Skid control ECU goes magically "bad" after I change the 12v battery

Discussion in 'Gen 2 Prius Technical Discussion' started by giarcpnw, Sep 10, 2013.

  1. giarcpnw

    giarcpnw Junior Member

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    Hola,

    First post. Just bought a 2007 Prius from a good buddy. Excellent condition, only 43000 miles.
    Car sat for 3 months while he was out of the country so naturally the 12v battery died. It started giving me the weird errors and low MPG last couple days. I did the diagnostics on it after slow charging it via the maintenance mode and with a multimeter. It was in the 11.4v area. So... I replaced with with a brand new Bosch Type 51. Plug it all in and immediately get the ABS 42, VSC45 and (!) 95 66 codes. My due diligence tells me that the Linera Valve solenoids just need to be initialized. That's a two minute procedure with Toyota's little DTC scanner tool.

    Now they are telling me the Skid Control ECU is bad. I find that a completely suspect that an over priced ecu would simply just die after unhooking the battery. I think they are just trying to make some cash. The car does have an extended warranty on it so it shouldn't cost me anything but this is exactly why I do not trust dealerships. Anyone have this occur. I see lots of posts about bad ECUs and bad brake actuators... All pricey fixes. I thought these cars were pretty much rock solid. hmmmm....

    Thanks.
     
    #1 giarcpnw, Sep 10, 2013
  2. jdcollins5

    jdcollins5 Senior Member

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    Any chance you reversed the polarity while changing out the battery?

    Most 12V battery changes reported on here have just been loss of radio presets, trip mileage, and maybe the window auto-up feature.
     
    #2 jdcollins5, Sep 10, 2013
  3. giarcpnw

    giarcpnw Junior Member

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    No, there is no way I reversed anything. Been working on cars for 20 years and while this is the first cyborg I've ever owned, I'm pretty confident around electronics etc. I still think they are pulling a fast one.
     
    #3 giarcpnw, Sep 10, 2013
  4. Eclipse1701d

    Eclipse1701d Prius Enthusiast

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    Maybe the ECU was shady to begin with. When you changed the 12V it lost all power and won't recover from the hard reset?

    Maybe you should try to disconnect the 12 volt and let it sit awhile. Then, reconnect it and see if the ecu reboots and starts working properly again... Just like a computer, sometimes if you remove power, reset the CMOS and then plug it back in, it starts working. Static buildup or a spike when you connected the new battery may have one of the chips acting funky.
     
    #4 Eclipse1701d, Sep 10, 2013
  5. BFAyer

    BFAyer Junior Member

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    There is a capacitor in the brake system to provide power to the brakes in case the 12 volt power system fails. So unless he hit the brakes with the battery disconnected or the cap is bad, the brakes should have never lost power.

    The cap (power supply) is right next to the 12 volt battery so I would suspect something with that connector.
     
    #5 BFAyer, Sep 10, 2013
    Eclipse1701d likes this.
  6. giarcpnw

    giarcpnw Junior Member

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    Well, I discovered something, my friend had purchased the extended warranty on it for 7 years or 75000 miles. So this was covered under warranty. I still think it's hog wash but considering it is costing me nothing and they get to make 1800 bucks plus labor from Toyota then I understand how they might want to manipulate the system for profit. Somehow they are still charging me 125 bucks for a "diagnostics check" even though I knew the codes ahead of time and i brought it in for the Steering column recall. It's a racket I tell you. This is the new normal I guess as there are just too many systems on this car that a Haynes or Chiltons manual are not going to help with.

    Thanks for letting me vent.
     
    #6 giarcpnw, Sep 10, 2013
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