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Discussion Starter · #21 · (Edited)
Both battery packs were good, just the software was borked making them appear bad.

The first battery (original pack that came with car) was returned when they installed a second pack to replace it.

The second pack is still in the car, and working fine so far with the new software. As of now, it has about 50% of it's state-of-charge bars back since being plugged-in to AC outlet. It had zero state-of-charge bars when I got it back from dealer.

Hopefully the next CT6 hybrid owner with a Service High Voltage Charging System fault will have a much more straight-forward service experience.
 

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Discussion Starter · #22 ·
FYI, anyone know how many hybrid CT6s are in the United States? I know it's not many, they only sold 2017 and 2018 model years.
 

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This whole thing started with your CT6 because the coolant in the battery coolant reservoir sloshed and glitched the low coolant sensor?

The handling of this sounds exactly like the Volt where they have to reflash a computer module to clear the codes once the coolant sensor condition throws the errors. From some prior threads, this whole thing got hosed up because there was a battery fire on a wrecked Volt sitting in a junk yard, and the federal politicians got involved with this because the Volt was a target of anti EV propoganda. Then end result of the negative political influence was this messed up software algorithm for clearing latched codes.
 

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Good morning, I have a 2017 ct6 hybrid too. Yesterday for the 3rd time since I purchased, I got the service high voltage battery message.I'm in n.j. they reset it every time but not a permanent fix. Bought it new.only dealer that services this near me is Crown Cadillac.Another call
 

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Good morning, I have a 2017 ct6 hybrid too. Yesterday for the 3rd time since I purchased, I got the service high voltage battery message....
Are you sure this isn't the msg that happens from a dip in the grid voltage while charging?
Will it go away on its own after a few charges to full?
 

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To the OP, I feel for you and your 5.5 week ordeal. I believe that the driving scenario you described caused the fluid sensor to trip and the software to give you the message. All that followed needn't have been necessary had GM taken to heart the root cause of such "failures" with the Volts and conveyed the solution to Cadillac via a company-wide memo (or something). Communication...something that GM needs to work on.

To give you back your Cadillac without having recharged the battery is so in bad taste (as in adding insult to injury).
 

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Well I am now in a similar situation. I have been able to turn off the warnings, reset using standard OBD scanner. Added a little more coolant and problem seemed to go away. Temp here today is around 100 and darn warning light and the dreaded warning appeared. Plugged it in and it isn’t charging.

Not going to attempt reset but will go to the dealer on Friday early and start the fun.

This dealer has been friendly to me and even took back a Suburban that had a vibration and lived in the shop for months.

So we have history.

Will see what Friday brings!

Happy 4th of July to all!

Dave

CT6, Escalade ESV, 82 Corvette CE, 78 Pace Car
 

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Well, the car is now going to be a fixture at the dealership. Seems like they needed to do service bulletin N182153620, Auxiliary Transmission Pump Current High DTC P0C28, Loss of Propulsion, release 09/18/2018.

Also, was told they have to remove rear seat and cut a hole in sheet metal to remove/install a part. Problem is either the patch to fix the hole or the part is quote "not available".

So I am in a XT5 that is nothing like the CT6, for how long??? No warm fuzzy feeling here.

Dave Text Document Paper Font Paper product
 

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Reading this thread, I am amazed how many dealers just replace the entire battery pack when they get a code they can't diagnose. And in your case there was nothing wrong with the pack. What if this had been an out of warranty vehicle and the dealer charged you for a whole new battery when in fact there was nothing wrong with your battery and you likely would have the same problem you came in with?

GM needs to step up their dealer / technician training so they can properly diagnose faults on all of these Voltec / hybrid cars.

I used to work on large airplane maintenance systems where time spent on the ground troubleshooting equals money lost and in a big way. Can you imagine an airline replacing a jet engine because they got some fault code they didn't understand? "Well, let's just throw a new engine on it and see if the code clears!" That seems to me what some GM dealers are doing with replacing the whole battery pack before the root cause is identified.
 

