car stopped running, 4 codes pulled

Patrick Wong is the expert on these things. First code seems to be defective brake light switch, second code could be a couple of things, refer to the following.

Brake-Related Warning Lights On | PriusChat

Third code P0A607 is not valid, last code depending on "info code" of numbers could point to the transaxle. Really need to know the info code to pinpoint since that code points to more than one thing.

See info revealed here.

P0AA6 Code / 526 Information Code--need help! | PriusChat

FWIW, a google search will reveal codes for you.

Try searching with keywords like "Prius DTC P0A60" without the quotation marks.

Hope this helps you. Sorry I can't be more helpful than I am at this time.

 

Change the juice in the tranny.

 

I would suggest making sure the 12 volt battery is fully charged or consider getting a new 12 volt battery. It seems like the cold weather causes problems with these 12 volt batterys and when it gets low it sets off lots of codes and the engine does not engage.

I do not believe it is a problem with the transaxle. Here is a thread with my experience: P0A4B Code, Transaxle/Generator | PriusChat

Although I did not experience the same codes as you, it was a P0A code concerning my transaxle.

 

The P0AA6 in the GenII is a show stopper (but not in the GenIII). As pointed out in the above link, this is due to an electrical insulation fault in the HV system. It can happen that the MG1 or MG2 winding insulation can get damaged and allow a slight leakage current to flow, which will trigger the DTC.

As one poster mentioned, changing the transmission fluid would be a last ditch effort to see if any improvement could be had. But if it is due to winding insulation breakdown, that won't help.

If the mileage in the Combination Meter is not coming on, then it is likely that the CM is a candidate for replacement under the extended warranty program.

 

The first code seems to be a defective brake light switch. That's likely the reason the car's not turning on. Do me a favor, hit the start button without pressing down the brake and see if the indications are the same with and without pressing the brake. I would think you have to get that problem fixed first before you can decide anything.

 

1. You need to confirm what the third code is, since what you have written is not a valid DTC.
2. I agree that the brake light switch needs to be replaced, since that is the significance of P0571. The switch has two parts, one switch is normally closed while the other switch is normally open, when the brake pedal is up. Those two switches reverse their status when the pedal is depressed. Use an ohmmeter to confirm the proper functioning of that switch.
3. P0607 is pointing to a problem with either the engine ECU or the hybrid vehicle ECU. That might be a bogus code which may go away when the other DTC are addressed. If not, then one or the other ECU needs to be replaced.
4. P0AA6 points to a high voltage ground fault which could be anywhere in the high voltage circuit, including the traction battery, the traction battery ECU, the high voltage battery cable, the inverter, the transaxle, or the air conditioner compressor. The three-digit info code is needed to pin down the problem further, or else the components can be disconnected and a megger used to determine where the high voltage ground fault is located.

As a temporary measure, you can disconnect the 12V battery for a few minutes to clear the codes, then try to start the car. Once P0AA6 is logged, the hybrid vehicle ECU will not permit further restarts and the DTC must be cleared again or the root cause of the high voltage ground fault repaired.

 

Not necessarily, If one part of the switch was working correctly but the other is not, you might still be able to shift gears. Can you run the test I spoke of in my previous post and report the results here?

 

One of the possibilities for generating the isolation fault is for one or more of the HV battery modules to have a small amount of electrolyte leakage, which could indicate some impending failure there. But the additional code info is needed to pin point that.

 

You can disconnect the 12V battery as long as you realize that any existing DTC will be erased. No worries though, I am sure they will reappear quickly enough.

The brake switch testing and replacement is a fairly simple and inexpensive thing to do, I suggest you do that first.

 

You are assuming that these problems happened at once. More likely, a minor issue like the brake pedal switch developed over time and the owner tried to ignore it until the switch failed solid. It is possible that there are only two issues: the brake switch and the high voltage ground fault.

At 152K miles, the car is at design end-of-life so you should not be surprised by a transaxle failure, or any other failure for that matter.

What I would do:

1. Fully-charge the 12V battery and if it does not hold a charge, replace it.
2. Measure resistance on the brake switch in the open and closed positions, and replace it if needed.
3. Figure out where the high voltage ground fault is, by disconnecting the various high voltage components and using a megger to detect a ground fault. Since the dealer pointed to the transaxle, I would start by disconnecting MG1 and MG2, and using the megger on the three-phase AC terminals of both MGs. If the ground fault is severe enough, a regular ohmmeter will detect some resistance (less than infinity) from each terminal to ground. Any resistance measurement less than infinity is "fail".

 

Replacing the transaxle fluid is a Band-Aid and might temporarily get rid of the ground fault if due to a stator winding in the transaxle losing insulation. The theory is that the old transaxle fluid has accumulated metal particles which makes the fluid more electrically conductive than new transaxle ATF. Use only Toyota ATF WS, four quarts.