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2015 Volt - Propulsion Power Reduced

47K views 45 replies 31 participants last post by  JGWEIR 
#1 ·
I've owned my 2015 Volt for a little less than three weeks and have 400 miles on the odometer. I've been reading with interest about other peoples issues with the Propulsion Power Reduced warning, but I'm not sure what I've experienced is the same thing.

During the first few days of owning my Volt, I was driving down a flat road in town doing about 45 mph when the accelerator suddenly didn't respond. The car began to slow down despite me pressing down on the accelerator. There was thankfully a red light a block ahead and I more or less coasted to the light. While stopped, I frantically checked everything, thinking I had accidentally hit a button or switch. Nothing looked out of the ordinary, and I don't remember seeing the Propulsion Power Reduced light at the time. I also don't remember how much range I had left (if any) in electric mode. When the light turned green, I stepped on the gas and the car resumed its normal functionality and was fine. I assumed I had mistakenly pushed something I shouldn't have and quickly forgot the incident.

Several days later, I was driving the car on the freeway. I had about 30 miles of range on the charge and my destination was about 26 miles away, meaning that my return trip would be made mostly using gas. Fine - that is why I purchased this car instead of an all-electric. On my return trip, I made it most of the way home in stop and go traffic when the traffic started to lighten up. I stepped on the accelerator to maintain the speed of traffic and nothing happened. I floored it, and there was little to no response. I was losing speed in the fast lane and there was nothing I could do about it. I looked at the dash and saw a light that stated Propulsion Power Reduced (no kidding - I couldn't drive the car). The car was losing speed and didn't respond to anything my foot was doing on the accelerator pedal. I put the hazard lights on and came to a stop (again - this was in the fast lane of the 405 freeway in Los Angeles). I turned the car off while all around me cars honked and people flipped me off. When I turned the car back on after a moment or two, the warning was gone and the car reacted as it should. I had my wife call the dealership and I immediately drove there.

The service department rep told me that the Propulsion Power Reduced warning can come on when climbing steep hills. I told him that I was on flat roads both times the car failed to accelerate and he seemed surprised by this. It was late on a Thursday, and I was leaving for a week long trip the following evening. The serviceman told me he'd try to get it to me before I left the following day, but was not able to. I didn't hear back until this past Friday (the car had been in the shop just over a week), and the message I got was that there was nothing wrong with my car and to come pick it up. I am now back in town and just got off the phone with the service department. They assured me that while my car twice refused to accelerate on flat roads (one a residential street, one a busy freeway) that nothing was wrong with it. I've only had the car in my possession for eight days (it has been in the shop for longer) and what has happened isn't safe. If I'd had any idea this was a possibility, I never would have purchased this car.

I would be very interested to hear if anyone else has experienced anything like this and if so what the outcome was. I've been told that the car has performed as it should, yet I've never owned a car that didn't go forward when you stepped on the gas. Again, the car is a brand new 2015 Volt with only 400 miles driven in 8 days of being at my house. I'm concerned and want to know if this is a problem specific to only my car, or if this is something that has happened to others, and if so, was there a solution. Thank you in advance for any help or assistance.

Brooks
 
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#2 · (Edited)
When this happened did you press the OnStar button and have them read you the error codes (if any). Posting the error codes here can help diagnose an issue.

Could you have been out of gas?
 
#4 ·
From the OM:
The vehicle may be driven at a reduced speed while this message is on, but maximum acceleration and speed may be reduced.
Did you climb a hill before you were driving on the flat road and this occurred?
 
#5 ·
Only time I've had PPR was when my engine stalled. It should behave like normal, just the accelerator pedal will feel loose and accel will feel weaker than normal.
In short it should just drive like a Prius :p

As above, you should have had access to half the normal power rate, or 55kW

Something definitely is wrong there. Get a volt advisor involved.
 
#6 ·
I routinely travel a 7 mile 6% grade in CD mode and I have never seen a reduced propulsion power warning. There are no hills worthy of the name in So. Cal. (lived in Newport Beach for three years). As recommended above get a volt advisor involved. There is definitely something wrong with the car. Stopping anywhere on the 405 is scary let alone the left lane.
 
#15 ·
There are no hills worthy of the name in So. Cal. (lived in Newport Beach for three years).
Really? I tried climbing Angeles Crest Highway with no battery - no can do, at least not at the speeds I want to drive. Had to turn around and go back down (was going to Newc's for breakfast).
 
