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Discussion Starter #1
My 2016 Volt died today just as I approached my house, I was driving on ICE and it just locked up and froze. It felt like the parking brake was engaging, it wasn't. I was able to turn the vechicle on/off and barely limp it into my driveway. At least my Volt knows where to breakdown, zero fault for 4 years ... until today.

Only 2 DTC fault codes show.

P0AC4 HC ECU MIL ON Request
P07A3: Transmission Clutch 1 Stuck On (Freeze Frame)

Anyone have any experience with this code, the MIL will not reset (hood lifted) or in normal mode.
Engine runs fine, I can shift the car into gear but nothing happens, it just sits there, ELEC mode or ICE mode.
When I turn off the car, I hear several clicks on the right side of the engine.

Anyone have any experience with this fault?
 

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Discussion Starter #2
Today I went out and pushed the car back and forth, it moves about a foot or so in either direction before it grabs. I started the vehicle and drove backwards and forward on my driveway. There are 2 sticking points over a 5 foot distance than it moves freely for about 10 feet where the process repeats itself ... same in drive or reverse. This is exactly what I felt when I drove it the final 100 yards to my driveway last night.

The shifter moves freely, shift indicator reads correctly, but the car is not entering a proper park mode. Yet the shifter must be in Park to start the car. I tried to digest the following link to get a better understanding of how the transmission works.

This monkey motion is a bit over my head but I did find this.

Clutches:

1) Clutch 1; Acts as brake to lock ring gear to housing or allow it to rotate
2) Clutch 2; Connects/disconnects MGA to/from the inner shaft
3) Clutch 3; Connects/disconnects IS to/from the ICE
4) Clutch 4; Connects/disconnects the inner shaft to/from the outer shaft
5) Clutch 5; Dog clutch, Connects/disconnects MGA to ring gear

P07A3 DTC states that Clutch 1 is Stuck On.

Clutch 1 acts as a brake, yes that is what I experienced, it felt like a brake being applied. Is Clutch 1 nothing more than the transmissions parking brake ... or is there more to it.? Perhaps the paddle brake on the steering wheel is also tied to Clutch 1.

I suspect an external sensor is causing the problem, maybe the shifter mechanism or perhaps the paddle brake. If there was an internal transmission problem you would think there would be a lot more DTC's logged. I was starting to experience the shift to park indication issue over the past month but a quick flick of the shifter button took care of that issue.

I recently moved to Kona, Hi and the only GM dealer on the island is 90 miles away in Hilo.
This appears to be a tiny GM dealership and I have my doubts that they have a qualified Volt technician.

Stuck between a rock and a hard place.
 

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Discussion Starter #3
So I decided to pull the negative post off the 12V battery overnight. Clamped it down this morning, no CEL, drove the car down the block ... then the dreaded Shift to Park message and the car came to a stuttering stop. Won't shift into gear, dead in the road.

P1AEE is the only fault. (P07A3 no longer in view)
 

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Discussion Starter #4
Had to push the car back into the driveway as moving the shifter does absolutely nothing now.
I've decided to grab the bull by the horns and change out the Shifter Assembly myself.
The logic is that the shifter mechanism needs to be changed anyway, if it fixes the problem it saves me an expensive 90 mile tow job, the hassle of negotiating with a new dealer, and the satisfaction of fixing a major issue myself.

Looks pretty straight forward per this You Tube. (Thanks Justin87)

Newest Shifter Part #13534319 $60

I will report back with results.
 

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Discussion Starter #5
I was able to replace the Shifter Assembly in less than 1 hour with the assistance of the above video.

Unfortunately the P1AEE message remains and will not reset. I was able to put the car in gear and move it around in the driveway. Same jerking & stuttering, then the vehicle stops and says "Shift to Park". Dead, no forward, no backwards, no park. Gearshift indication is normal on the screen but the shifter does nothing.

Just read this current thread and now I fear the worst.

I find it strange how there were absolutely no indications of this impending doom and it only threw 2 DTC's.
Perhaps if the transaxle fails while going faster all kinds of bad things happen, in my case I was only going 10 MPH.
I'm still holding out hope that it's just a module or sensor ... but I am preparing myself for a very long repair.

