It pays to know electronics.
This isn’t a new issue but it’s one many hybrid car owners will one day have to deal with nonetheless. Unfortunately, dealerships are likely to charge thousands of dollars to replace hybrid battery packs, a price tag so high they'll no longer be worth fixing. But one Toyota Camry hybrid owner resolved the problem himself for just $10 instead of the $4,450 price his dealer was quoting him. How’d he do it? First off, the owner is the son of a master electrician; he learned the trade from his old man over the years.
And second, he did his online research. Here's what happened: Driving home only two weeks after buying the used Camry (with no warranty), the dash lights starting flashing indicating the brake actuator could be faulty. After doing a bit of Googling, the owner learned the brake actuator would be covered under an extended Toyota recall/warranty, but only as long as the "Check Hybrid System" warning was a false error. He brought the car to a Toyota dealer, who determined the hybrid battery had gone bad and needs replacing. Toyota corporate offered him a $500 repair credit because the hybrid system was within range of the warranty in terms of years, but had exceeded the mileage allowance.
Then the owner remembered reading about replacing single failing battery cells back when he bought a Prius. He figured both the Prius and Camry had the same (or similar) battery pack. He watched an online instruction video (which we included), and soon confirmed the cells were cross compatible.
After removing the battery and long story short, all battery cells were fine and the sole issue was corrosion on the copper connectors. Yes, corrosion was enough to throw off the operating voltages of the whole system. He soaked all 34 buss bars in vinegar, gently scrubbed them with steel wool, and placed them in a solution of baking soda and water to counteract the acidity of the vinegar. He reassembled the battery and put it back in the car. Total cost $10. And now everything is working perfectly.