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2012 Service High Voltage Charging System

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Howdy!

I’m posting as a last ditch effort to help before I have the dealership drop the battery in my poor Volt. I have a 2012 with the Service High Voltage System message for about 1 month now. The car drives fine, battery doesn’t charge (it does regenerate a little just from normal regen braking — not sure if that makes a difference). I had the same message last year in December which was resolved by updating the BECM. I took it to the dealer and basically he said he needs to drop the battery in order to diagnose. He said this after all of his initial diagnostic tests didn’t show the root cause of the problem. The biggest thing according to the mechanic is that the “insulation resistance test” is showing 0.0 kohm.

I had him replace the coolant level sensor and that did nothing. The cost for just the labor to drop the battery is over $1k so I’m hoping someone else has an answer that doesn’t involve that.

I’ve attached some reports from the dealership. Thanks so much for all the input!

P.S. I had a Volt tech from another group tell me that if the insulation test was actually 0.0 kohm, the car wouldn’t even start. The mechanic ran the test twice and came back 0 both times.
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I've not seen many cases on here where there was a solid short like you are reporting. Non-approved coolant (Dex-Cool concentrate and deionized water) could potentially cause that error. No isolation would be a serious safety risk.

Given that the high-voltage battery appears to have about 10 years of life in it and there are no new cells available to repair them, you may need to decide if it might be time to let this one go based on the news you get.
 

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if isolation was truly zero, I don't think the car would drive at all. That would mean a short in the battery. How would it power the motor?
 

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Discussion Starter · #5 ·
I've not seen many cases on here where there was a solid short like you are reporting. Non-approved coolant (Dex-Cool concentrate and deionized water) could potentially cause that error. No isolation would be a serious safety risk.

Given that the high-voltage battery appears to have about 10 years of life in it and there are no new cells available to repair them, you may need to decide if it might be time to let this one go based on the news you get.
Safety risk? How so?
 

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Hmmm... sorry what do you mean by a sensing issue? Can you give me an example? Sorry I'm not the most electrically inclined person. Thanks a lot.
If the battery isolation was really zero ohms, I don't think the battery would be able to power anything and the car would not drive and charge. It makes me think whatever sensor the car uses to detect the battery isolation is bad.

I am not an expert on this and I don't know exactly how the isolation is detected.
 

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"battery doesn’t charge" is not the thing to say to a car tech as it DOES charge in MM mode..
Need to see why it will not charge from the charge port.

also need to see if you have had all the software re-programming in past recalls.

one step is to just remove a plug on the battery and look for ( water ? )
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When my battery cooling tank float CABLE was replaced then the diagnostic test showed a completely different
(and correct ) battery isolation number.
 

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"battery doesn’t charge" is not the thing to say to a car tech as it DOES charge in MM mode..
Need to see why it will not charge from the charge port.

also need to see if you have had all the software re-programming in past recalls.

one step is to just remove a plug on the battery and look for ( water ? )
------
When my battery cooling tank float CABLE was replaced then the diagnostic test showed a completely different
(and correct ) battery isolation number.
Good suggestions. I had the same symptoms (but different DTC) when my BCM needed to be reprogrammed. Would not charge thru the port but otherwise drove fine.

Seems like an odd design that the coolant tank float cable could zero out isolation resistance.
 

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View attachment 175637
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Howdy!

I’m posting as a last ditch effort to help before I have the dealership drop the battery in my poor Volt. I have a 2012 with the Service High Voltage System message for about 1 month now. The car drives fine, battery doesn’t charge (it does regenerate a little just from normal regen braking — not sure if that makes a difference). I had the same message last year in December which was resolved by updating the BECM. I took it to the dealer and basically he said he needs to drop the battery in order to diagnose. He said this after all of his initial diagnostic tests didn’t show the root cause of the problem. The biggest thing according to the mechanic is that the “insulation resistance test” is showing 0.0 kohm.

I had him replace the coolant level sensor and that did nothing. The cost for just the labor to drop the battery is over $1k so I’m hoping someone else has an answer that doesn’t involve that.

I’ve attached some reports from the dealership. Thanks so much for all the input!

P.S. I had a Volt tech from another group tell me that if the insulation test was actually 0.0 kohm, the car wouldn’t even start. The mechanic ran the test twice and came back 0 both times.
Note that item 14 on the service report indicates the hybrid/ev battery isolation test Passed.
 

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I think it is a testing process
as more items in the test get run and pass more tests are then run

plus some of the recalls changed the firmware to allow (short answer - different values to pass- )

I would not expect a diagnostic machine to print a value as zero when is was really " test not run"

My dealer said they need a volt tech to run their machine when testing volts.
 

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I think it is a testing process
as more items in the test get run and pass more tests are then run

plus some of the recalls changed the firmware to allow (short answer - different values to pass- )

I would not expect a diagnostic machine to print a value as zero when is was really " test not run"

My dealer said they need a volt tech to run their machine when testing volts.
I have made thousands of resistance measurements over my career. When I knew that I was measuring a dead short, very rarely was 0.0 Ohms displayed. So to me, it is questionable.
 
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