Shorted MG? Codes pulled. May need transaxle.

With any electrical or other weird issues with the Prius, always suspect the 12V battery until that possibility is eliminated. Get the voltages with the method in this thread and report them back here just to eliminate this as a cause. Weird stuff happening? MPGs dropping? Test The Battery | PriusChat

 

Hopefully someone will be able to give you some better encouraging and helpful information about this.

As best I know, which isn't much, it sounds very similar to situations that resulted from electrical shorts in the winding of one of the MG's. Apparently one is reported now and then, though not often. As far as I know the fix is replacement. It may be time to start looking for a used replacement from salvage yards. The good news is that it seems many of these otherwise very expensive parts are now turning up in salvage yards at much reduced prices. Keep us up on your progress. It will serve to increase our repair knowledge database.

 

No you clearly stated that in your original post.

It is detecting a high voltage leak usually from a compromised motor winding. The winding coating has failed resulting in arcing in the trans and the system detects a ground fault with that leakage to the chassis. Gen 1's it would shut the car down for safety but gen 2's allow you to drive with the resultant Invert crowbar & DTC.

Peruse this:

Luscious Garage | Hybrid Specialists

Carolyn has nicely documented various degree's of Gen 2 cvt failures. My hypothesis of winding failure results from super duty use or total lack of fluid maintenance. High current demand on MG2 like driving it really hard or alot of mountain work with load. Alas you did not fill out you avatar profile so do not know where you live.

Anything that creates high current demand from MG2 and you have motor windings heating up. This overheated winding failure may be confirmed by dumping the trans fluid and seeing if there is debris or burnt fluid.

But bottom line you are looking at a new cvt. When you replace yours extract mg2 and you should see burnt windings. Many youtubes on it also.

God luck.

 

I don't think the dealer's note about "moisture in the transmission" makes sense. These are well sealed, normally drawing a slight vacuum in use, and would heat up enough to drive out moisture if it somehow got in. There are just a few that go bad, not common, and no real explanation yet. The consensus is to change the transaxle fluid at 30K miles, and every 60K after that. I will do mine more often as I live in mountain terrain. Here is what one swap looks like:

Transaxle Failure | PriusChat

 

Listen to edthefox5, he knows what he is talking about.
I have almost the exact same story; bought a 2008 with 147,000 miles at a really good price. Found out after I bought it that the original owners had it in to the dealer for codes thrown, dealer said trans, they traded it in. The used car lot I bought it from gave me a 3 month, 3,000 mile warranty, but haha, the Prius trans is considered hybrid and wasn't covered.
The dealer agreed to replace the trans with a salvage unit, so total cost to me was $2600. The car drives great now and doesn't have that funny whine/howl between 50 and 60 mph.
Even with the cost of replacing a trans-axle I'm still at Kelly Blue book NADA value with the car, so I'm not too bummed out.
PS, yes the car was driven long distances at high speeds (Texas), high temps (Texas), and in all the maintenance records I could find there was no trans-axle fluid replacement shown.

 

Hi Lam, referring to the speculation of water in the transmission. Even though it's a really long shot, I wonder if it would be worth a try to just clear the code and change the transaxle fluid. Probably not much chance of it fixing the problem, but then again it's a very easy job (akin to an engine oil change) and doesn't cost much to try.

 

My first thoughts exactly uart.

Like you say it may be a long shot, but if it were my car I think I would give this a try first before going through the expense of changing out the transaxle.

 

Check with Steve at Plug In Hybrid Electric Vehicle PHEV (AutoBeYours) to see what he would charge for a tested good salvaged Prius tranny and shipping costs from southern Indiana.

JeffD

 

I'm not sure about your state, but I know in mine it would be fraud to sell a car with a known issue and not disclose it. You may have recourse from the original seller for not informing you of the issue.

 

Is that just for a Dealer, or are you talking private sale as well?

 

I would pickup an ELM327 OBD2 Bluetooth and get Torque Pro for Android device, then see what the sensors are saying. I had a tripped Motor 1 Temp Sensor caused by a leaking upper radiator hose spraying coolant on the sensor.

 

He did see what the sensors are saying. The 2 DTC's of P0AA6 and 1310 say it all.

 

Reading the sensor values and DTC codes are two different things. When my Temp Sensor tripped a code, Torque Pro showed what the readings looked like. You can see if a sensor shows overheating, or an invalid value.

 

It all depends on what was said. If they just said the car is as-is, then it would have been up to you to discover the problem prior to sale. But if you asked if it had any problems, and they knowingly lied, then there may be a liability issue. I am not a lawyer, but I am pretty sure it all depends on what was said (and what you could prove.)

 

Please be advised... I read a similar post in the Gen II forum quite some time ago. I have not been able to locate it. The person who posted the message was having the same problem as you. It turned out that the transaxle oil was never changed and in its state of degredation, was causing a voltage spike or arching, tripping the codes. Changing the transaxle oil and clearing the codes fixed the problem.

The person who posted reported back months later and stated that the codes did NOT come back. Please try this before you waste time and money...

 

Yeah I agree it's really bad form on the part of the seller, I've had similar experiences where a seller must have known about a fault but it's difficult to prove. With a private seller I think you'd be pretty much on your own if you wanted to take legal action. And if they just say "yeah we put some oil in and that problem didn't happen again to us so we assumed it was fixed", what can you do?

BTW. This is not the first post here where someone has bought a secondhand prius and had some sort of major failure within a few weeks. I've been noticing a bit of a trend in these lately. It seems that several of these type of impending faults do give early warnings which some people seem to be using as an opportunity to sell the car as quickly as possible. This almost certainly appears to be the case here.

 

Bad fluid causing arcing? Baloney. Never saw that post. Show me.

Only thing that can cause arcing in the trans is a compromised winding. Crack or burnt spot in the conformal coating of the winding. Usually caused by overheating of the winding. That quickly turns hilarious and does a nice flame out under load burning a very big area around it.
The Gen II being the tough little car that it is will continue to drive (throwing codes along the way) until either the Inverter finally fails or the winding goes open. Either way driving it with a ground fault is hard on the Inverter.

If degraded fluid causes arcing there would be a million Prius's in the junkyard right now.