2006 enters fail safe after 3hrs of driving

Hi-

I have seen this problem listed before on 2006 models, but the only solution I found was to replace the HV water pump, which has already been done (Jan 2011). I have taken it to the dealer (3 different ones) a total of 4 times now this year for the same issue and have my 5th appointment scheduled for tomorrow.

It just happened again last night around 1am, on a nice cool starry night, on the side of an interstate, in the middle of nowhere, after about 3 hours of driving on the highway at about 65-70mph--Red Triangle, VSC, ((!)), maint req, hybrid system warning light and check engine light all come on with concurrent loss of gas engine power. I pull over, let the car sit for 20 minutes or so, and can start it again. If I try to start the car right away without waiting, the gas engine tries to start, but seems to sputter and runs very rough and then shuts off completely. In either case, Red Triangle of Death stays on, so does maint req, but all other warning lights have shut off.

When I get to the dealer (usually the next day or later in the day after the car sits off in my driveway), same thing every time, they find no trouble codes, and no warning lights.
Attempts so far:
1st visit: told me it was debris in the air intake and replaced the air filter. didnt solve it.
2nd visit: told me it was the spark plugs. replaced those. didnt solve it.
3rd visit: told me it was the fuel injection system. flushed that. didn't solve it.
4th visit: told me it could be software problem. updated and reset ECM. didn't solve it.

I have an electrical warranty and they have checked the 12v and hybrid battery and say they are fine. The car has 64k miles. I plan to drive the car for 3 hours before the appointment tomorrow to duplicate the problem, but if there are any other suggestions out there, please, please let me know.

Thanks so much.
Shane

 

Thanks for the response! Yep, they've said since they can't get any codes and cannot duplicate the problem they can't figure out the problem and can't fix it. I have a voltmeter and will keep it handy for the next occurrence. I'll check the pump and have the dealer take a look tomorrow too. Sounds like I need to have the 12v replaced as well.

 

Well, it's an analog meter, which might not help me here, but, stuck it on the terminals and the arrow stopped a hair below 12v.

 

If this helps at all, I just to put the car into diagnostic mode. Did that and the Prius voltmeter read 12.3v without any load (other than the display screen and dash). 14.6v after I started the engine.

Also, the only warning light left when I started it just now is the check engine light. Last night before I shut it off the Red Triangle was still on along with the check engine light and the maint req'd light.

 

Ok. So I didn't realize there were 3 modes of the MFD check. Now I do. Thanks Ed.

1) Not under load: 12.5v
2) Access Load: dips to 11.9 and then up to 12.3
3) Charge: 14.5 to 14.6

Also, I looked through the butterfly and the throat looks clean...everything I see is the silver color of the engine.

To Richard's question, nope, everything is secure in the battery compartment.

And to Nh70 and Ed, the pump sounds fine (a constant hum, like an irritating large mosquito) and I see turbulence in the reservoir.

 

Thanks! I'll get one of these.

 

So an update:

Took car to dealer this AM. Dealer could not replicate problem. I told dealer I would be happy to try myself tomorrow, but because I would be taking a day off work to drive it 3hours and help them solve a problem they cannot fix without my help, they should provide me with a courtesy towing (ie no charge to me) when my car fails on the interstate. The service rep thought about my suggestion a second and then told me flat out "no, we aren't going to be able to that for you." They want to charge me $100 to tow me back to the dealer when the car quits. Unbelievable.

I called the Toyota customer experience center and lodged a complaint. I'm waiting to speak with the manager at the dealer tomorrow, who had already left for the day at the time of the service rep's call. I am livid. Should I take it to another dealer at this point?

 

Hi everyone. Just wanted to provide what I hope is some closure to this issue.

Long story short, a family of mice had been chewing up my hybrid wiring harness, slowly. The tech said it looked like they had built a village throughout my engine. This problem has been intermittent for almost 2 years. (And yes, I live in the country). I found another post with the same problem here: Mouse chews hybrid wiring harness and causes $1166.79 damage | PriusChat

So the wiring damage apparently caused all these erroneous codes and problems (listed earlier in the thread), some of which would put the car into failsafe mode. Just in case this pops up for anyone else, one of the codes was P3120, info code 250: HV Transaxle Assembly Malfunction, Motor Temperature Sensor Performance Problem, which the tech said he had never seen before, and which the dealer told me was a $7,000 transaxle replacement, because the sensor is somehow built into the transaxle assembly (my car is 2000 miles over the expiration of the extended toyota financial platinum warranty, and well past the powertrain warranty).

Thankfully, they did further diagnostics and found the transaxle and sensor were all good. Another bit of good news is that my comprehensive insurance policy (liberty mutual in MI) covers this kind of damage. Grand total to replace everything would have been around $2500 (mostly labor).

If the replacement harness doesn't fix things, I'll be sure to post any more news.

Thanks for all your earlier input.

 

I was using the car as a commuter daily...I never noticed. We had a problem with them getting into our house too, and they were mainly nocturnal.