Low 12-Volt Battery Apply Parking Brake Securely...

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by Insighter, Jul 16, 2018.

  1. Insighter

    Insighter Active Member

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    I just tried to go for a ride in my '17 Prime Advanced. I opened the door and noticed the warning on the multi display that the charge port was open, so I unplugged the charger, closed the charging port door, got in and pressed the power button with my foot on the brake.

    Everything seemed normal until this point. I got a message on the informational display that said "Low 12-Volt Batter Apply Parking Brake Securely While Parking See Owner's Manual". I took a photo of the message. As you can see, my hybrid battery is fully-charged.

    I've never had a problem like this before. I last drove my car 19 1/2 hours ago, and that trip was without issue (it was EV mode all the way, as are most of my drives). I left the car plugged in to the charger and didn't touch it until just now when I tried to use it. I did not leave any doors open or interior lights on (my car is in my garage all night, and I'm in and out of the garage many times during the night and day). Nothing was connected to my Prime that would draw power from the 12v system.

    I have had some modifications made to my Prime (that I've posted about here), but the last of those was made months ago and there have been no problems since they were made. My dash camera was not on (it does not get power when the car is off). I have had no prior issues of any type with the 12v system. I did search these forums but couldn't find anything on point involving this warning message.

    Questions:
    (1) Does anyone know what might be causing this? I read the owner's manual, but it wasn't helpful.

    (2) Why does the warning message include that warning about the parking brake? I never use the parking brake when I'm in my garage. Does that somehow affect the 12v battery?

    (3) If I leave my car in the "READY" mode, will the hybrid battery charge the 12v battery (so I can make sure it is recharged now)? I know I can't do that for too long as it will drain the HV battery.

    Prius-Battery-Warning.jpg
     
  2. Elektroingenieur

    Elektroingenieur Senior Member

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    In Toyota’s Repair Manual, for the message you quoted, the Problem Symptoms Table for the electronic shift lever system lists only “Auxiliary battery is discharged or voltage is low” as a suspected area. The table refers to an “Auxiliary Battery Low Voltage” troubleshooting procedure, which in turn refers to a more detailed on-vehicle inspection procedure for the charging system and auxiliary (12-volt) battery.

    With the car turned off and not charging, have you measured the voltage across the auxiliary battery? Could one of the aftermarket accessories have malfunctioned and be drawing current continuously?
    Without a good 12-volt power supply, the hybrid vehicle ECU might not be able to operate the parking lock mechanism, so you could try to shift to park (P), but the lock pawl may not actually be engaged. In this situation, if you want to be sure the car won’t roll away, you need to use the mechanical parking brake.

    As the New Car Features book says, when the message is displayed:
    • The parking lock mechanism may not operate.
    • The hybrid system may not be able to be started.
    • Even if turning the power switch off, the power switch may change to on (ACC). In this situation, applying the parking brake may enable the power switch to be turned off.
    • Even after charging the auxiliary battery, the message may be displayed until the shift state is changed from park (P) to a shift state other than park (P).
    If the hybrid system, DC-DC converter, and auxiliary battery all OK, and there isn’t an extraordinarily high load on the 12-volt electrical system, then the auxiliary battery should be charged when the car is in “READY.” Considering the symptom you’ve reported, however, I’m not sure I’d count on this without further investigation, at least to check that charging voltage (13 to 15 volts) is present at the battery terminals.

    Both the Repair Manual and New Car Features are available by subscription to techinfo.toyota.com.
     
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  3. Insighter

    Insighter Active Member

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    Thank you very much for that detailed information! Someone stole my multimeter a few years back. I need to get another one. But I frankly don't know how to check the voltage across the auxiliary battery when the car's turned off. I'm pretty sure I can get one to measure voltage from a household outlet or a battery itself, but that's about the extend of my knowledge in that regard. I never learned how to use all of the features of a multimeter.
     
  4. Insighter

    Insighter Active Member

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    I forgot to answer this question. I don't think anything could be malfunctioning and drawing current because the things I had installed only have current when the car is on, or are just wires that would need something connected to them to draw current (and are safely capped off). The only modification to the car I don't trust is the KARR alarm the dealer installed. It's already had two connections failures.
     
  5. FuelMiser

    FuelMiser Senior Member

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    What I notice in this picture is you are not in READY mode, but ignition is ON, so all power is coming from the 12V "aux" battery. I like to use a plug-in voltmeter to monitor the 12V level. Before you get to READY mode, you are seeing the voltage level of the "aux" battery alone. After READY mode is engaged, you are seeing the level of the 12V charging voltage that comes from the traction battery.
     

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  6. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    It's pretty straighforward: pop and raise the hood, set the multimeter to Direct Current Volt mode, red lead to positive (red capped) battery terminal, black lead to grounded bare metal, something like a bolt into the frame, or the engine. If your multimeter is not auto-ranging, you'll need to also set it to an appropriate scale.

