2008 Prius 237k will not go into ready unless I disconnect the white rectangular plug on top of the battery. Once I do ready comes on and runs fine. A couple of miles down the road I get Red Triangle, VSC and the round brake drum light. Still runs fine,battery charges on screen ,A/C, good mileage (from the screen), brakes etc. Ran test from display screen after sitting for 3hrs. Battery with ACC 12.5v Press Start second time(no brake) to IG ON Drops to 1.9 -12.0v Put foot on Brake for usual go to ready drops to 11.7. Once going it shows 13.9v. AutoZone battery test says good battery. Inverter pump working(Turbulence in reservoir). If I shut off then try to go to ready immediately after driving, ready light comes on flashing but then goes out.
1) Ensure the battery cables are tight at both posts and the negative body ground. 2) There are codes stored. Your coded reader or the store/shop you are using, does NOT have equipment that can read ALL of the Prius codes. 3) Consider contacting member "TampaPrius.com" (Todd) for help. 4) READ the owners manual to understand what the warning lights mean. There is only a parking brake is activated warning light: "BRAKE". There is a brake system warning light. The car is telling you that it has detected a problem with the brake system, that you are ignoring at your peril. You are mischaracterizing this as "round brake drum light," which does NOT exist. VSC = Issue with traction control which is likely related to the brake system warning light.
Then it is the "Master Warning light", "Brake system warning light" and the VSC " vehicle stability control system warning light". Hope that clarifies it. Once in ready If I do not drive far and turn off before those lights come on it will go to ready. Will get codes read by appropriate service center
If you DIY, you should get "mini VCI w/ Techstream" ($25+ at Amazon). Even if you don't DIY, it is a useful tool that will save you the pricey Toyota diagnostic fee of $100+. Techstream is the official diagnostic and maintenance software written for Toyota/Lexus and used at the Toyota/Lexus dealerships. Does NOT matter who you buy from, as there is likely only one or two producers of the knock off cables and software from Panda land. Be prepared for returns b/c their is NO quality control for these knock offs. People have reported the need to order a second cable, since the first cable did not work. The hacked copy of Techstream works easiest on a Windows 32bit OS laptop. Ask friends/family in IT if they have an obsolete laptop (XP, Vista, 7) laying around. They can probably give this to you free of charge. Use this laptop only for Toyota/Lexus diagnostic purposes ONLY. NO email, banking, bill payment, etc, since the software is hacked. MAC install possible, just search.
Thanks tried to get them read at an import shop ( German, Asian) first thing they said was 12v was really discharging fast and needed to be replaced. I did that and have the same issue of voltage drop to below 12v during IG-ON. Will get the DIY from Amazon
When the OP gets the codes read properly he will have a P0AA6 code. That's a high voltage isolation fault. It's the only fault condition that allows the Prius to run fine until shut off and then not go ready.
Had a hybrid specialty shop analyze. Got P0AA6 , C1259 and C1310. Tech checked cells and they were fine.
It would be interesting to know what tests the "Hybrid Specialty Shop" performed. They should have been able to pinpoint the source since your leak is at the point of quickly returning after being cleared. One test uses Techstream and it's sub or info codes to simply tell you the area of the leak. Sometimes there are not any sub codes that identify the leaks source. Here's another test that does not require any special tools or codes readers. It will only work if the fault reappears quickly after being cleared. Here's another video showing how to test the cells for leaks. This guy has awful safety practices. Wear gloves and use an alligator clip for one of the test leads so the test can be done one handed.
Did the first test here once codes were cleared. Went to IGN-ON and the triangle and other lights came up after about thirty seconds. It did however allow it to go to ready. Later I cleared codes again in order to go to ready and drove about 35-40 miles over about an hour before they came up. This AM a new issue came up, No energy monitor display, Climate Audio and info and display setting will come up but no Energy monitor . Car runs fine.