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2016 Volt, produced October 2015, about 500 miles on engine, 17,600 total, car died. At dealer for 10 days total, Transmission replaced. Back to normal. Here are the 16 codes that were thrown and you probably don't want to ever see all at once:

p0ac4
p1af0
p1af2
p1bob
p1b43
p1e1e
p1e22
p0a46
p0c04
p1aee
p1aef
p1af4
p1af6
p1e1c
p215c
p3260
u0078
 

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Thanks for reporting the codes...Was the service at the dealership a pleasant experience?
 

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Thank goodness for the warranty. Wonder if this repair would fall under the 8/yr (10/yr if in California) powertrain warranty.

That is an intimidating set of codes.
 

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Thank goodness for the warranty. Wonder if this repair would fall under the 8/yr (10/yr if in California) powertrain warranty.
Although I can't say I remember this comment perfectly well, I thought the guy at the dealership who did all my paperwork told me it was an 8 year warranty on the power train, and I'm in CA.
 

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Discussion Starter · #5 ·
Thanks for reporting the codes...Was the service at the dealership a pleasant experience?
Yes because I know the Volt tech for the past 6 years, he's been working on both my Volts since 2011. They give loaner cars and 10 days total time was less than some of the other transmission replacements people dealt with elsewhere.
 

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There is a recent bulletin PIC6244 related to "Shift To Park Message" AND DTCs P1AEE P1AEF P1AF0 P1AF2 P1E22 present
Depending on the result of tests, and the combination of DTCs this diagnosis MAY result in the replacement of the entire transaxle on 2016-17 Volts

http://sandyblogs.com/techlink/?p=7226

DTCs P1E1E (not pieie) or P1E22 (not pie22) set alone, would have likely played into simply replacing the Transmission Control Module (TCM) only, others on their own possibly the replacement of the power inverter module inside the transaxle

So a lot of variables as to the final correction necessary for similar issues

HTH
WopOnTour
 

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Who thinks I should go fish up that repair manual I found and translate all these DTCs into brief layman's terms? :p
 
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Nevermind, I got bored and did it anyways.

P0AC4 - Requested MIL illumination (generic code)
P1AF0 - Drive Motor A Fault/Isolation lost between mid-pack voltage and chassis
Essentially, part of the battery got shorted to the chassis through Drive Motor A
P1AF2 - Drive Motor B Fault/Isolation lost between mid-pack voltage and chassis
Same as above but through Drive Motor B
P1B0B - Drive Motor A Low Voltage/Mid-pack voltage low
Battery voltage in one segment lower than expected (probably because it was shorted to ground...)
P1B43 - Drive Motor B Low Voltage/Mid-pack voltage low
Same as above, measured at Drive Motor B
P1E1E - Auxiliary transmission fluid pump voltage low
Same as above, measured at transmission fluid pump
P1E22 - Auxiliary transmission fluid pump fault
Same as P1AF0/2, shorted through transmission fluid pump
P0A46 - Drive Motor B position sensor degraded performance
MG (motor generator) B position sensor reported a strange/unexpected signal
P0C04 - Drive Motor B overcurrent
There was more than 600A of current through one of the three phases of MGB
P1AEE - Drive Motor A voltage high
Voltage measured at MGA was higher than 450V
P1AEF - Drive Motor B voltage high
Same as above, measured at MGB
P1AF4 - Drive Motor A Low Voltage/Mid-pack voltage low
Same as P1B0B, but measured at a different part of the battery
P1AF6 - Drive Motor B Low Voltage/Mid-pack voltage low
Same as above, MGB
P1E1C - Auxiliary transmission fluid pump voltage low
Same as P1E1E, but measured at a different part of the battery
P215C - Output shaft speed sensor correlation off
This one's worded a bit tricky, but it sounds like the output shaft speed sensor was reporting a different value than it should have been, given the speed of the wheels and individual motors.
P3260 - Internal Control Module Drive Motor Control Performance (say that 5 times fast)
Excessive motor torque and/or engine speed detected after driver shifts to Neutral.
(Shifting to Neutral is purely a digital operation, and the computer should instantly kill all motor torque and return the engine to idle)
U0078 - Doesn't exist in manual, but other U00** codes indicate "Bus communication off"
One of the modules stopped communicating with the main communication system, which is generally very very bad and indicates a serious problem.
So, the general gist of things is that "sh1t's broke, son". I'm no Volt engineer, or even automotive engineer, but given my hobbyist electrical engineering background, it sounds like there was at least one short circuit in the high-voltage system near the transmission essentially causing current to run from the battery through all the motors straight back into the battery. I'm not entirely sure how that happened; if the vehicle was in good shape and hadn't undergone any strenuous or shocking situations, it sounds like a manufacturing defect.

