Red Triangle after car sits for 2-3 days

Hello

My 2005 Prius has an issue where it will throw several dash lights after it sits undriven for 2-3 days. It will usually start up OK, but shortly after starting it will get the red triangle, the traction battery light, and brake system warning light. The car will drive fine in this condition until it is turned off, then it will not start. If I use my OBD2 tool to check for codes I don't get any codes, but clearing the codes will normally allow the car to restart. Occasionally I have to disconnect the 12V battery to get it to restart. Once I get it to start with no codes and drive it a while the condition doesn't come back, unless it sits for a few days undriven. This car is my daily driver and as long as I drive it every day it doesn't have the problem. I just put in a new yellow top Optima battery since the old one was 5+ years old and the problem came back after I didn't drive for a few days. I think this is related to something draining the 12V battery while it sits, but no idea what it could be. The car is stock with exception of a stereo mod to add in an Aux port. It is on it's 3rd traction battery with about 350K miles.

Thanks for any ideas on where to start.

 

Hello

I just tried starting the car after not driving it since Sunday and it ran for about a minute before it threw the red triangle, brake warning light (yellow circle with !), and the hybrid system warning light in the center console display (red car with !). In this condition the car continues to run until I shut it off, but won't restart until I use my cheap OBD-2 scanner to clear all codes. It usually doesn't actually throw a check engine light, or have any OBD-2 codes stored that I can see.

I used to have the a tech-stream cable for my laptop but seem to have lost the cable so I can't get currently see any other codes.

I am planning on ordering another tech-stream cable and will post results after I get it. I will also check the voltage, and amp draw since I suspect this is due to something draining my 12V battery. Appreciate the great suggestions and will let you all know what I find.

Thanks!

 

Thanks - I have another techstream cable on order and will check for the P0AA6. If that is the problem would it only manifest after the car sits? I can literally drive this car for months with no codes, as long as it doesn't sit for more than 2-3 days. It has been doing this for several years and I have just lived with it, but getting ready to hand this car down to my 16 year old and would like to get it fixed.

I did check amp draw on the 12v, and it was about 14 miliamps, so seems to be in the normal range. I will check voltage on the 12v for the next few days and see if it is dropping.

Thanks

 

I finally got the new techstream cable and got it working with my Laptop and got the following codes:

P0AA6
C1256
C1259
C1310
B1421
B1200
B1207
B1271

I clicked on the P0AA6 and got detail codes 526, and 612.

Any ideas on where to start with this are much appreciated. One other issue that may or may not be related is I noticed the area under the spare tire and inside the 12V battery well is catching rain water. I am assuming I have a leaking hatch seal or a clogged drain, but its holding about an 1" of water in both areas. Going to shop vac it out and see if I can figure out how it's getting in.

Thanks

 

I decided to pull the battery yesterday and open the case to see if I could spot a leaking cell or other issue. The battery was a mess inside the case with several cells apparently leaking and bad corrosion on terminals (see photo). I was planning on trying to replace bad cells but given the damage I am shopping for a replacement battery. Any suggestions on who sells a good replacement product? This car is going to be a 1st car for my daughter to drive for a year or 2, then likely it will be sold or donated, so looking at used or reconditioned vs new.

 

Thanks - I think I will try a repair on this battery before I give up. I took the bus bar loose today and checked the individual voltages. I got a low of 7.48v, and a high of 7.78v. Most were around 7.6-7.7V. What voltage readings would indicate a bad cell? I didn't see any obvious leaking cells though there is a lot of gunk around the terminals.

Thanks

 

I tried testing the voltage of each cell to the case and I found 15 modules with more than 1V, and a few up around 5-6V. I am thinking that with this many cells leaking I need to bite the bullet and get a new battery. Thanks for the help in diagnosing the issue.