Low battery error codes; water in wheel well.

Best I can figure almost all circuits won't throw a low voltage code unless the voltage dips below 10 volts. I don't think this is happening. 11.5V is typically not a problem under load. If it does not return to 12V when the load is reduced, well then there is an issue. I know the Prius is pretty sensitive to B+ voltage dips. I doubt this is the issue. I'm

Ed, Great tip on the plastic piece. I'll check this out as well as a detailed look at the upper hatch and roof seam.

On the battey, I hear you. So many problems historically tracing back to Prius auxiliary batteries. I had the same problem 2 years ago. To rule it out I take my full charged boat battery and jumper it to the front jump start tab. Clear the codes, and run the car through a bunch of start/stop cycles. Last time I did this it was the battery. This time the codes return. By the way, this is a Florida Prius relocated to Boston.

 

Thanks, I did see this work up. A breadcrumb for the next guy, the IGCT Relay is in the main engine bay fuse box, typically gray, marked on the box top as "P-CON". There is a simple procedure listed to test this relay. I have learned that they can "stick" as they wearout. This delay can cause the code to trigger.

 

Replaced auxiliary/starter 12V battery. Still have codes after reset. Next step is TechStream V13. Awaiting cable. I also checked the IGCT Relay,OK.

 

Replaced auxiliary/starter 12V battery. Still have codes after reset. Next step is TechStream V13. Awaiting cable. I also checked the IGCT Relay,OK.

 

Replaced auxiliary/starter 12V battery. Still have codes after reset. Next step is TechStream V13. Awaiting cable. I also checked the IGCT Relay,OK.

 

I replaced the 12V battery while waiting for the Techstream cable to arrive. Unfortunately, the battery didn't solve the problem. As a matter of fact the problem is broadening, the car will not start and I can't clear the trouble codes. The infamous "P" lock mechanism is happening with the display showing the warning. Could I actually have a Prius with both a bad HV battery and a bad brake actuator with only 82K miles on it? Waiting for the cable to see whats up....

 

I wanted to close out this thread. So long story short, it seems the problem was the HV battery. All trouble codes have resolved. Amazing how a weak battery can throw so many weird codes.

The folks from Hometown Hybrid were very responsive. They ship Fedex Ground, so I knew exactly when the battery would arrive, and the Fedex guy gave me his phone number and swung by to pick up the core when I called. The battery came with a very informative packet of material to help with safety and installation. They do a solid job on the purchase and warranty paperwork and make it easy with DocuSign. So far its a good value in my book at $995 including both-way shipping and a 2 year warranty. TechStream shows the battery in well balanced shape within voltage tolerances as expected.

The only rookie mistake I made was the inter-lock. It threw a P0A0D code on first start attempt. I had not slid the lever down hard enough to engage the safety interlock pins. Luscious Garage has a good video on this, I'm sure its a common mistake.

I'll keep you all posted on how well this battery works out but for now, thumbs up for Hometown Hybrids out of Houston, TX.

I'm still working on that leak in the rear quarter sumps. It should be obvious, and I know where it classically leaks, but damned if I can find it. Finally our Prius is back after a 3 week fiasco. A final note, I have to let the Toyota guys off the hook. They thought it was the HV battery but just could not produce the TS diagnostics to prove it. Regardless, I saved $2500 doing it myself. (yeah, I know its not new cells). Good enough.

 

I did replace the 12V battery and that was not the issue. The issue eventually was solved and was the HV battery. Interestingly when the main battery has issue it can cause various current drain issues resulting in low voltage conditions in the 12V circuits and produce all sorts of errors. Even more strange for some reason it masks a P0A08. Once I replaced the 12V with a full charge (13.3V) AGM battery, it cleared some of the c series codes and set off the P0A08 code. I then used TechStream to stress test the HV battery and it was pretty obvious it had issues. Once a refurbish battery pack was installed, all the codes disappeared. Back in business. Good rule of thump is to make sure the 12V battery is charged over 13V. The AGM battery charges higher than the older liquid electrolyte batteries.

I would also use the trouble codes as a starting point not the Bible. You could waste a lot of money simply replacing parts every time a code pops up. Validate a problem before replacing parts.