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Worrying failure - Hybrid system malfunction

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Matt_O

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Discussion starter · #1 ·
Had an uncomfortable experience tonight.
In EV mode just north of 70mph in the outside lane of the motorway. I planned on going into HV mode as was going to accelerate up to 80 and beyond.
Switched to HV mode for a bit of power to clear the cars on the inside who had started to speed up.
There was a sudden judder and "Hybrid system malfunction Visit your dealer" came up, along with "pre collision system malfunction".
Car lost all power and slowed to a crawl. Throttle unresponsive.
I managed to get to inside lane - miracle no one rear ended me - it was dark and busy. Coasted into a lay-by -only just made it as absolutely no power in car.
Switched car off and restarted.
Amazingly it restarted as if nothing wrong - warning signs all disappeared. Both ICE and EV working normally.
Going to take it to dealer but beginning to lose confidence in this car - cars shouldn't just stop and lose all power.
Never had a conventional ICE die on me like that, and most diesel/petrol faults give you a bit of notice.
Felt I was lucky to avoid a more serious outcome. I'd rather the system protected me than the engine or whatever it felt it was doing.
 
#2 ·
Sorry to hear that. I am not 100% sure but there was a Prime XSE owner who needed a new ECU chip. Losing power during your drive is dangerous and requires immediate resolution. I hope you can run (no running below -10F) or bike (no biking below 20F) to work, which is what I would do if my Prime did that. My best guess is you may have a defective ECU.
 
#3 ·
So in EV mode at highway speeds (Owner’s Manual says to switch to HV mode for highway travel 3 times). You switch to HV push it past 80MPH before the Internal Combustion Engine (ICE) can warm up and contribute power (without a ton of bad emissions). The R4Prime has to switch to HV mode at +84MPH because the motor generators in the Synergy Drive are at max RPM at that speed. Sound like something overheated and shut you down. Should be some informative error codes in your R4P. Ask about the error codes in your vehicle and share them please.

Glad you were not hurt, and the R4Prime restarted OK.
 
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#4 ·
Chazz8 said:
So in EV mode at highway speeds (Owner’s Manual says to switch to HV mode for highway travel 3 times). You switch to HV push it past 80MPH before the Internal Combustion Engine (ICE) can warm up and contribute power (without a ton of bad emissions). The R4Prime has to switch to HV mode at +84MPH because the motor generators in the Synergy Drive are at max RPM at that speed. Sound like something overheated and shut you down. Should be some informative error codes in your R4P. Ask about the error codes in your vehicle and share them please.
Glad you were not hurt, and the R4Prime restarted OK.
Click to expand...
I hear you and your theory seems plausible. But losing power does not seem like a correct behavior or safe design if the reason is to protect the engine at the expense of driver/passenger safety. Are you talking about an instantaneous maximum RPM as a result of EV to HV switch? It is an interesting end case and something to note for myself. Are there other end cases: 1) Going up a 10% grade mountain pass at 60 MPH in an EV mode then having to switch to a HV mode before cresting it; 2) Accelerating in an EV mode then allowing the Prime to automatically switch over to a HV mode? If scenarios #1 or #2 is possible cause, then we should have seen more observations.
 
#5 ·
If the component that is overheating is critical to locomotion then shutting down seems right to me. Let see what the error codes say.
 
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Discussion starter · #6 ·
I’ve switched EV-HV in a similar way before without issue's. If it’s by design then the design is wrong - the system shouldn’t allow the situation in the first place rather than kill all power at 80mph! Will see what the dealer says.
 
#7 ·
Matt_O said:
I’ve switched EV-HV in a similar way before without issue's. If it’s by design then the design is wrong - the system shouldn’t allow the situation in the first place rather than kill all power at 80mph! Will see what the dealer says.
Click to expand...
The system shouldn’t allow the R4Prime shut down …. Unless it is it to prevent a more abrupt/damaging/violent shut down due to component operating outside of it’s safety parameters.

I’m guessing/betting MG2 or main Inverter/Converter will pop up in the error codes. What kind of odds can I get over there in UK.
 
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#8 ·
mine (not prime) hybrid stalled on a highway recently after pump recall swap. Mechanic was able to figure out in a minute it’s the low pressure pump based on codes.
dealer told me to to bring it when it happens again and made the repair after being pressured.