I just noticed that MGB was reporting the unexpected position sensor value as well as the overcurrent condition, but neither MGA or the pump motor were. That makes me think there was a short circuit in MGB (the main drive motor, i.e. the one not connected to the engine).
 

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Nevermind, I got bored and did it anyways.

P0AC4 - Requested MIL illumination (generic code)
P1AF0 - Drive Motor A Fault/Isolation lost between mid-pack voltage and chassis

P1AF2 - Drive Motor B Fault/Isolation lost between mid-pack voltage and chassis

P1B0B - Drive Motor A Low Voltage/Mid-pack voltage low

P1B43 - Drive Motor B Low Voltage/Mid-pack voltage low

P1E1E - Auxiliary transmission fluid pump voltage low

P1E22 - Auxiliary transmission fluid pump fault

P0A46 - Drive Motor B position sensor degraded performance

P0C04 - Drive Motor B overcurrent

P1AEE - Drive Motor A voltage high

P1AEF - Drive Motor B voltage high

P1AF4 - Drive Motor A Low Voltage/Mid-pack voltage low

P1AF6 - Drive Motor B Low Voltage/Mid-pack voltage low

P1E1C - Auxiliary transmission fluid pump voltage low

P215C - Output shaft speed sensor correlation off

P3260 - Internal Control Module Drive Motor Control Performance (say that 5 times fast)

U0078 - Doesn't exist in manual, but other U00** codes indicate "Bus communication off"


So, the general gist of things is that "sh1t's broke, son". I'm no Volt engineer, or even automotive engineer, but given my hobbyist electrical engineering background, it sounds like there was at least one short circuit in the high-voltage system near the transmission essentially causing current to run from the battery through all the motors straight back into the battery. I'm not entirely sure how that happened; if the vehicle was in good shape and hadn't undergone any strenuous or shocking situations, it sounds like a manufacturing defect.

I just noticed that MGB was reporting the unexpected position sensor value as well as the overcurrent condition, but neither MGA or the pump motor were. That makes me think there was a short circuit in MGB (the main drive motor, i.e. the one not connected to the engine).
Frankly I'm amazed that such a short could even be allowed to occur in their design. That's just unacceptable.
 

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I also got the some of the same codes in my 2017 Volt. Required replacement of the transmission, took 2 weeks to get the car back.
Posted details at:
http://gm-volt.com/forum/showthread...to-Park-quot-Lost-Power&p=4063345#post4063345
In the same thread I've added the codes that showed up on my 2017 Volt, some of which are not in listed here:

DTC P1B42: Drive Motor 2 Control Module Hybrid/EV Battery Voltage Isolation Sensing Performance
DTC P07A3: Transmission Clutch 1 Stuck On
 

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I got that same error on my 2016 LT volt “shift to park” when it was already in park. I had to get my car towed for it. The dealer did not cover the expense. Apparently the battery has a 8 year warranty, but the limited warranty that would normally cover this is just 3 years, and it happened to me not many months past this point. They had to replace my whole shifter.
 

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I got that same error on my 2016 LT volt “shift to park” when it was already in park. I had to get my car towed for it. The dealer did not cover the expense. Apparently the battery has a 8 year warranty, but the limited warranty that would normally cover this is just 3 years, and it happened to me not many months past this point. They had to replace my whole shifter.
The "Shift to park" message can mean several things. In your case it's certainly not the same problem as the OP had, because the OP's repairs were much more extensive than yours.

In fact, you have a very common problem. Search this forum for "shift to park" - there are numerous threads. The good news is that the repair (replacing the shifter) actually is covered under the Voltec warranty (8 years/100k miles). In one of these threads, a GM document was posted that clearly shows that this repair is covered under the longer warranty. Find that, take it to the dealer, and make them refund your money.
 

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I've been having issues with Shift to Park over the past couple months, however with a flick the button it engages.

On the way home from work last night I had this happen.

In my case it logged a P07A3 fault that will not MIL reset, the car will not shift into gear ... dead in the driveway.
I'm wondering with no other DTC faults logged if the problem might be a failure of the shift mechanism.
Seem unlikely that an actual transmission failure would only log one fault.
 

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I have one 2017 Volt and two 2018 Volts. I am intermittently getting the "Shift to park" error on the 2017 and one of the 2018s right now. The 2018 has gotten so bad that I simply now exit the car and lock it if I'm out or plug in the charger when at home. I have an appointment at the dealership for this coming Friday.
 
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