#7 ·
Hi,

Sorry that your Volt has an intermittent problem, because it's such a great car. But like any car, you can have a glitch. I had one with my intermittent door lock on my 2014 Volt. Search for "pierreforget" in the forum and you will see the solution for an annoying problem. But I must admit that loosing power on the freeway is critical. As I was a mechanic in another life, I know that any car can get that. I remember a Pontiac 1969 who had that. Motor would stop suddenly, stopped the car, restart the motor and everything thing came back to normal for a while. Dealer couldn't figure it out, so we found the problem. There was a filter inside the gas tank who would get kinked once in a while and stopped the flow of gas.

As suggested above, if it happens again, make sure you call Onstar and get a Volt advisor involved. One of my relative is a trained Volt mechanic at a dealer and he told me there is really no problem with Volt in general. But there is exceptions to any rule.

And remember, from my repairing experience, the more difficult the problem appears, the more simple is the solution. Meaning here, don't search for a complicated problem, search for a simple stupid thing...

Only thing that annoys me with the Volt is there is no warning when you are missing windshield washer liquid. Quite annoying on the autoroute at night when wet snow is coming down. Didn't find it funny... They shoud have this feature on a car of this price. But now that I know, I keep it full all the time.
 
#10 ·
Thank you for all of the great posts. I will try and answer the questions from the forum as best as I can.

*I didn't think to push the Onstar button as the car is brand new and I didn't remember it was there. I also wasn't thinking of that when it wouldn't move forward in the fast lane. I'll keep it in mind the next time it happens (finger's crossed it doesn't)

*The car was not out of gas. It had at least a half tank.

*The check engine light did not come on - only the PPR (I don't recall if the PPR came on the first time the car failed to accelerate).

*I did not drive up a hill prior to the failure of the car to accelerate normally. After I restarted the car on the freeway, I drove it on the flat for another five miles before going over the mile or two "pass" between the San Fernando Valley and the Santa Clarita Valley with no issues, other than my rattled nerves.

I just picked up the car from the service department of the Chevy dealer I purchased it from and was told the car had a clean bill of health and that there was "nothing wrong with the car". The technician who looked at my car was at lunch and I am expecting a call from him for more information, but they told me expressly that they found nothing.

Along those lines, I am new to this forum as of today, and I don't know anything about the Volt Advisors. I apologize in advance for my ignorance, but any help is certainly appreciated. Thanks again for the assistance, and I will certainly share more when I know more. I just wanted to make sure that this wasn't a common issue before I decided to push the dealer's service department a little harder.
 
#34 ·
Brooks,

You came to the right place. The depth of domain knowledge here is staggering. Everyone is here to help and we will all need to share in someone's experience at some point.
 
#11 ·
Regarding your first loss of power, were you driving in L and trying to shift back into D? It’s easy to push the stick past D and end up in N, at which point you no longer have power, stepping on the accelerator does nothing, etc. Electric cars don’t embarrass you by loudly revving the engine instead of giving you more power, so we don’t get that audio clue to know we’re no longer in gear. When you came to a stop at the light, you tried a lot of things, including moving the shifter, which corrected the problem.

OR... perhaps you tried switching driving modes, say, from Normal to Sport, put your finger on the On/Off button instead of the Mode button, punched it twice, and then didn’t notice the message that appears far too briefly telling you how to prevent the car from turning off, and so it did turn off, and then you stopped and restarted it.

For the second instance, you were headed home using the ICE after depleting the battery. It is possible there’s a glitch that needs attention in that system (as evidenced by the unusual performance after the Reduced Propulsion mode message appeared - usually the car is just a bit sluggish, not unresponsive - that then disappeared after stopping and restarting the car). Your attempt to speed up as the traffic cleared might have triggered the Reduced Propulsion reaction, putting additional load on something that needs adjusting or fixing or a fluid reservoir that needs filling.

Another possibility... The traffic cleared, you punched the accelerator to speed up, and the Reduced Power notice appeared. Perhaps you were running low on gas (I see now you just said you had plenty), the car knew your battery was depleted, and you had just put additional demand on the generator output by speeding up, so the car went into Reduced Propulsion mode as a precautionary move to let the driver know of the rapidly diminishing remaining driving range.

As others have mentioned, OnStar can tell you of any error codes generated by these incidents, which would help diagnose what happened.
 
