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Discussion Starter · #1 ·
Hello, I have a 2013 Volt, 50k miles in good condition.
Cruising along at highway speed on either battery or gas and suddenly both sides grey out and total loss of power.
Power steering and power brakes stay on until stopped then cut out.
Try to restart and "Initializing, wait to shift" screen comes on for about 10 sec then the greyed out screen again. If i wait long enough, it will occasionally restart and proceed normally.
If I disconnect the 12v battery and reconnect, it will restart but will stop again.
Code reader gives:
P0A45 (drive motor position sensor circuit) and
P0AC4 (hybrid power train control module)
12.8 volts detectable in the trunk, and under the hood.
Has anybody ever seen this condition and know of the solution?
Thanks in advance for your comments.
 

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Is it possible that the 12v battery is just unable to deliver the amperage needed? Sometimes the volts check out OK but they can't deliver the amperage when needed. I just checked the voltage on my 12v battery in the trunk of my 2017 and got 13.35v.

Edit: the car was plugged into the 120v charger at the time (charging had completed) so that 13.35v may be high due to being plugged in.

Mike
 

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If the 12v battery has never been replaced this is a place to start. Also connections. I'd look at the coolant level as well. There is a sticky which explains the rather confusing situation. If it's not either of these it could be many things, including loose connections or even hungry rodents. Trips to a dealer are never fun bit sometimes they're necessary.
 

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At 50k miles your 2013 should still be under the 8yr/100k mile Voltec warranty and it sounds like one or both of those would be covered under that. Take it to your dealer and have them do a proper diagnostic on it.
 

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Concur with "take it in". 12v battery issues aren't usually this consistent. Sounds like there's a bonafide fault, which will take at least a module reprogram to fix, presuming it's NOT actually a bad motor sensor. If it is, it's probably "new motor time", which is also Voltec warranty.
 

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Discussion Starter · #6 · (Edited)
Thanks for the responses.
Forgot to mention, engine light comes on then self clears after several miles.

Mike: I get higher voltages when it is plugged in too. I believe the biggest draw is to start the engine which it did consistently fine when it ran after restarting from the fault.

Don: Coolant level, wow. Can you please direct me to the "sticky" you refer to. Newby user :) thanks.

Mr. Flash: Unfortunately the car has a salvage title which means zero warranty to me :( The car ran perfectly for the first 20k miles of my ownership so I'm thinking it is not related to that event. (frontal impact, no frame/suspension damage, no air bags deployed, crumple zones replaced only) But I could be wrong.

Mr Sop: When you say things like "take it in" or "new motor time" what I hear is "$$$$$$$$$$" haha.

This problem seems to fairly well documented on the internet, I just cant find what anybody did to fix it...what the root cause is. Does anybody out there have a contact that keeps an eye on this kind of stuff?
Might be worth mentioning that I work in an aerospace electronics shop, so cracking open a module and reflowing solder joints or replacing components is totally doable.

Any suggestions are super helpful. Thanks.
 

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If I was in your situation, I think I'd see if I could find another vehicle with a compatible 12v battery that I could borrow just to test that. Then maybe check all the ground wires you can find. Faults in multiple computer systems can sometimes be a bad ground.

Edit: I was able to find this:

Date Reported
SEPTEMBER 01, 2013
NHTSA Reference
#10053870
TSB Reference
#SB-13202
Description: CHEVROLET: ON SOME VEHICLES, WATER MAY TRAVEL ALONG DRIVER MOTOR 2 POSITION SENSOR WIRE SET A DIAGNOSTIC CODE, IN WET WEATHER, AND CAUSE CHECK ENGINE LAMP TO ILLUMINATE AND WOULD NEED TO REPROGRAM POWER INVERTER MODULE. MODEL 2011-2013 VO

Edit 2 (did some more reading, sorry):

Based on this and other info: http://www.autocats.ws/manual/chevrolet/tis0911/en/documents_2012/Volt/SM-R/92422548.en.html

It looks like the motor position sensor is either sending a garbled signal or the motor control module is faulty and isn't picking up the signal properly. The sensor is likely producing something akin to a square or sine wave and the motor control module probably examines the signal to determine motor speed and/or position. Looks like the signal is read as "garbage" by the motor control module either due to a bad sensor or a bad module (or even a bad wiring or water intrusion problem) and that throws P0A45. Due to the P0A45, the system throws P0AC4 to turn on the MIL.

Probably still worth checking the battery and grounds first though, as that's likely the easiest.

Mike
 

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Don: Coolant level, wow. Can you please direct me to the "sticky" you refer to. Newby user :) thanks.
...
This problem seems to fairly well documented on the internet, I just cant find what anybody did to fix it...what the root cause is. Does anybody out there have a contact that keeps an eye on this kind of stuff?
Here is the info about the coolant level. http://gm-volt.com/forum/showthread.php?119089-Battery-Coolant-and-other-Fluid-Levels-FAQ Note that a code can have several different underlying causes. It's not quite as simple as having a code determine a cause. You can have a failure which causes another failure which causes a fault that throws a code. That's why people are suggesting a failing 12v or low coolant. Those can lead to different faults.
 

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Any car that was in a wreck, I'd replace the 12v battery just for grins. Even AGM is not all that shock proof. An intermittent connection/ground could cause these symptoms as well.
 
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