12V battery long enough to clear volatile computer memory, did the same thing.

    So this car behavior isn't really eff'ed up. It is to prevent you and other from eff'ing up their traction batteries.

    Unfortunately, your Prius Owner's Manual doesn't describe all of this.

    upload_2024-8-23_20-38-41.png
     
    #2 fuzzy1, Aug 23, 2024 at 11:40 PM
  3. PriusCee

    PriusCee Junior Member

    Joined:
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    Location:
    Washington
    Vehicle:
    2015 Prius c
    Model:
    Two
    They could probably deal with this with a message explaining everything you just did. Most people can understand "ZERO FUEL LEFT". The raunchy part is that is the lockout would refuse to recognize that there had been fuel added to the tank until the lockout was removed. It's not like the fuel sensor stops working. How is that not eff'd up to not let you add gas and get to a gas station?
     
    #3 PriusCee, Aug 24, 2024 at 12:18 AM
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