Read the codes and share please. Auto parts stores read them for free. A car mechanic will do it for 20$. They have more fancy scan tool. Don’t erase them .
this will give you an upper hand when you go to a dealer.
report the incidents on nhtsa.gov and/or British equivalent.
Last thing I would like to have is dangerous common issue not reported by customers.
 
#10 ·
I'm helping a lady friend buy a new car. To be frank I feel R4P is too complex, too potentially prone to weird issues exactly like this to recommend it to her, though I did let her know how nice it is to be in electric mode so she's coveting this now! Her commute is about 27m one way which means every day she will be toggling to HV mode while driving. I'm nudging her towards straight Rav4 or Highlander Hybrid which by now have to be ultra proven w/ lower potential for any and especially weird issues!
 
#11 ·
NoelinColorado said:
I'm helping a lady friend buy a new car. To be frank I feel R4P is too complex, too potentially prone to weird issues exactly like this to recommend it to her, though I did let her know how nice it is to be in electric mode so she's coveting this now! Her commute is about 27m one way which means every day she will be toggling to HV mode while driving. I'm nudging her towards straight Rav4 or Highlander Hybrid which by now have to be ultra proven w/ lower potential for any and especially weird issues!
Click to expand...
I would keep in mind that forums like these tend to be filled with people who have sought answers for problems they are experiencing. There is a selection bias on here and the RAV4 Prime subreddit of owners with issues. There are thousands of RAV4 Prime owners who will never go on the internet and say, "I have no problems with my RAV4 Prime."

That bearing in mind, I have no problems with my RAV4 Prime. What @Matt_O experienced is more likely than not isolated to their RAV4 Prime or a small percentage of RAV4 Primes. They mentioned a juddering before the warning lights. It sounds like the engine tried and failed to start, for whatever reason. That is worth investigating.

Regarding complexity of the R4P: I would argue that the Prime/Hybrid drive train is mechanically simpler than a traditional gasoline powertrain. The transmission is simple, there are no belts that can break, etc. HVAC is a behemoth and I dread the day something goes wrong with that.

A lot of people have an innate fear of electronic systems in their car and the likelihood of them failing; perhaps that's driven by more visibility into mechanical issues with increased number of sensors and information displays. The electronics likely aren't causing issues, but rather we are more aware of issues than we have been in decades past. If an engine experiences a fault but there were no sensors to tell you about it, did the fault really occur? (A play on the Tree In The Woods thought experiment.) The computers in this car aren't just going to decide, "Not today" at random. I lean towards agreeing with @Chazz8 that there is a larger mechanical issue, and that the computers are trying to avoid a more catastrophic failure.
 
#12 ·
iTim314 said:
I would keep in mind that forums like these tend to be filled with people who have sought answers for problems they are experiencing. There is a selection bias on here and the RAV4 Prime subreddit of owners with issues. There are thousands of RAV4 Prime owners who will never go on the internet and say, "I have no problems with my RAV4 Prime."...and that the computers are trying to avoid a more catastrophic failure.
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Those are some nice justifications for a really, and I mean, really bad issue as described in this thread. Am fully aware of selection bias in forums like this, thanks. That catastrophic failure can happen with this system and therefore the computers have to shut it down is hardly reassuring! In fact I'd much rather have this particular issue be failure of the computer or other sensing component than something built-in to the design that needs to be intervened in in order to prevent catastrophic failure. I guarantee you it would take some serious 'splaining' if our friend read the initial post in this thread to convince her all's well w/ R4P! That being said--there is zero question R4P is a far more complex system including its cooling system and drive train and certainly is far less road proven as for every R4P there are a 1000 Rav4 Hybrids on the road. Our friend is elderly and lives alone w/ no handy tech support person to explain things to her like I do w/ my wife and our R4P
 
Discussion starter · #13 ·
I'm not convinced there is what an end user would call a larger mechanical issue.
The car is driving just fine today in both hybrid and EV mode, and pulled away normally immediately after stopping and being restarted.
A serious mechanical issue as I would define it would be something that would reoccur on next use or immediately thereafter.
I think a sensor didn't like something an the answer was a shut down.