#12 ·
Your post is very puzzling. And it's definitely NOT how a typical Volt drives. Something is wrong here. Write your VIN# on a paper so you can have it handy... Call a Volt advisor (877) 486-5846. Start by saying you are disappointed. Then describe the issues. Hopefully they can help you get a resolution. (Which sometimes involves taking the car to a different dealership than you are currently working with...)

I sincerely hope it gets resolved soon. This is NOT how a Volt drives. Sorry for the bad & scary experience.
 
#13 ·
Thank you to everyone who wrote in. In talking with the technician who saw my car at the dealership, he told me that he ran it through the computer and nothing came up. He talked to Chevy and they told him to charge the Volt, drive it and see if it happened again, which it didn't. He then called them back and they told him to release the car to me as there was nothing wrong with it. He suggested that I put the car in sport mode and see if the problem repeats itself in the next few days (the car has always been in normal mode).

I then took the advice here about calling On Star. They ran a 30 second diagnostic and also didn't find anything.

I will absolutely give a Volt adviser a call and see if I have any luck. It doesn't seem like this is the norm (not that I would expect it to be) and it feels pretty awful to have a brand new car that I don't trust.

Thanks again for all of the help, and I will report back when I learn more.
 
#14 ·
The Volt adviser I talked to suggested that in looking through the notes on the car, the dealer didn't do everything in the 8 days the car was in the shop that they might have done. He gave me the option of driving the car and waiting to see if the issue would happen again, or taking the car back to the shop and having him send them an email stressing what should happen next to resolve the issue. Since I don't feel confident or safe driving the car with my family in it, I took the car into the shop. I am interested to see what happens next, but am grateful for the outpouring of suggestions and support I have received here. Thanks to everyone who took the time to respond and offer suggestions and help. I really appreciate it.
 
#16 · (Edited)
For a bit of perspective on how normal PPR events work: I experienced a real PPR event only once in almost 50K miles. It was after the battery was dead, running in Normal mode, climbing serious mountain passes in Montana, and holding 80 MPH. PPR mode kicked in only after about 2 minutes of hard climbing while the engine was screaming to keep up with the demand. When it happened, the car noticeably lost power and slowed to about 65 MPH for the remainder of the climb and then the engine continued screaming for about 3 minutes while I was going down the other side of the mountain. That extra 3 minutes of high engine output was replenishing the buffer power that the car normally doesn't want you to use.

The whole reason for PPR in the first place is to prevent you from draining the battery so low that it causes physical damage to the cells. The management computers in your car consider the battery "dead" when it actually has quite a bit of charge remaining. I think the number is around 20 to 25 percent, but I'm too lazy to go look it up right now. Assuming 20% is correct, the car will fire up the engine and use whatever throttle setting is needed to keep the battery within a narrow window of charge very close to 20%. If you stomp the accelerator for a moment to pass someone, the battery might dip down to 19% for a moment until the engine winds up and recharges the battery to 20% again. Step on the brake, the regeneration might bring it up to 21% and the engine turns off. Go tearing up a steep mountain where you need 90 KW of propulsion, and the 55 KW generator isn't going to be able to keep up which results in the battery dropping to 18, 17, 16, etc... At some point, the computer decides you're not allowed to pull any more out of the battery and reduces propulsion output to 55 KW in order to prevent any further drain from the battery.

From the sound of the original post, I don't think a legit PPR event is what happened. I don't know what did happen, but I doubt it was a legit PPR. Something else is going on and the dealer just hasn't found it yet. It's possible the accelerator sending unit is faulty and simply didn't sent a "go faster" signal to the computer for a moment. It's equally possible that there was an internal glitch in the high voltage inverter. One of the more common "gotcha" problems for new owners is playing with the drive mode button and accidentally pushing the power button twice instead. That instantly shuts down the propulsion system and has left more than one person cussing on the side of the road. Not saying that's what happened, but it's worth mentioning since it's happened before. If you do happen to have that happen, just shift to neutral while coasting, do NOT step on the brake, and press the power button again. Power comes right back on and you can shift to Drive and continue driving.

The problem with forum diagnosis is that we can't poke and prod to find out what's really going on. Your dealer is the only one set up to do that, and it sounds like they did an incomplete job of it. Hopefully the Volt Advisor can help guide them through a correct fix and give you back your new car smile.
 
