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Discussion Starter #1
First off I have a 2016 Volt LT, 38k miles.
Last wednesday my wife had taken the volt to work, a 3 mile drive, it had about 19 miles on the HV battery and had been sitting in the driveway 3 days since the last time it was driven. Anyway, I get a call that afternoon from her that the car was dead. She said she had pushed the start button, it started to initialize then went dead.
So when I initially drove up, the parking lights were dimly lit, the car was completely dark on the inside with the door open and there was no response to the key fob.
Not knowing that there were alternate "jumping" posts under the hood, I open the rear hatch and jumped the 12v battery. Lights came on inside and I noticed a CEL with a "Service Theft Deterrent System" message. In driving it home I notices several changes... 1- The Trip A had reset to 0, 2- the IPC display had changed form classic enhanced to a generic green oval showing speed and trouble message and no longer showed the battery or ICE status, they were blank, 3- the "Normal" mode had changed to "Tour". Oh and another odd thing was when I jumped the car I got a Onstar text saying the Volt had completed charging.
The next morning it unlocked like normal with the key fob, static battery voltage was 12.6 volts. I pulled the following codes 1- P1F64, 2- P2534, 3- P0AC4, 4- P25C9, 5- P1F64 and 6- P2534. I started the car and checked the charging voltage...14.6vdc at the battery. Connections seemed tight.
The drivers display had changed back to Classic Enhanced and Tour mode had reverted to Normal mode:confused::confused: and the Service Theft Deterrent System message was gone. I cleared all dtc codes. I drove the car a few miles and cycled the modes from normal to hold to see if the ICE would kick in, it did. I charged the HV battery with no issues.
The 12v battery shouldn't have discharged sitting in a parking lot for 8.5 hours..... Should it?
I'm going to load test the battery tonight. Thanks in Advance for any comments of solutions.
 

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service mode may have started by accident

Monitor the 12 volt battery for a few days via a power port DC volt meter just after stoping the car and before you open the door.

Starting with a low battery will give bogus codes that will clear BUT best to go look them up.

after a few restarts have onstar or auto prts store get codes if the engine light is still on.
 

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Discussion Starter #3
Service Mode? What is it and how do you get to service mode? Would service mode change Normal to Tour mode? If she accidently put the car in service mode, would the car not shut down when she exited and closed the door?
 

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Service Mode? What is it and how do you get to service mode? Would service mode change Normal to Tour mode? If she accidently put the car in service mode, would the car not shut down when she exited and closed the door?
You can unintentionally start the Volt in service mode if you press an hold the start button for too long (normally you only need to press the start button for 1 second.) The Volt will start but the accessory power module will not turn on; the Volt's 12V systems will be running solely on the 12V battery until you shut off the Volt.
 

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Also, you may have been seeing the Cadillac ELR display. Folks have occasionally mentioned getting it on the Volt after 12v power issues. It eventually returns to the regular Volt displays.
 

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Also, you may have been seeing the Cadillac ELR display. Folks have occasionally mentioned getting it on the Volt after 12v power issues. It eventually returns to the regular Volt displays.
Need. Gonna go short my 12v so I can see that! ;)

Mike
 

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Discussion Starter #8
Sorry for the delay, but the 12v battery tested fine. Still no concrete answer as to what happened, just speculation. Service mode?? Cable terminations?? Prius gremlin??
 
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