I get the engineering sentiment about problem prevention and mitigation but that shouldn't mean turning the car into a dead duck at 70mph on a busy carriageway.
Given that there was a full battery charge an "ICE unavailable - EV mode only" would have been a better engineered solution to protect the engine than sudden death (the car's power in this case , but could have been otherwise!). Having looked today in the daylight at the distance travelled before standstill I reckon it was 1/2 a mile - there must have been some sort of limp mode in action to clear that distance but it certainly wasn't long enough or powerful enough.
The beauty of a conventional engine is that by and large you normally hear something is amiss and it usually stays running until the ignition is turned off - irrespective of the mechanical consequences.
 
#14 ·
In my 20k miles post, although I mentioned that I never had an issue with the drivetrain, something like what you described happened to me really briefly as I was exiting the driveway of my work place. I was in EV mode, though, and from a stop sign, as I was pulling out, power just cut out and I started coasting for a second or two. I can't recall if there were any hybrid system malfunction errors. But, the system came back online quickly for me and I was able to drive. It was a bit freaky, but it resolved so quickly, I wasn't sure I was just imagining things.

To be fair, this kind of thing has happened to me before in ICE cars where the engine just stalled out and stopped. And, not that long ago, I found out that my 2009 Honda Civic has had major engine issues where small engine block cracks would form out of nowhere, and the engine would just up and die on people as they were driving on the hwy. No power. Hope you find some answers.
 
#15 · (Edited)
Matt_O said:
Going into the dealer on Thursday so I’ll post an update after.
Click to expand...
It will be very correct and very useful if the technicians after the diagnosis will inform you (and us) of the results of such checks.
1. Health Check Results*.
2. DTC(s) with status Current and History and its Freeze Frame Data.
3. Vehicle Control History data* of Hybrid Control System.
4. Vehicle Control History data of Electronically Controlled Brake System.
For example,
* https://alflash.com.ua/2021/rav4hv/health_check.png
** https://alflash.com.ua/2021/rav4hv/hyb_vch.png
 
#16 ·
Matt_O said:
I get the engineering sentiment about problem prevention and mitigation but that shouldn't mean turning the car into a dead duck at 70mph on a busy carriageway.
Given that there was a full battery charge an "ICE unavailable - EV mode only" would have been a better engineered solution to protect the engine than sudden death (the car's power in this case , but could have been otherwise!).
Click to expand...
You would have been t-boned if your car had stalled while making a right turn (left turn for us Americans) with oncoming traffic. Not an engineer but I would have given the driver some chance (i.e., 30 seconds) to maneuver out of it before cutting the power off. I hope the driver and passengers are considered part of the essential safety parameter. I would be nervous to make left turns (or rights turns for Brits) with your RAV4.
 
Discussion starter · #17 ·
OK, so a bit of an update.
Still in dealer as they are back and forth to Toyota technical - fault code (won't tell me over phone what it was) indicates either transmission or engine - so not really narrowing it down much!
Not something they have seen before.
They say car not safe to drive (even though it had seemed fine)
Likely to be a couple of days.
Will reveal more in due course...... meanwhile I will enjoy the delights of the Aygo courtesy car which art least has better DAB radio reception than the RAV 3x its price!
 
#18 ·
Matt_O said:
fault code […] indicates either transmission or engine - so not really narrowing it down much!
Not something they have seen before.
They say car not safe to drive (even though it had seemed fine)
Click to expand...
Given your description of the events, this doesn't surprise me. The engine failed to start for whatever reason.

Keep us updated if/when they find the problem.
 
#20 ·
Matt_O said:
OK, so a bit of an update.
Still in dealer as they are back and forth to Toyota technical - fault code (won't tell me over phone what it was) indicates either transmission or engine - so not really narrowing it down much!
Not something they have seen before.
They say car not safe to drive (even though it had seemed fine)
Likely to be a couple of days.
Will reveal more in due course...... meanwhile I will enjoy the delights of the Aygo courtesy car which art least has better DAB radio reception than the RAV 3x its price!
Click to expand...
Great car. Wife had one from new for about 6 or 7 years. For city driving at least. Very economical.

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