    The reading you get will something along these lines:

    upload_2018-7-17_6-22-49.png

    From this page:

    The 12volt Side of Life (Part 1)

    The multimeter will give you the at-rest voltage, a good first step, still it falls short regarding battery "health". Something like the Solar BA5 (or various similar iterations) are better in this regard
     
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  7. bisco

    bisco cookie crumbler

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    the car charger should charge the 12v while charging the hybrid battery. if you charged at the beginning of the 19 1/2 hours, and the 12v is actually discharged, something must be discharging it. either a light on, or a short.

    does the car not start?
     
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  8. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Two checks would clear things up a lot.

    1. At the least a check of at-rest voltage. Or better, an electronic load-test with Solar BA5 or one of it's kin.

    2. Connect the multimeter up in ampere mode, in series between the battery negative post and ground. Basically: disconnect the negative cable at ground, then clip one lead to that cable, and the other to a good ground on the car. Then just let it sit and see what kind of milliamperes you're reading. To protect the meter, start with the meter in ampere scale, there should be no reading, then switch to milliamperes.

    Doing this with ours, I got around 16~18 milliamperes, with spikes to around 40. This is basically the background load on the battery. If it's signif higher, something is running your battery down excessively.

     
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  9. Insighter

    Insighter Active Member

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    Hi Bisco - Thanks for weighing in. I would have thought that, too. However, I've read other posts here that said (or that I believe said) that when a Prime is plugged in to charge, it is only charging the hybrid battery, and does not charge the 12v battery. I think the posts I read said that previous plug-in Prius models did charge the 12v battery, but not the Prime. Can anyone confirm this for me?

    I am 99.99% sure I left no lights on because when it didn't start, I didn't flip any light switches, so they still would have been on when I restored power. Also, if a door is left open, my (exterior) puddle lights on the turn signal mirrors would have stayed on, and I would notice that going in and out of the garage. I'm not sure how long they stay on, but they stay on when the doors are open. Also, I would have noticed an open door when I first got in the car, and that would have immediately concerned me.

    I believe it wasn't starting. I have one of those portable battery-pack jump starters, so I connected it and got it to start that way. I then left it in "READY" mode for over 30 minutes before I drove anywhere.
     
    #9 Insighter, Jul 17, 2018
    Last edited: Jul 17, 2018
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  10. Insighter

    Insighter Active Member

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    Thank you for that information. I'm looking at that BA7. I know it has some features you wouldn't use on a Prime, but I might use it on a regular car sometime, and it's only about $7 more than the BA5.
     
    #10 Insighter, Jul 17, 2018
    Last edited: Jul 17, 2018
  11. bisco

    bisco cookie crumbler

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    that would confirm the dead battery if it jump started. to know if it is charging the 12v with the hybrid, if you get a voltmeter, the 12v will read high while the car is charging.

    you're not the first person with a dead prime 12v, so it might just be defective and under warranty.
     
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  12. Insighter

    Insighter Active Member

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    Hi Bisco - Thanks for that information. Please clarify, if you can, whether the Prime charges the 12v battery when the Prime is plugged in. I believe it only charges the hybrid battery.
     
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  13. bisco

    bisco cookie crumbler

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    i can't. i thought it was the same as pip. perhaps they changed it because the battery is in the engine bay.
     
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  14. Insighter

    Insighter Active Member

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    Okay, I think it doesn't. I think it lacks some sort of 12v converter that would be necessary. It's a real shame they didn't include that. If I'm wrong about this, and anyone reading this knows differently, please respond.
     
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  15. bisco

    bisco cookie crumbler

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  16. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Yeah it seems like the BA5 is in short supply, maybe phasing out? If you're looking in Amazon, I've noticed a lot of alternatives, apparently better displays, and you can connect to your computer with USB, print out.

    OTOH, the BA5 (or BA7) are tried-and-true. I've had my BA5 for 2~3 years now, and it's still fine, only the leads are slightly twisting, lol. It's rudimentary, but works. I'll sometimes take a shot of the display with my phone, if I want to keep a record.

    To directly answer your question, I think I'd go for the BA7. I suspect the extras are more useful on a conventional car, with regular charging system, but you may encounter some of those. For $7 difference snap it up.
     
  17. Elektroingenieur

    Elektroingenieur Senior Member

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    There is indeed such a converter. In New Car Features, Toyota writes, “Using the sub DC-DC converter built into the electric vehicle charger assembly, the auxiliary battery is charged with the minimum necessary power to reduce power consumption.” The Repair Manual has a few more details; see the procedure for diagnostic trouble code P1CCD96 and the explanations for Vehicle Control History codes X0543 and X0544.

    That said, I don’t know about the output capacity of the sub DC-DC converter. It may be enough to keep the car from draining the auxiliary battery while it’s charging, but it might not be able to support much more in the way of parasitic load, much less recharge an auxiliary battery that has already been discharged.
     
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  18. Insighter

    Insighter Active Member

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    Thanks for that! I'm all but certain there was nothing left on in my Prime, so I'm beginning to suspect my battery is going. I took it to an Autozone to have it tested, and they said it needed charging, and that they couldn't test the battery unless it was fully charged.
     
  19. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    I suspect when the car is off there's no charging of the 12 volt by the DC-DC converter; allowing that could deplete the hybrid battery.
     
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  20. bisco

    bisco cookie crumbler

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    correct, that's why i posted the theory in #7, that after the charging was done, something drained the battery. but maybe not.
     
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