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2002 Prius "Hybrid System Warning Light" just came on

Discussion in 'Generation 1 Prius Discussion' started by SteamRollerCC, Aug 26, 2012.

  1. SteamRollerCC

    SteamRollerCC Junior Member

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    I was driving to work yesterday and all of a sudden the "Hybrid System Warning Light" just came on the screen. I didn't notice anything different and drove it the same way. However, when I checked the energy monitor screen, the battery was low on charge. It came back to normal in about 5 minutes, but the light is still lit up.

    I also have a first gen 2002 prius. Everything seems fine. What could be causing this?
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Odometer reading?

    This might be your first warning that the traction battery is about to die. The battery gauge will typically show 50% or 75%. If by "low on charge" you mean the gauge showed 25% or 0%, that is not a good sign.
     
  3. bwilson4web

    bwilson4web BMW i3 and Model 3

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    One of the first recommendations is to get a Prius aware ODB scanner so you can dump the stored codes and look at other metrics:
    • $150 Scangauge II - requires programming XGAUGEs to see the interesting stuff.
    • $500 AutoEnginuity - requires a laptop but comes with everything needed to see what is going on
    • $1,200-1,500 TechStream-Lite - requires a laptop and shows everything but needs a subscription service
    • $?? TechStream-Lite (3d party) - same as above
    Without the codes, we're flying blind.

    Bob Wilson
     
  4. SteamRollerCC

    SteamRollerCC Junior Member

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    *Update*
    The warning light shut off! Everything seems normal, if it happens again, I'll take it to the dealer to see if I can at least get it diagnosed.

    Patrick Wong It's never went to 25% -0% though this was the first time I saw it to about 50%, then it went away back to around 85% where it usually is.

    bwilson4web Where can I get the ODB scanner? What is it? Sorry, I'm completely new to owning a Prius. I actually brought this used 3 weeks ago with 86,000 miles.
     
  5. SteamRollerCC

    SteamRollerCC Junior Member

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    Here's what I mean about the battery charge:

    [​IMG]



    [​IMG]

    It goes from about 75% to 50% and back. Other than that, everything seems normal.
     
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    50% to 75% is normal. FYI, the Classic gauge only has five possible readings: 0%, 25%, 50%, 75%, and 100%. Start to worry if you see any readings below 50% or above 75%.
     
  7. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Onboard Diagnostic Bus (OBD) is built-in to just about every car since the 1990s. It is a connector located near the steering wheel that shares diagnostic information from the car control computers. An OBD reader plugs into the connector to read out these codes along with a lot of useful engineering data. When a shop says they are going to put the car "on the computer" they mean an OBD reader.

    Many of us came to the Prius with hands-on, experience working on other cars. But unlike simpler cars, our Prius is operated by a suite of computers. For example, the accelerator is a spring and a 'stereo volume control' connected to the Hybrid Vehicle Electronic Control Unit (HV ECU) a computer. This computer operates the transmission and sends commands to the engine ECU and battery ECU to make the car accelerate. Without an OBD device to read out the engineering data, it would be very difficult to understand what is going on. But having one that 'knows the Prius' allows us to understand what is going and translate it into lay terms.

    The OBD reader also lets the owner see what the 'shop' sees. The beauty of PriusChat (and similar web sites) is there are helpful people who will translate OBD error codes and engineering data into an understandable description of what is going on.

    Bob Wilson
     
  8. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    Hello SteamRoller,
    I have found that my Gen I is a little finicky and will periodically give erroneous/false warnings/DTC's. Here's the way I handle them.

    If the car is running fine and getting good gas mileage, I write the codes down, reset the codes and drive on. If they don't come back, I move on. If they do come back (consistently the same codes), I know I have a real problem. So far I haven't had any come back consistently and haven't had a code in a long time (since I changed out my 12V battery). I would recommend checking your 12V battery as well b/c they've been known to cause intermittent errors/DTC's when weak. Other than that, drive it, enjoy it and learn all you can about it. The best advice "I" can give you is to not freak out when you get a code and be wary of what a dealer tells you.

    Case in point, my wife ran the car out of gas and it threw a bunch of codes. I was new to the Prius so I put gas in it and it started up and ran fine. Just to make sure there was no damage, I took it to the dealer and they stated I needed a new charcoil canister and a new gas tank ($1100 total). Since it was running fine, I declined the service. 3 years later, it is still running fine on the same charcoal canister and gas tank that "needed replaced".

    Gen I's are a little tempermental but, mine has been extremely reliable (and still is).
     
  9. SteamRollerCC

    SteamRollerCC Junior Member

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    Thanks guys!

    My warning light has not come on since. It's been driving great with no noticeable problems thus far. One thing I do remember before that warning light came on, is that I washed my car... but it was later that I realized I pointed the water hose toward the "hybrid vent". Do you think that could've caused the problem? I've been much more careful about washing/waxing it ever since.
     
  10. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    I guess there is an outside chance that that could have caused it but, the more likely cause is, you put the car in gear "D" or "R" b4 the engine started. If you do this, you will get they symptoms you mentioned and the car will be low on power. Its hard to say what caused the lights/warnings. Did you check the health of your 12V battery?