Can a low 12V battery cause ABS codes? How about revving the engine in Park?

Discussion in 'Generation 1 Prius Discussion' started by KarenA, Oct 11, 2018.

  1. KarenA

    KarenA Junior Member

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    I have a 2003 Prius with 150K miles on it. 3 weeks ago, there were no issues, except that the battery was at the end of its life expectancy.

    Then came the triangle of death. I coasted it home 1/2 mile, looked for codes, and found P3130 and P3125: inverter coolant pump. Because I had my OBD reader out (Innova 340c) and can't leave well enough alone, I also ran through a battery and charging system test. The latter required revving the engine at 2000 rpm for 20 seconds (which wasn't easy with a mushy accelerator pedal) and that's when the ABS and PS lights went on, along with 12 additional DTC's.

    I finally drained the inverter coolant and replaced the pump. Went to start the car today and found a dead 12v battery. (I hadn't disconnected the battery while the car sat and I worked on it). Had it jumped and was told that the battery was at 0 CCA but the "alternator" is fine (I thought the Prius doesn't have an alternator). While I was letting the battery charge again, I bled and topped off the coolant repeatedly. I still had the death triangle but no diagnostic codes. On top of being lazy, I also don't learn from my mistakes, so I did the battery and "alternator" test again. Whammo --"The charging system output is high and can cause overheating"; ABS and PS lights are on and the same 12 ABS codes are thrown: C1271-8, C1281-4 (low output voltage of speed sensors, abnormal change in output signals, faulty master cylinder pressure sensor output signal, faulty front and rear pressure sensor output signals). Then after a couple of times turning the car on and off, the ABS and PS lights went off and there are no codes stored. The accelerator pedal is still mushy.

    Is all of this a glitch from a low battery? Damaging something from revving the engine ? A coincidental bad ECU or charging system? I ask because I don't want to spend > $200 on a new battery if the car is looking at >$1,000 in repairs.

    Thanks all. I'm also happy to share what I learned about changing the pump that I hadn't seen in any threads.
     
  2. bisco

    bisco cookie crumbler

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    very possible that it is the 12v. what is holding you back from replacing it?
     
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  3. Brian in Tucson

    Brian in Tucson Active Member

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    You can connect any 12v automotive battery with a jumper cable. Watch the polarity, of course. Take the car to an indie Prius shop and get a legitimate code scan using techstream. Solve the problem with the charging system before you start on the ABS. Knowing so little about your car, my guess is that the brake booster pump is failing or failed. It's a $1000 part from Toyota, but you don't need to replace it with a new one if you can find one in a junk yard, on someone's parts car, or on Ebay. You can probably find a competent shop by asking the local taxi companies that use Prius's.
     
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  4. KarenA

    KarenA Junior Member

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    Getting a working car after replacing the battery would be a no-brainer, but facing a very costly repair after replacing the battery would be unfortunate. Knowing that these symptoms could be the result of a low battery by itself would tilt me to replacing it.
     
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  5. bisco

    bisco cookie crumbler

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    then find any old 12v for temporary experiment.
     
  6. KarenA

    KarenA Junior Member

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    Alas, I moved the car from the nurturing environs of the Bay Area and Luscious Garage to the backwater of Long Island. No citing of a Prius taxi yet!

    Funny that you mention the booster pump. Mine failed a week after I took my car to a local shop to get the brakes serviced 2 1/2 years ago. The symptoms then were a brake pedal that was almost impossible to depress, and different codes. It's interesting that even now, I don't have any codes for a low battery or a problem with the charging system, and that the ABS codes disappear even though the accelerator pedal stays mushy. If it weren't for the tangible pedal, I could more easily believe that the codes are just an artefact.

    Nice that you have the same car.

    Thanks to you and bisco for the input.
     
  7. padroo

    padroo Senior Member

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    Have your old battery tested.
     
  8. KarenA

    KarenA Junior Member

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    Huh, I'll look into that. Thanks.
     
  9. KarenA

    KarenA Junior Member

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    It's definitely on its last legs. I was expecting to replace it soon anyway, but wanted the car working and having passed inspection before going down that road.
     