#20 ·
As I mentioned yesterday, at the suggestion of a Volt adviser, I took my Volt back to the dealer. I wrote an email to the dealership service manager who wasn't there that day (also CC-ing the General Manager of the dealership) detailing my concerns and why I didn't think there was "nothing wrong with my car". I got a concerned call back within a couple of hours stating how he agreed with me that more needed to be done and that he was personally going to take matters directly to GM on my behalf. I'm not sure what that means, but I'm grateful that something is being done with the car other than giving it back to me with "nothing wrong" and hoping for the best. Thanks to all who took the time to respond and help. It gave me valuable information with which to move forward and work towards correcting the problem. I'll write back when I have a definitive answer as to what caused the issue. Thanks again!

Brooks
 
#21 ·
So far, the dealer has found nothing wrong with my Volt. Tomorrow will be the 15th day the dealership has had my car in their possession, and I've had it to drive only 9. There was a several hour window between me picking the car up from the dealer's service shop the first time and me learning more about how unique my situation was while reading this thread...which led to me calling a Volt adviser that I learned about on this very forum...which led to me returning the Volt to the dealer because nothing had been fixed and the underlying, potentially large safety issue was still out there looming. The service manager drove my car home last night and is doing the same tonight, hoping to replicate the accelerator pedal not doing anything when pushed and the car losing speed. He and his crew have put about 150 miles on the car since having it in the shop (I've only put 430 on it), but I'm wondering what happens if they can't get the car to duplicate the issue, as it (only (?)) happened to me twice in 400+ miles.

If they try and give me the car back without finding anything, what should I do? The car has done it to me twice in only a few days of owning it and I really don't think it is safe to drive a car that might not accelerate at the needed moment - especially on the frequently difficult and jammed roads and freeways of Southern California. Do I have any recourse and is there another level of service that I can take this to? I really like the car (when it is able to move forward) and I don't want to even think about getting rid of it, but I also need a car that I can feel safe driving my family around in.

Secondly, just to confirm what several people have said in this thread and others, when you have had the PPR light come on, does your Volt lose the ability to accelerate? Does it lose speed? Can it still maintain the speed of traffic? From what I've heard, my Volt should not be doing this when it has (flat roads/freeways), but I'm wondering if it losing speed and the ability to accelerate is normal when the PPR light comes on, or if a typical Volt behaves differently.

I'm trying to determine what needs to happen going forward and at the same time anticipate what the dealer might do - both for my benefit and for theirs. Thank you in advance for any and all answers...I really appreciate all of the time the community has spent trying to help me with my dilemma.

Brooks
 
#23 ·
#22 ·
Have you seen this......



2013 Chevrolet Volt Power Train Service Bulletin 341563

NHTSA: Action Number: 10047659 Service Bulletin Number: 341563
Report Date:
Oct 01, 2012Component:
Power Train
Summary: Chevrolet: due to software anomaly, hybrid powertrain control module (hpcm2)may open and reset propulsion power relays, and electric motor may temporarily stop, because of incorrect date information. Model 2013 volt. *pe
 
#24 · (Edited)
Question for the OP. How many times had this battery been fully discharged (to the point of extended range and engine run) and then recharged?
I suspect very little if any complete discharge-charge "cycles" have occurred which can have an impact on some of the algorithms used to calculate SOC and available peak power. That is the only time I have encountered such an anomaly and after completing 5-10 discharge-charge cycles there is never any reoccurrence of the indicated error.

Anytime the battery management system observes that the available peak power from the RESS is less than 35kW and the current demand may be exceeding that threshold the "Propulsion Power is Reduced" message will appear and the available power from the battery controlled in a fashion to prevent exceeding it's available headroom. (reduced power) This can occur normally under certain conditions most typically under high load such as climbing a steep grade, but can also occur if the battery cells are extremely cold (<5F/-15C). The message can also appear when certain DTCs have been triggered to control power levels as a fail-safe measure.