Time to bite the bullet and get my Volt towed to the dealer. :cry:
 

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Discussion Starter #6
I upgraded my Scan Tool to read all the GM enhanced diagnostics codes. This is what I found.

171319
 

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Discussion Starter #7
Just wonderful, my 2016 is just outside of the 5 year Drivetrain Warranty. Purchased Oct 2015

Per PIC 6244D the drive unit (transmission) requires replacement.


Preliminary Information
PIC6244D Diagnostic Aid For Vehicles All DTCs P1AEE P1AEF P1AF0 P1AF2 P1E22
Product Investigation Review Required Models
Bulletin No.: PIC6244D Published date: 07/9/2019
Brand: Model: Model Years:
VIN:
Engine: Transmissions:
from
Chevrolet Chevrolet Buick
Volt Malibu LaCrosse
2016 - 2019 2016 - 2019 2016 - 2018
to
All All All
All All All All All LKN
5ET50 (MKV) 5ET50 (MKE) 5ET50 (MKV)
Involved Region or Country
Condition
North America, Korea, China
Some customers may experience DTCs P1AEE, P1AEF, P1AF0, P1AF2, P1E22.
Cause
If all five DTCs are present, then there is an internal concern with the drive unit (transmission).
Important: If only two or three of these DTCs are present, then proceed with normal SI diagnostics as the concern may not be internal to the drive unit.
Correction:
The drive unit (transmission) will need to be replaced.
Version History
Version 5
Modied
01/09/2017 - Created
10/17/2017 - Updated to add 2018 model Year
9/17/2018 - Updated to add 2019 model year.
10/08/2018 - To Remove Shifter to park message
7/9/2019 - Removed Reference to other Service Documents
© 2019 General Motors. All Rights Reserved.
 

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Bill Allen,

There may be no need to panic, I had the same issue and it was the 5ET50 failure that produced all of the codes that you listed. Mine was replaced for free with a loaner car for no cost. I think your warranty covers your electric car transaxle, read below:

ELECTRIC HYBRID WARRANTY
For vehicles sold in the United States, in addition to the Bumper-to-Bumper Coverage described previously, Chevrolet will warrant certain components for Each Chevrolet Volt, and Bolt EV, and Malibu Hybrid for 8 years or 100,000 miles (160,000 kilometers), whichever comes first, from the original in-service date of the vehicle, against warrantable repairs to the specific electric propulsion components of the vehicle.

Stephen
 

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Discussion Starter #9
Thanks Stevon, I already linked your thread "Shift to Park Dead Volt" above. While I enjoyed the spirited conversation about the operation of the 5ET50 transaxle, I was most concerned with the internal pictures you provided, can you post a link where you found them. I'm an aircraft mechanic by trade which makes me very curious about what breaks inside these transaxle's to create such a catastrophic failure.

Fact is when an over voltage is detected by either Hybrid Powertrain Control Module, within seconds, it commands the car to shut off and engage Solenoid 1 which brakes the car to an immediate stop. Just like the Boeing 737 Max, this is some piss poor software engineering and could potentially be very dangerous in certain driving conditions. Just like the Max not nearly enough 'and/or gates' (digital logic) were written to compensate for real life driving conditions. Shut the motors off fine ... but don't instantly engage the parking clutch at the same time you loose power steering and power brakes. I suspect the software engineers where most concerned about saving the transaxle motors and the main battery from severe damage. A simple wheel speed indicator logic would allow you to coast to a stop without the aggressive braking by clutch 1.

With the car in my driveway and full access to all 30 Volt's computer modules provided by Auto Enginuity's advanced software I am able to save the freeze frames, erase the faults, run tests, and re-create them at will. While I can erase the PO7A3 Clutch 1 message and get the car to move, Clutch 1 remains engaged and the jerking feel is the electric motor overriding the parking clutch. 2 override events of Clutch 1 and the vehicle shuts off, "Shift to Park" message appears, and logs all those DTC fault codes in the Hybrid Powertrain Control Modules.

While this was a nice exercise in what actually happens when an over voltage containment failure occurs inside the 5ET50 transaxle ... it sure doesn't inspire any confidence in the mechanical design or software.
 
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