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2004 No start, HV battery codes

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by 69amx440, Oct 15, 2017.

  1. 69amx440

    69amx440 New Member

    Joined:
    Oct 15, 2017
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    Location:
    Detroit
    Vehicle:
    2004 Prius
    Model:
    II
    New to the forum here but have been reading through extensively. Need some advice.

    My Dad's 2004 Prius has been sitting for a little over a year. He had a trickle charger on the 12v batter during this time, but the 12v battery ended up failing at some point during the storage. I got a new 12v battery and first hooked it up with jumper cables to get the car moved out to gain access to the rear hatch. The car was not going into ready mode and had all the warning lights on. I did get it to ready a few times after many attempts and was able to start the car to get it to move each time. I left it running each time for some time to make sure the HV batteries were getting charged up. The display showed that they were charging well. Changed out the 12v battery and no longer will ready at all. I don't get the 3 distinctive relay clicks like previously, just one click.

    I got the techstream cable and program for my laptop and got the following codes for the HV system.

    P3000
    P3030
    P3056

    I checked the HV battery and it is at 240V. I have pulled the HV battery and checked all the cells. All but 2 are 7.84-7.93V. One is 7.3 and one is 6.4. I plan on changing out these 2 cells but I am not confident this is even the issue.

    Is it possibly a bad battery ecu? I tried clearing the codes but they come back up immediately.

    Thanks in advance for any help.
     
    #1 69amx440, Oct 15, 2017
  2. 69amx440

    69amx440 New Member

    Joined:
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    Location:
    Detroit
    Vehicle:
    2004 Prius
    Model:
    II
    Also, I have checked all the fuses inside under the dash and the fuses in the engine compartment as well. Also the fuse on the positive post is good.
     
    #2 69amx440, Oct 15, 2017
  3. TMR-JWAP

    TMR-JWAP Senior Member

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    Vehicle:
    2007 Prius
    Model:
    Touring
    You are on the right track. Replace those two modules. They may not be THE problem, but they are 100% A problem.

    P3030 is "Disconnection between Battery and ECU. Listed causes:
    1. Junction Block Assembly (busbar module)
    2. Frame wire #2 (busbar and wire harness)
    3. Battery ECU
    P3000 is "Battery Control Malfunction" and triggered any time there is an abnormal signal from the battery ecu. There can be several subcodes. 123, 125, 388, 389, 603 and probably more

    P3056 "battery current sensor" malfunction. ....maybe you didn't plug in the wire all the way to the current transfomer.

    BUT, first things first, take a look at the CT to make sure its connected. Replace the 2 modules and then try it again. Will probably work fine.

    You probably want to ensure all the plugs are firmly seated.
     
    #3 TMR-JWAP, Oct 15, 2017
    jerrymildred likes this.
  4. jerrymildred

    jerrymildred Senior Member

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    Tampa, FL
    Vehicle:
    2017 Prius
    Model:
    Two
    Welcome. Bummer! Sitting unused is the bane of a Prius battery. :(

    Over the years, we've more or less come to the conclusion that replacing individual modules is like playing whack-a-mole. It would help, if you do that, to buy and use a Prolong Grid charger to balance all the cells before driving the car. You're still kicking the can down the road, but you're kicking it farther. The better alternative is a full set of used, but not as used cells from a totaled Prius. The best is a whole new battery, but maybe not worth the cost for an '04 unless you plan to keep is a long time.
     
    #4 jerrymildred, Oct 15, 2017
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