  10. bisco

    bisco cookie crumbler

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    i don't blame you. 12v are expensive, then you might have to dump the car and never recoup.
     
  11. Brian in Tucson

    Brian in Tucson Active Member

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    Karen, any junk yards close by? You can get a decent (generic sized) 12v battery to test the car like Bisco suggested.
     
  12. KarenA

    KarenA Junior Member

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    I think a junk yard is in my future. While I’m at it, I can look to replace the headlamp that has a cataract. I’ll report back about my suspicion that I and the Toyota service guy are the only two people on Long Island who’ve ever owned a classic Prius.
     
  13. KarenA

    KarenA Junior Member

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    Back with some clarity and more questions.

    I installed a new 12v battery. The charging system appears fine, although I've hardly driven it. The ABS codes disappeared for the first 5 minutes of driving and then came back.

    The codes are a straight flush if you've got 12 cards:
    C1271-4 (low output voltage speed sensor)
    C1275-8 (abnormal change in output signal of speed sensor)
    C1281-4 (faulty output signals of master cylinder pressure sensor, regulator pressure sensor, and front/rear pressure sensor).

    The brake light isn't on, nor is the main battery light. The car brakes fine, but has subtly more grip and maybe grind.

    I bought a 2-day account for techinfo. Searching on the codes, precious little comes up. I would think the 12 together point to one common problem, but I can't figure out what that is.

    The list I've found of systems that need to be initialized after reconnecting the battery don't include anything about the brakes. Everything else (including the power windows) is working fine.

    I had the wheels aligned before anything popped up, but no codes appeared for a while after the alignment -- definitely not during the 1/2 hour drive home. The codes appeared before I did any work. First sight was when I tested the charging system by revving the engine at 2000 rpm for 20 seconds, while the pump wasn't working and the 12v battery was low. (I will not be doing that again, regardless).

    Any thoughts? Please?
     
  14. bisco

    bisco cookie crumbler

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    speed sensors should be on the wheels? maybe they bumped a harness and loosened it, or there is some pin corrosion
     
  15. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    If the ABS speed sensors aren't working, then regenerative braking isn't being used. It's using friction brakes all the time.

    I agree that there's likely a common element- ABS controller? Or just the fuse feeding it?
     
  16. KarenA

    KarenA Junior Member

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    I'm a little overloaded by the wiring diagrams. Do you happen to know in real space where the connectors might be? (i.e. if I look under the hood, where might I find what I'm looking for?)
     
  17. KarenA

    KarenA Junior Member

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    This is an interesting point. I wonder whether the difference between regenerative and friction braking might cause the difference in sound or feel. The car is driving fine and stopping fine. The speedometer agrees with side-of-the-road readings. The only other thing that seemed off was speedometer readings while I was braking. The 8 mph to 0 range didn't seem right.

    I drove the car today about 30mi round trip total. On the trip back, the ABS codes disappeared, but I still have the ! lights. I tried to get to the Energy display but couldn't get past the warning screen. Otherwise, maybe I could confirm the lack of regenerative braking by the arrows.

    Can I pull out fuses and relays willy-nilly to look at them, or do I need to take precautions? I wish there was something that mapped codes to fuses and relays.
     
  18. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    In a perfect world you'd never notice the difference between the two braking systems. In practice... well actually Toyota got it pretty close to perfect. It's only in situations like this where it comes up. You are probably hearing the difference.

    Regarding fuses- they aren't all the same rating, so be quite cautious to put each one back where it came from. In fact best practice is to only have one out at a time.

    In your shoes I might want the service manual to narrow it down a bit first.

    Interesting that the codes cleared themselves. I know some built-in diagnostics are allowed to clear their own fault flags if enough valid data is later detected, but I don't have a proper list.
     
  19. KarenA

    KarenA Junior Member

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    Thanks for your suggestions. I'll look at the fuses before breaking down and going to the dealer for a diagnostic. I just wanted to be sure that I don't have to disconnect the battery, bury the keys, etc.
     
  20. bisco

    bisco cookie crumbler

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    i think there are connectors somewhere near the inside of the wheel
     
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