Only 38mpg and lights on the dash related?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Iketorz, Oct 29, 2018.

  1. Iketorz

    Iketorz Junior Member

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    BTW Update: Still have the dash lights but I noticed while cruising something that doesn't jibe with the regenerative braking not working: On a freeway cruise this car only gets 35-40mpg. Again, no codes other than the one c1345 left that's triggering the lights.
     
  2. sam spade 2

    sam spade 2 Senior Member

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    At what speed ?

    A code for the ABS brake system likely will NOT have an impact on the fuel efficiency, unless maybe a caliper or two is stuck.
    But when a car gets enough age/miles on it that one thing fails, some other things usually are not far behind.

    You may have more than one problem developing.
    ALL problems will not set a code immediately.
     
  3. Iketorz

    Iketorz Junior Member

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    I appreciate the ideas. I generally cruise at 140-160mph which is why I gave a mpg range to reflect steady cruise mpg at a range of speeds I drive, since nobody ever drives just one set speed. Is that good mpg for 140-160mph?

    As I indicated before this car doesn't have stuck calipers and the wheels spin pretty freely. Since it's a Toyota I don't think "age/miles" really applies to non-wear items at 105,000 miles. This isn't a Chevy from the 1970s or a 2018 Chrysler with five miles on it.
     
  4. Mendel Leisk

    Mendel Leisk Underfoot

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    Is that a typo??????
     
  5. sam spade 2

    sam spade 2 Senior Member

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    While I also think that Toyota's are generally good, they don't defy the laws of physics and some things fail just due to age.
    Ruling things out just because of an assumption is not a wise thing to do.
     
  6. Iketorz

    Iketorz Junior Member

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    Oh it's not an assumption; it's experience with lots of different models. I've been working on cars for 25 years. In my experience almost no Toyotas I've owned or worked on have needed more than a couple wheel bearings and a set of CV axles in the first 150,000 miles, wear items excluded. So yeah, hybrid or not it would be a big surprise for this Prius to be eating something serious. I'm guessing this comes down to something easy like a sensor, but it's of course been elusive so far.
     
  7. Iketorz

    Iketorz Junior Member

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    I was being facetious for fun. Unless I cruise at 100mph and am somehow baffled by how that affects my gas mileage, discovering what speed I cruise at when I say I get 35-40mpg on the freeway in a car that's supposed to get 48+mpg isn't ever going to be the silver bullet here. But yeah I typically cruise at 70-80mph, like everybody.

    I am interested what speed the EPA tests their cars for highway mpg though. It seems like people here regularly exceed that 51/48mpg figure.
     
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  8. Eddy Connelly

    Eddy Connelly Member

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    The biggest reason your mpg is affected will be due to the fact that the regen brakes are offline. Your ICE is the only thing charging your hybrid battery. The computer won't let the state of charge go below 40%. Once whatever is causing your regen brakes to be offline, you should definitely see an increase in mpgs.
     
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  9. bisco

    bisco cookie crumbler

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    generally speaking, region braking would be controlled by ab ecu
     
  10. sam spade 2

    sam spade 2 Senior Member

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    Yes it IS an assumption, since it is based on really limited experience........as compared to the tens of millions of cars on the road and the billions of miles driven every year.

    And I've got about double your experience.

    And just because "car model X" has been really good for the past 15 years, does not necessarily mean that EVERY individual vehicle they make will be equally as good.

    Some major trusted manufacturers have produced some real clunkers over the years.
    And I think there were a couple of Toyota's in there too.
     
  11. sam spade 2

    sam spade 2 Senior Member

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    In most cases, "the EPA" does NOT test the cars.

    They specify how the tests are to be done and trust the manufacturer to do it right.
    Sometimes that trust is misplaced.

    AND......the published figures are only ESTIMATES.
    Some people exceed that and some don't.
     
  12. Iketorz

    Iketorz Junior Member

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    I appreciate the input about what wasn't correct about what I wrote. I guess I'll Google the actual answer for how the tests are performed.
     
  13. Grit

    Grit Senior Member

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    I generally cruise at 240-260 mph so my feedback will be biased.
     
  14. Iketorz

    Iketorz Junior Member

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    Looks like the EPA hwy (highway) test only peaks out at 60mph, and it's only above 50mph for about 80% of it. That's a lot slower than your leisurely 70-80mph cruise down an open interstate, so I can see why my mpg would be lower than the 48mpg EPA hwy figure for my car. It seems like a 2-lane country backroad with no stoplights or stop signs would be a lot better approximation of what the EPA cycle does.

