Triangle of Death VSC and yellow ! lights on with no check engine P0A09 CODE

That is pointing to Hybrid battery failure usually evidenced by hearing the Hybrid Battery cooling fan run in the back seat and the charge cycle on the MFD of the Hybrid battery showing quick changes from full to depleted.

The Lan codes you pictured are rubbish and only have to do with the manufacture of the MFD Touchscreen itself they have no diagnostic property.

Only foolproof way of knowing this diagnosis for sure is to get the codes read the car has logged by a Hybrid Code Reader. These are not found at Autozone unfortunately usually all they can read is generic codes. The dealer usually charges one hour diagnostic labor to pull the codes and usually finds one or more of the 28 battery modules has failed. You are out of warranty on the Hybrid battery as they offer 8/100K
on non carb states.

There are many after market sources for new Hybrid packs. Becoming big business.

 

DTC P0A09 means that the hybrid vehicle ECU thinks that the DC/DC converter is not functioning. Make the Prius READY and measure voltage across the 12V battery or at the positive dedicated jumpstart terminal. If you see much less voltage than 13.8VDC, that is evidence the DC/DC converter has failed and therefore the inverter will need to be replaced. The manual also suggests verifying continuity of a wire that connects the hybrid vehicle ECU to the inverter.

Given that you are selling and servicing so many Prius, I suggest you subscribe to techinfo.toyota.com so that you don't have to rely upon a third party technical opinion...

 

Just had the exact same problem on a 2008 Prius.
We were finishing a long trip. Lights came on. We took it to the nearest dealer. He couldn't identify the problem.

We have less than 100k on the car.

 

Still having this problem. Triangle, VSC light and brake light. On the screen there is a message,

"There is a problem with the transmission "P" lock mechanism. Park your car on a flat surface, and fully apply the parking brake."

We live in Dallas, this problem seems to happen randomly, but almost always after or while driving at high speeds in hot weather. most times you cannot turn the car off right away. We have to press the power button repeatedly.
We usually wait a while and the lights go out, except for the red triangle. If the red triangle stays illuminated, it's never on the next day after resting overnight.

We have taken this car to two different Toyota dealers and both have told us that there are no codes, so they don't know what to do. I did replace the 12v battery on the recommendation of the dealer. That didn't seem to make any difference.

Thanks to anyone that can help.
Dan

 

Pictures

 

Toyota not knowing what to do? So where do they expect you to go with this problem? ford? Nissan? I know, sounds ridiculous and crazy

 

That error message is the most classic sign of low 12V battery voltage. You need to check the actual voltage of the battery. Give it a complete charge with a battery charger. Make sure the bolt to the car body from the negative lead is fully tight. Check the voltage both at the battery itself and at the jump terminal under the hood, and with the car off and in ready mode. You should see ~14V in ready mode.

 

I'll check it out. Thanks.


iPhone ?

 

I had the same problem a couple times as the OP. My shop who takes care of us could not find a thrown code. My 07 Prius had no other symptms from what I could tell other than the warning lights. Seems like fluke of some sort in my case.
I

 

Please i need help. I had my hybrid battery changed because it was faulty and also it had the Red triangle and check engine light on but after i changed the hybrid battery the check engine light went off but the big triangle never left , because of a P0A09 code for the inverter converter, i changed the inverter converter and my car won't go into "Ready mode". Please help me

 

welcome!
please start a new thread, and provide as many details as possible. such as:

how many miles

how long have you owned her

what is the cars history

who changed the battery

what battery was installed

how is the 12v health

are the fob batteries new

who changed the inverter

what device are the codes being read with

and etc.

 

This is actually an easy fix 90% of the time. The blue wire in the fuse box plug at the top of the fuse box gets corroded. If you see blue powder on this wire, it is probably the problem. I have a picture to show how I fixed it. There are other similar examples of this fix on P.C. It has worked 3 times for me so don't say you disagree. I'm tired of posting a known fix and some book guy says it doesn't work.

 

I have a 2007 Touring Edition with over 170,000 miles on it. I got my hybrid battery replaced with New Prius Battery in 2019. Everything was fine but in the last few weeks my Twelve Volt battery was failing and I needed to frequently jump start the car. I had no warning lights other than tire sensor and oxygen sensor (mechanic most likely damaged the sensors). I got the starter battery replaced at Pep Boys today. After the battery was installed I got these dreaded lights again. The hybrid battery seems fine as I can accelerate and get “traction” just fine. The voltage seem fine too when I checked it. I think I remember that small single wire that attaches to one of the 12v battery terminals got damaged and was later repaired. Maybe the technician damaged it again?

 

That sense connection would be a reasonable thing to look at, as it is one of the suspects for a P0A08.

It is not so clearly connected to P0A09, so there might still be something more going on. But if you already are suspicious about the sense wire, might as well start there. Then just follow the workup steps in the manual for P0A08 and P0A09 if that hasn't turned out to be the whole story.

 

Well I took the Prius back to Pep Boys today and that single white wire was all good. Turns out it was a thicker black cable with a metal connector was completely disconnected. It plugs into the battery terminal modular thing very close to the side of the car. He tighten something on the cable and we both heard it click back into place on the black plastic module. He gave it and all the other cables and wires a quick tug to make sure everything was secure. He put everything back together and I started my car and the amber warnings disappeared but the red triangle remained. We cleared the OBD codes and it promptly went out. I drove it home and had no problems. l am sorry I do not have more details because the Pep Boys technician did this so quickly.

Now I just need to figure out how to get the shielding around the oxygen sensor fixed. Find the time to get to Costco to get TPMS sensors setup or calibrated or whatever needs to be done after they have been replaced. Because apparently that was not done correctly to begin with. Finally I have to investigate the disappearance of my spare steering wheel that I placed in the garage and never saw again. I wanted to get it modified to have brighter LED lighting.


Hopefully all of this will be helpful to someone else in the future.