Under the condition the OP has described (and assuming no DTCs) there should never be such a message displayed.
So that leaves me to believe something may have gone wrong with the process of calculating the available power which is a function of the algorithmic estimations of SOC and active pack voltage and current measurements.
If there was something actually wrong with a particular piece of hardware that is involved in this process (eg. current sensor, voltage sensor/s etc) then the issue is sure to manifest at some point in a single discharge cycle and will be repeatable by the dealer technician. (and usually DTCs set)

But in short I have seen a few of these types of anomalies crop up on Volts that have sat on a dealer lot for an extended period of time, (usually with a dead 12V battery) then sold to a customer BUT then isn't initially charged and discharged to full depletion a few times in order to establish certain statistical base-lines in the software. If the car is driven for just short trips and then the charge simply "topped up" it can at times create some conditions that can cause this odd behavior. (as well as a few others like fuel used indications when the ICE hasn't run)
So barring some sort of actual battery cell/pack issue I suspect after a few complete discharge-charge cycles the issue will likely never be seen again.

HTH
WopOnTour
 
#25 ·
Thanks again for all of the information. I'm not sure the status (# of full charge/discharge cycles, the current charge level or fuel level) of the Volt when it first refused to accelerate, but the second time it happened it was 1/2 way through its second tank of gas and had done several full cycles of charge/discharge. The car had gone through its electric range and was driving on gas alone (and had been for about 10 miles before the incident). Thanks again for the continued help, and I'll pass along information as I have it.

Brooks
 
#26 ·
Ahhh well that changes things a bit. From your initial description I had somehow assumed you were driving electrically, but you were in fact in extended range (CS) mode.
In CS an observed issue with ICE operation can also bring up this message. BUT typically there should have been DTCs as well. However depending on the fault it quite possibly might have been a Type-B DTC that only trips fully (and turning on the MIL/CEL) after 2 consecutive trips with failure. (sometimes called an "armed" DTC)
So a DTC may have been present as a "history DTC" and the dealership may have quickly discounted it.

The dealer tech can actually go back onto the PC originally used to check for DTCs in the car and retrieve the initial DTC scan results as GDS2 records that data for future reference. ( a handy feature not often used)

I suspect there actually was a DTC set, but without any driver indication such as the CEL. Knowing that DTC would help to establish what fault the ECM may have detected with the ICE.

WOT
 
#28 ·
With all the computer systems one would think this incident would have triggered a Code somewhere in the system. I would
not have my wife drive any car, espicially a 2015 model year vehicle, with this problem not fixed. I would start contacting supervisors of supervisors to the top of GM's head person. This is unacceptable.
 
#30 ·
#29 ·
I know this belongs in suggestions, but the present issue makes the case.

There are holster monitors you can wear for your heart, your blood sugar, your sleep respiration, even your brain waves.

Solid state storage with amazing capacity is now really inexpensive.

GM should come up with a piece of test equipment that sits on the CAN port and records everything until a problem recurs and the driver or dealer stops the recording. The data would be transmitted back to the factory offline. I expect the GM already has analysis software for the CAN data stream.

In the end, DTC codes are programmed actions because some engineer thought something might happen. No one can think of everything.
 
#31 ·
Day 19 that the car has been in the shop (I've only had the car to drive for 8 or 9 days) and I heard yesterday that an engineer from GM was coming down to my dealership to look at the car. He was supposed to arrive yesterday or today but unfortunately didn't. As I started typing this update, I received a call from the dealership to say that the engineer from GM ran into a problem and wouldn't be able to examine the car until Thursday, which will be day 21 that the car is in the shop. I'll write more when I've heard something worth updating. Thanks again for the continued support.

Brooks
 
#32 ·
Obiwan - I saw your post that stated that you have encountered a similar situation with your Volt. Did it happen only once, and under what conditions? Was the dealer able to find the issue and if so, what was it? Very scary. I'm sorry you also had to go through this and I'm hoping Chevrolet was able to fix your Volt so that it the problem hasn't recurred. All the best, and thank you for your post.

Brooks
 
#33 ·
I just heard back from the dealer. The GM technician looked at my Volt yesterday and the service person I talked to told me that they were ordering a new transmission control module to put into the car. The part should arrive on Monday and I should get the car back on either Monday or Tuesday. I'm not mechanically inclined (an understatement), but am wondering if that malfunctioning part could be what caused my Volt to twice (under difference circumstances) stop accelerating and in at least one of the cases, trip the Propulsion Power Reduced light on the dash. I'm a bit wary of my dealership's service department after they sent me on my way the first time saying there was nothing wrong with the car, and I want to make sure this will (hopefully) make my car safe to drive, and not simply be a way of them getting me out of their hair. Thank you in advance for any insight or advice.

Brooks
 
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