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Reading this thread, I am amazed how many dealers just replace the entire battery pack when they get a code they can't diagnose. And in your case there was nothing wrong with the pack. What if this had been an out of warranty vehicle and the dealer charged you for a whole new battery when in fact there was nothing wrong with your battery and you likely would have the same problem you came in with?

GM needs to step up their dealer / technician training so they can properly diagnose faults on all of these Voltec / hybrid cars.

I used to work on large airplane maintenance systems where time spent on the ground troubleshooting equals money lost and in a big way. Can you imagine an airline replacing a jet engine because they got some fault code they didn't understand? "Well, let's just throw a new engine on it and see if the code clears!" That seems to me what some GM dealers are doing with replacing the whole battery pack before the root cause is identified.
Mary Barra needs to shake things up if she wants to be the number one player in the BEV market. Or is the game plan to only sell ICE trucks and SUVs in the States and be a BEV player in China? If the latter, then the crown is Tesla's by default.

Actually, I can easily make a case for sticking with ICE in the States, starting with her dealers and their service departments...sad.
 

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Jeez, this is turning into a nightmare. The sensor for the Drive Motor Coolant Sensor is somewhere behind sheet metal behind the rear seat. They have to remove the rear seat, cut a access hole in the metal to remove the sensor (Document ID 4516638). Then they have to repair the hole with a patch (Document ID 5028369).

Well all would be good if there were any patches (p/n 84098877) around... they are not available and on B/O from GM.

So my car is parked, I actually have gone on-line and tracked down a dealer in Texas that has 2 of these patches in stock. The other dealer I spoke with has 2 but they are on hold for customer cars, so if you use Swell Village they are probably holding them for you.

I have the Documents referenced and also service Update N182153620 available but can't figure out how to upload them here.

More fun in the hot sun in Georgia!

Dave
 

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Just ran across this thread after encountering the same high voltage error message in my 2017 CT6 Plug-in. I was able to get where I was going and back home since I had a full battery but now it won't charge. I bought the car new and have less than 7000 miles on it. As luck would have it, I just moved and my new location has no Cadillac dealership; the previous dealership is about 90 minutes away so I guess I'll be making that trek later this week. I'm a bit worried about what will happen on the way since I know I won't make it that far on battery; I suppose I could switch to "Hold" mode and go on gas the whole way...
 

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My 2018 CT6E was purchased new in March 2020 and must have had the update as it is been fine for +6,000 miles.
 

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All,

I just recently bought a 17 CT6 Hybrid with roughly 28,500 miles on it and have encountered the same issue that you all have had. I purchased the car from Carmax and for the first week the car drove great with no issues. After plugging it in for a few days with no issues I got the "Service high voltage system" alert and now the car won't charge at all. I have been driving it on strictly gas but wanted to get feedback on if this will cause any issues with the light on. From the sounds of it this issue is caused by a glitch somewhere?

I am taking it to the Cadillac dealership in a few days. I am getting the PIE00 code and it also shows a recall for drive motor power inverter module.

Can anyone provide any feedback or advice on this issue?
 

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All,

I just recently bought a 17 CT6 Hybrid with roughly 28,500 miles on it and have encountered the same issue that you all have had. I purchased the car from Carmax and for the first week the car drove great with no issues. After plugging it in for a few days with no issues I got the "Service high voltage system" alert and now the car won't charge at all. I have been driving it on strictly gas but wanted to get feedback on if this will cause any issues with the light on. From the sounds of it this issue is caused by a glitch somewhere?

I am taking it to the Cadillac dealership in a few days. I am getting the PIE00 code and it also shows a recall for drive motor power inverter module.

Can anyone provide any feedback or advice on this issue?
Mine starting doing SHVS in April 2020. The dealership updated the propulsion system in the event the engine wouldn't turn on when battery was depleted. But I have been getting the codes every couple of days after clearing them.

P1e00
P1ffe
P1fff

I'm due for a oil change and will address the issue at the time.
 
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