    Doesn't change the fact that my car is getting way worse mpg than both EPA city/hwy estimates, nevermind that it seems like everybody on this forum with an unborked Prius gets at least 45mpg on average, and quite a few it's more like 55mpg. Still working to find the answer.
     
    #34 Iketorz, Nov 12, 2018
    Last edited: Nov 12, 2018
  15. sam spade 2

    sam spade 2 Senior Member

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    Your car is 8 years old.
    You live in Florida where A/C (or windows open) is required about 10 months of the year.
    And EVERYBODY likely does NOT get above 45 MPG.

    It might be normal under your circumstances.
    But it might not be too.
    Just don't worry yourself to death over it.
    Either way, there might not be anything (or much) you can do about it.
     
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  16. ChapmanF

    ChapmanF Senior Member

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    For most things, the Repair Manual (the "RM" tab once you've signed in). That contains the troubleshooting and diagnosis procedures for all of the codes, as well as the mechanical work procedures for removing, installing, overhauling, and replacing things. In the old days when dead-tree versions were available, that first, diagnosis/troublshooting part would be volume I and the mechanical execution parts would be the following volumes, but now it's just all the RM. I doubt you will end up thinking that the RM is "vague to the point of being pointless or seriously underexplained the wide implications of a single trouble code." ... the diagnostic part has a section for each code, usually from one to eight or a dozen pages, in a consistent format that starts by explaining the "detection condition" for the code (the exact conditions and sensor inputs that lead to the code being set) and then go on with steps for troubleshooting to pin down the exact cause.

    But as far as the rest ... the New Car Features manual (the "NCF" tab) is important because it's the one that lays out what all the things in the car are, the names for them, what they're doing there, what function they provide and how they do it. The RM typically starts from the assumption that you know that already, so typical complaints about the RM leaving too much stuff unexplained usually come of not having perused the NCF first.

    The electrical wiring diagrams ("EWD" tab) are your friend for anything electrical. They include not just schematics but physical routing and locations, connector identification and part numbers, etc.

    Some of the others are more specialized. The Collision Repair ("CR") manual is for repairs you can make if metal cutting / welding / brazing and such are things you might actually do. All the ordinary jobs you can do with wrenches and drivers are covered in the RM.

    -Chap
     
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  17. Iketorz

    Iketorz Junior Member

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    I appreciate the in-depth rundown on all that. Seems like it's pretty comprehensive stuff!
     
  18. Iketorz

    Iketorz Junior Member

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    So after Mendel hooked me up with the manual I've been going through things on and off for a couple months to fix this. It's not fixed yet, but based on the car refusing to complete the linear solenoid valve initialization it's making me think that either a faulty ABS/brake actuator or faulty skid control ECU are preventing that from happening, unless I'm just screwing up the procedure.

    The procedure I'm using is using paperclips in the DLC3 socket (aka OBDII plug), turn the car on, tap the TS/CG (4/12) pins together 4 times in 8 seconds or less, then turn car off, connect the pins together, turn car on, let it run through depressing all the brakes on its own, then turning it off. After that it shows code 1345 (through my scanner) "linear solenoid valve learning undone" but seemingly doesn't recalibrate. That's the only code it has. Again the 4 lights on the dash were allegedly precipitated by the previous owner having the car aligned, which turned on the lights (I have paperwork to prove that).

    Incidentally the car's average MPG is up to 43-44mpg now. Best tank is 47.7 which I've never come close to matching again. That involved drafting trucks on 400 miles of freeway at 70-75mph. I've verified from some videos on the internet that in 4 months of owning this car it has never had functional regenerative braking. I'm interested how much better my mpg will get once that's functional.

    Weirdly finding a used 2010-2015 skid control ECU seems damn near impossible but strangely the brake actuator is available everywhere.
     
    #38 Iketorz, Jan 25, 2019
    Last edited: Jan 25, 2019
  19. eunique

    eunique Member

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    have you checked Toyota All Parts in Rancho Cordova, CA? they are Toyota specific dismantlers and will ship for cheap.

    Note 9 ?
     
  20. Iketorz

    Iketorz Junior Member

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    I really appreciate the tip. I just emailed them so we'll see what they have to say. I'm crossing my fingers the price is reasonable. The 2010 is right on the cusp of being old enough to show up in the junkyards near me and those junkyards sell things like these computers for $25-45. Considering I'm not even sure the skid control computer is broken, I'm much more comfortable taking a chance on a cheaper part.

    As is I've managed to get decent MPG out of this car even with totally non-functional regenerative braking, it's not the most pressing, but I'm pretty intrigued whether I can manage 55-60mpg out of this car since I got 53.2mpg on a 65 mile trip a few days ago.
     
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