P0C17 and P0C18 Tahoe Hybrid 2008 - Page 3 - GreenHybrid - Hybrid Cars

P0C17 and P0C18 Tahoe Hybrid 2008

  #21  
Old 03-13-2019, 04:51 PM
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Default Re: P0C17 and P0C18 Tahoe Hybrid 2008

There are 2 HV contact relays inside the battery. They are open any time the car is not ready. When power-on diagnostics and sync has been completed, the two relays are closed, and the battery is connected to the HV system. If the battery fails initial check, or is low voltage, the HV relays will not close, and the battery will remain isolated from the car.

In some cases, one relay will energize, while the other will not.

Regardless of any issue with the relay(s), a battery voltage of 213V is the first problem. It is dead, and it is below the 240V threshold for Jump Assist to work. Neither relay affects the BATTERY voltage reading as the reading is taken from the sensing harness, not the main leads.

You're grasping at straws. HV battery is DEAD. Jump Assist will not function because battery is < 240V.

You're going to have to open the HV battery to diagnose.
 
  #22  
Old 03-13-2019, 04:56 PM
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Default Re: P0C17 and P0C18 Tahoe Hybrid 2008

Originally Posted by S Keith View Post
There are 2 HV contact relays inside the battery. They are open any time the car is not ready. When power-on diagnostics and sync has been completed, the two relays are closed, and the battery is connected to the HV system. If the battery fails initial check, or is low voltage, the HV relays will not close, and the battery will remain isolated from the car.

In some cases, one relay will energize, while the other will not.

Regardless of any issue with the relay(s), a battery voltage of 213V is the first problem. It is dead, and it is below the 240V threshold for Jump Assist to work. Neither relay affects the BATTERY voltage reading as the reading is taken from the sensing harness, not the main leads.

You're grasping at straws. HV battery is DEAD. Jump Assist will not function because battery is < 240V.

You're going to have to open the HV battery to diagnose.
I am thinking of buying 40 hybrid 7.7 volts cells and just changing the packaging. Thanks for the quick answers. I just donít want to waste money and try to find the best option.
 
  #23  
Old 03-13-2019, 05:02 PM
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Default Re: P0C17 and P0C18 Tahoe Hybrid 2008

First, 7.7V cells mean nothing. As you can see from data provided in other threads, modules with good voltage can have crap capacity.

There is ONE supplier on ebay that I trust:

https://www.ebay.com/usr/tedb8?_trks...72.m2749.l2754

He sells them for about $55 each and gives a one year warranty. I've purchased them and tested them, and they were excellent. Everything else is a crap shoot.

Alternatively, you can do what Jamie did - purchase 2X Prius C batteries (cool climate and < 60K miles) and use those to build.

BEFORE YOU DO ANYTHING LIKE THOSE OPTIONS, YOU NEED TO OPEN THE BATTERY AND CONFIRM THAT YOU HAVE AN ACTUAL BATTERY ISSUE. All data thus far points that direction, but you need to be certain.
 
  #24  
Old 03-13-2019, 05:17 PM
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Default Re: P0C17 and P0C18 Tahoe Hybrid 2008

Originally Posted by S Keith View Post
First, 7.7V cells mean nothing. As you can see from data provided in other threads, modules with good voltage can have crap capacity.

There is ONE supplier on ebay that I trust:

https://www.ebay.com/usr/tedb8?_trks...72.m2749.l2754

He sells them for about $55 each and gives a one year warranty. I've purchased them and tested them, and they were excellent. Everything else is a crap shoot.

Alternatively, you can do what Jamie did - purchase 2X Prius C batteries (cool climate and < 60K miles) and use those to build.

BEFORE YOU DO ANYTHING LIKE THOSE OPTIONS, YOU NEED TO OPEN THE BATTERY AND CONFIRM THAT YOU HAVE AN ACTUAL BATTERY ISSUE. All data thus far points that direction, but you need to be certain.
I watched the voltage on the modules is the minimum that I saw is 10.1 and the maximum is 12.1 volts
So one cell 5.05v double 10,1v
 
  #25  
Old 03-13-2019, 09:03 PM
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Default Re: P0C17 and P0C18 Tahoe Hybrid 2008

Terminology:

block = 20 voltages the car monitors comprised of 2 modules
module = 6 cell battery, 40 per HV battery pack
cell = single 1.2V NiMH cell, 6 per module, 240 per HV battery pack

If you're able to monitor block voltages with the diagnostic tool, and all 20 blocks are between 10.1 and 12.1V, then you have confirmed your battery is completely toast.

Very hard to imagine how they could get that way unless the battery sat for YEARS.

Personally, since the vehicle may have other issues, I would attempt to charge it per my instructions. Will probably take you about 2 hours to get it all hooked up, 6 hours to charge and then ?
 
  #26  
Old 03-13-2019, 09:10 PM
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Default Re: P0C17 and P0C18 Tahoe Hybrid 2008

Originally Posted by S Keith View Post
Terminology:

block = 20 voltages the car monitors comprised of 2 modules
module = 6 cell battery, 40 per HV battery pack
cell = single 1.2V NiMH cell, 6 per module, 240 per HV battery pack

If you're able to monitor block voltages with the diagnostic tool, and all 20 blocks are between 10.1 and 12.1V, then you have confirmed your battery is completely toast.

Very hard to imagine how they could get that way unless the battery sat for YEARS.

Personally, since the vehicle may have other issues, I would attempt to charge it per my instructions. Will probably take you about 2 hours to get it all hooked up, 6 hours to charge and then ?
I bought the car at auction and can't tell how long it was standing but on the history of the Vin not long time ago drive and serviced
 
  #27  
Old 03-14-2019, 12:10 PM
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Default Re: P0C17 and P0C18 Tahoe Hybrid 2008

The only way to charge this one is to do it S Keith's way.
 
  #28  
Old 03-16-2019, 08:13 AM
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Default Re: P0C17 and P0C18 Tahoe Hybrid 2008

I had a construction equipment service tech come out to check an electric manlift this week (the guys had left the keyswitch on and it had sat for a couple of weeks without use). The massive 48V battery pack had dropped so low in voltage that it was barely readable and well below the min for the charger to kick in and charge it. He drove another manlift over beside it and hooked the batteries together with jumper cables, (I was waiting on him to pull a beer out and say Hey Hold My Beer) This somehow fooled the charger into seeing enough voltage to start charging. He removed the jumper cables after a few minutes and it continued charging and the manlift worked great after that. Of course these GM Two Mode vehicles are so rare that you might not exactly have one handy to use as a booster LOL. On a construction jobsite there can be hundreds of manlifts as far as the eye can see. Just an interesting tidbit...........................there is probably more than one way to skin this cat.
 
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