Good morning,
I have not had any luck finding any information online for the errors I am receiving on my 2010 GMC Yukon Hybrid. For starters, it has 113k miles on it, bought used. We first started noticing a message on the dashboard reading "Service Hybrid System", but no other big issues. This error comes and goes, mostly appears after accelerating from auto stop. Sometimes the accelerating seems like I am about to run out of gas, is the best way to put it, like it is thinking really hard to accelerate. Also, if I come to a complete stop when the dash read "Service Hybrid System", the car will completely shut off and throw the error message "Service Power Steering". I have to turn the car off and then back on. In extreme cases, I have to reset the engine battery. I never have issues with power steering, so the error message is a little confusing.

Things we've done to try and fix this:
We've completely recycled every cell in the hybrid battery. All cells are reading within the range they should be. As far as I know the hybrid battery has not been replaced.
All fuses are fine.
Checked power steering motor.

We are taking it up to the GMC dealership this weekend to scan for codes and get a diagnosis.

Has anyone had this issue before or can anyone point us in the right direction?

Thanks!
Nicole

 

What DTCs were reported?


What does "completely recycled every cell in the hybrid battery" mean?


When you say, "all cells re reading within the range they should be," what does that mean? I've processed thousands of modules, and I can tell you that it takes me at least 2-3 weeks and about 8 hours of touch time to make that statement.


Are you telling us that you pulled the battery and checked all 40 modules without reading the DTCs?


The acceleration performance issues you describe are highly indicative of a failed hybrid battery.

 

My husband would be able to better answer that, but yes, we took the hybrid battery out and checked all 40 cells. It took him about 2 weeks to go through the whole process. Even cleaned every connector and all cells appeared to hit the correct voltage/amps and were insync after it was all said and done. He is VERY proficient in all mechanical issues, but the hybrid game is completely new.
We have a code reader, but not one that can give us accurate codes for this make/model. A hybrid mechanic in our area even told us that he is unable to obtain the computer software from GMC to read these codes. The GMC dealership is the ONLY place in our area that can provide us the DTCs, and just that alone is $300-400....so yeah, we did this without getting true DTCs.

 

First, I find it astounding that someone would opt to go through that without trying to get the DTCs. The majority of consumer grade readers mostly suck when it comes to hybrids. I have found that O'Reilly has substantial success in reading codes from all hybrids due to their use of Bosch brand code readers.

The aforementioned 2-3 week timeframe also requires about $7000 worth of custom equipment, 3 years of experience testing thousands of modules, and the ability to move about 300A of current at 11-15V (about 4000W of power).

"Correct voltage/amps and were insync" is meaningless unless you have the experience and equipment to make that determination.

The only information you have provided points directly at a hybrid battery failure; however, the only prudent course of action is to check out the 12V system to make sure it's 100% working. 12V battery holds voltage AND passes a load test, then proceed directly to O'Reilly to try and read codes (they can check your 12V too). If that doesn't work, to the dealership you go.

If you would like to involve your husband and provide the data he collected, I would be happy to evaluate it and provide useful feedback. However, I will need to understand exactly what was done in detail.

Good luck,

Steve

 

Dear Team,
My GMC Yukon 2008, recently, since 2 months ago during in driving the "Service Power Steering" appears on the dashboard sometimes and the steering becomes hard to drive (i mean difficult to turn). Then when i turn off the car and turn it on again it disappears on dashboard and appearing again in few minutes. Can someone help me and explain it to me? Should i replace the power steering electric motor or something need to do?

 

hi if you would be able to help me out as well
my truck was running fine a day before and the next day it just wouldnt start,the service hybrid system message comes on but it won't crank over or do anything but kill my battery after a few tries, i thought ot would be my battery so i bought a new one and tries it. No luck. I havnt really done anything about it due to kot having money atm but any help would be appreciated

 

I have a 2009 Yukon hybrid and it’s giving me a message service battery charging system, service hybrid system, and service power steering, also my steering wheel is very hard to turn, can you help please? I replaced my 12v battery and it stays on for about 10 mins then it dies. I thought maybe replacing battery 12 v help but it didn’t.

 

The OP has probably gotten rid of their problem vehicle by now after 1 1/2 years. I would have liked to hear what the OP's husband actually did for testing.......
Jose1981 so what actual codes does your Yuk have? A good newer model code reader of just about any kind should pick up the basic codes. I have a cheap Innova that reads the basic codes like POAC4 and POBBD, (these are a couple of common ones that indicate a problem with the Hybrid battery pack).

A large percentage of 10 year old high mileage GM Hybrid packs likely have a lot of severely degraded modules. There are a lot of internet posts where people have only replaced a few bad modules in a Toyota Prius pack and drove the vehicle for a long time. I do not think from my experience that is going to be as successful on a GM pack. I have seen it stated several times that the GM control system is a lot harder on the modules. Maybe the GM control system has to do that in order to move these 6000 lb behemoths around LOL.
From my recent experience if you do a full charge/discharge capacity test on a GM pack you will most likely find that 85% of the modules suffer from severe degradation / cannot be reconditioned and must be replaced. Several very good threads on here about battery testing and as stated it takes some specialized equipment and is a time consuming project if done correctly.
These GM Two Modes have several things working against them Low production volume / discontinued product / limited availability of replacement parts that will only increase in price and scarcity. You can quite quickly spend more than your vehicles current value if you farm out the repairs. we are all kind of stuck between a rock and hard place I guess. Jose post up your codes and someone here can probably help you through your diagnosis. The system is complicated but not beyond the abilities of a normal individual willing to learn.

 

have you tried M mode make sure it's in tow mode
so everything will run off the generator instead your gas miles WILL drop to normal Tahoe 6.0L
This is perfectly normal
which is about 50% less so your looking at 10 city and 13 highway...


at some point the engine will stop starting as it's a HIGH speed start by the 60KW electric motor..