2006 Prius Red Triangle, Brake Warning, VSC

Had since new a 2006 with 344,000 miles. Do nearly all the work on the car myself and understand it well (except for this problem). Replaced evaporator at 250,000 miles (lots of fun pulling that dash apart!). Replaced the HV battery with a remanufactured one at 320,000 as a precaution as the original was charging and discharging rapidly. Replaced the 12 volt battery in Jan of 2015 with a Toyota OEM. Been through around 2 or 3 inverter pumps. Inverter pump working normal. Brake actuator replaced at 300,000 miles by Toyota under their extended warranty. All fluids replaced every 50k.

About three months ago I noticed if the car sits for a day or two without running, sometimes I would get the Red Triangle, Brake Warning, and VSC lights. On a generic code reader no codes but able to clear everything. If I drive (20 minutes or so) or the codes will not reappear unless the car sits for a few days as mentioned. Checked for a parasitic draw with my DMM by getting inside the car and closing all doors. A few amps for perhaps 15 seconds or so then .03 amps, reasonable draw for a car sitting off. Took the car to the dealer (gulp!) and they stated the 12v battery checked good. Then they offered a $90 'diagnostic check'. I said no thanks thinking they were full of it and bought a fresh (only one month old and checked the charge before install; good) AGM replacement battery. Car sat for 36 hours after I installed the new 12v battery and same codes this morning (egg on my face). Codes always come on about 1 minute or so after cold start. At work, cleared the codes and car drives fine with no codes. MENU screen shows 14.4 volts for 12v battery indicating to me it's charging.

I realize a multitude of items could be causing this but any ideas from anyone else with a similar situation would help. Saw a long thread about a fellow in the UK with a similar problem. Turned out to be his HV cooling fan connector was corroded from a rainwater leak inside the cabin.

But with my issue it 'seems' to be related to a 12v battery as the car has to sit for a day or so to get the problem. But with two batteries, one almost 3 years old and a new one going bad? Possible but I would assume not likely.

 

Had that replaced under warranty about two years ago. It's quiet and not charging every few seconds as it did when the original one was failing. Not that I'm ruling it out though... And the lights I have are the yellow Brake Warning, Red Triangle, and VSC. Thanks

 

Shouldn't I be getting an ABS light also? Only have three: Red Triangle, yellow Brake Warning, and VSC.