Main Battery trouble after period of disuse

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Robinbjerke, Jun 14, 2016.

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  1. Robinbjerke

    Robinbjerke New Member

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    Morning all,

    This is my first post, though I have been trawling the forum for a while now. Last year I took over a late 2005 model Prius T3 from my Aunt. It had been sat idle for a number of months as she had bought a new car.

    Initially I bought a new 12V battery which started everything up. The engine fired straight away and the HV battery got charged up from its one or two bar status.

    I am currently a trainee in the merchant navy, and this led me to have to go off to sea for 3 months after having used the car for about 6 months to commute to college with no problems whatsoever. During these three months I forgot to unplug the 12V battery and my wife neglected to run it every so often. Long story short I get home and she's dead. I just bought a 12V charger and recharged the 12V battery, but the system is now showing me only 1 bar for the HV battery as well as the warning triangle and the main battery problem light upon start up. The ready light will not come on.

    I have spoken to one of the toyota service guys at the most local toyota garage, and he said initially that charging the 12V fully would probably solve the problem. If not, he said there might have been some ECU fault codes from when I tried to start the car with a weak charge on the 12V battery which might not have been cleared and might be causing the problem.

    I was hoping someone might know of a way to clear ECU fault codes on a G2 Prius without having to pay 170 dollars for one of their guys to drive out and do it for me? Also, has anyone encountered a similar problem before and if so how did you resolve it?

    It must be said that if there is an actual failure of the HV battery I'm probably going to have to scrap the car, as I can't afford the $1000+ of either recharging using specialist equipment or replacing the battery.
     
    #1 Robinbjerke, Jun 14, 2016
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Disconnect the 12V battery for a few minutes, then reconnect. That will clear DTC logged by most ECUs (except the SRS and skid control ECUs).
     
    #2 Patrick Wong, Jun 14, 2016
  3. PapaWill

    PapaWill Member

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    I have question for master Patrick Wong, if he is so willing... I have a friend with an '06 that was dead on the road, ostensibly because of HV battery. Was towed to her house. I came to look at it. Will not go into diagnostic/ready mode. 12V battery is fine. All lights work and so on but when I try to get diagnostic or ready, I get nothing! Unplugged the 12V battery for a few minutes, still nothing. Advise PLEASE! How to get to source of issue?
     
    #3 PapaWill, Jun 8, 2019
  4. bisco

    bisco cookie crumbler

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    how many miles on her?

    best to tag patrick, reply to his post, or pm him.
     
    #4 bisco, Jun 8, 2019
  5. TMR-JWAP

    TMR-JWAP Senior Member

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    If you press the power button while your foot is on the brake, does the dashboard turn on or stay dead? MFD dead?
     
    #5 TMR-JWAP, Jun 8, 2019
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    If the Prius will go into IG-ON mode, where the warning lights on the dashboard are on, then you should be able to retrieve the logged DTC. However, since you disconnected the 12V battery, most DTC will have been erased (except DTC logged by the skid control or SRS ECUs.)

    What means are you using to retrieve the fault codes?
     
    #6 Patrick Wong, Jun 9, 2019
  7. Coolride17

    Coolride17 Junior Member

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    Here's something I found from testing for parasitic drain on the 12v system. Every so often if I didn't drive the car the 12 would be dead, maybe 3 days. Well I had a 1.5 amp drain on the dome fuse, doors closed, all lights off . If I put the dome switch in off position, drain's gone. Back in auto , drain was back with no lights on. Only thing the looked a miss was one bottom door light bulb didn't work. I popped the cover off, and it wasn't plugged in. I plugged it back in, and it worked. Guess what, no more drain in auto position. Dead battery solved. Guess the system knew a bulb was unplugged, and stayed in some kind of testing mode when car was off?
     
    #7 Coolride17, Jun 9, 2019
  8. PapaWill

    PapaWill Member

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    Don't know how many miles on it.... can't get dash to light up. I am using TSI. IT will NOT go into diagnostic OR ready mode, so tech stream is useless. MFD does not work. Thank YOU for your consideration!
     
    #8 PapaWill, Jun 9, 2019
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

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    OK, lets focus on the combination meter and the MFD. They receives 12V power from the following fuses: 10A GAUGE, 15A DOME, 15A ECU-B, 7.5A ECU-IG, 7.5A ACC.

    Check the fuses by removing each one by one, measuring continuity across the fuse, then replacing it.
     
    #9 Patrick Wong, Jun 9, 2019
  10. TMR-JWAP

    TMR-JWAP Senior Member

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    Papa......If this "death of the car" occurred while driving, your symptoms are exactly what happens when the AM2 fuse blows. When the AM2 fuse blows, it is usually due to the inverter cooling water pump failing.

    See this thread for photos and more information...

    Total Shut Down- No Warning Lights, Please Help! | PriusChat
     
    #10 TMR-JWAP, Jun 9, 2019
    Last edited: Jun 9, 2019
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