"Check Hybrid System" light- POAFC fault code- no voltage showing on two battery blocks

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Douglas Kerr, Jan 10, 2019.

  1. Douglas Kerr

    Douglas Kerr New Member

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    Four
    I have a ton of lights on my dashboard. Took the car to the dealer and they advised that I need a new battery at a cost of about $4200. I have scanned for codes and read: "POAFC- Hybrid Pack Sensor Module." I have looked at the battery voltage using Torque Pro and I am seeing that voltage on blocks 1 and 2 show "0 Volts" and blocks 3 and 4 show 25.0 volts, and all others show between 16.6 and 16.8.

    This car had the back window down and it rained and got water into the backseat several months ago, which I guess is the cause of these issues. I took the back seat out when I discovered the problem and it was wet, but I did not see standing water. I dried the area at the time, but the car has sat for five and six days at a time as it is a third car. The car is a 2010 with about 130k miles and has never had any issues, but I am at a loss of how to approach the problem.

    Do you think this was accurately diagnosed by the dealer as a bad battery or does that code indicate the problem is a module? Surely two blocks are not truly 0 volts and two others 25 volts- correct? Should I start by pulling apart the batteries and measuring each module independently? Any advice would be greatly appreciated. Screenshot_20190110-175811.png
     
    #1 Douglas Kerr, Jan 10, 2019
  2. Raytheeagle

    Raytheeagle Senior Member

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    Welcome to Prius Chat (y).

    It appears that a sensor is damaged and probably there is now corrosion or other effects causing the errant readings ;).

    What was the quote from the dealer as they appear to have a large personal payment due and this requires more information?

    So I’d get a second opinion (y).
     
    #2 Raytheeagle, Jan 11, 2019
  3. JC91006

    JC91006 Senior Member

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    $4200?

    If you can watch some YouTube videos and take the battery out, you can see the extent of the damage. Probably some new bus bars can fix your problem
     
    #3 JC91006, Jan 11, 2019
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  4. Douglas Kerr

    Douglas Kerr New Member

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    Thank you for this feedback. I will take your advice and take out the battery and see if anything is obviously corroded or damaged. My hunch is that it may be something other than (maybe in addition to) the battery. The fault code directing me to the battery voltage sensor, seems to contradict the dealer's diagnosis of the battery, but I assume the dealer has all of the tools to properly diagnose. Thanks again!
     
    #4 Douglas Kerr, Jan 11, 2019
  5. ericbecky

    ericbecky Hybrid Battery Hero

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    It sounds like a problem with corrosion in the voltage sensing wires of the orange-colored hybrid battery wire frame. This is the same part that contains the battery module buss bars.

    I would guess the part costs $150-200?

    If you replace it yourself, please buy an inch-pound torque wrench, and use it for properly tighten down the nuts for the battery module posts.
    You will have 28 nuts to tighten and you do not want to get any of them wrong.

    Call me if you want to talk through the repair.
    608-729-4082
     
    #5 ericbecky, Jan 12, 2019
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  6. JC91006

    JC91006 Senior Member

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    I believe I have an extra set of bus bars and sense wires, I can sell them to you if you decide you need them
     
    #6 JC91006, Jan 12, 2019
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  7. Douglas Kerr

    Douglas Kerr New Member

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    Thank you for your advice- it has been extremely useful!

    I went ahead and took out the battery sensor module and I can see that the top two pins are significantly corroded. I found a replacement module on ebay and have placed an order. I should receive the module later this week and will post a status update when I do.

    I am tempted to plug in the new module and see if it corrects the problem without replacing the harness- please let me know if this is a foolish thing to do.

    Thanks again for the helping hand- I am hopeful that this is not going to cost me the thousands of dollars that the dealership estimated- fingers crossed!!!!

    prius module.jpg
     
    #7 Douglas Kerr, Jan 14, 2019
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  8. brad hirata

    brad hirata Junior Member

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    did the replacement module solve your problem? I'm having the exact problem. thanks
     
    #8 brad hirata, Nov 22, 2019
  9. brad hirata

    brad hirata Junior Member

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    Just to follow up, my sensor had corrosion like the above picture. A used sensor from eBay solved my problem.
     
    #9 brad hirata, Dec 3, 2019
  10. Grmichael

    Grmichael New Member

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    Hey, I‘m getting the same POAFC code. Not sure if you guys were able to shift gears but I can’t. I’m only able to shift gears and drive when ICE comes on. I have the check hybrid system message and I’ve tried resetting it many times with no luck, as soon as I start the car the message is back. Do you think it’s safe to drive like 10 miles a day for a couple of days in this state? Because of the COVID-19 the car was sitting outside for like 20 days. It has 95k miles on it. I’m thinking to order the (Hybrid Battery Control Module Voltage Sensor) on eBay and replacing it. I honestly cannot afford to spend anything more than $200 right now it’s been a never ending nightmare here in NYC so we’re financially fu***d. Please let know if I should go for it. Thanks and be safe!
     
    #10 Grmichael, Apr 20, 2020
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