Re: Tahoe/Yukon Hybrid Problems: Brake Loss, Service Traction Control,Service Stabili
 

I have a 2008 TaHY. I have had many problems with it throughout its life. It currently has close to 140,000 miles. My problems didnt really start until about 70,000 miles.

The First big problem: I eventually had to contact GM customer service (who was very helpful) to get the problem fixed. I had taken it to multiple shops for high oil burn, loss of oil pressure and rough running engine. They just kept making these minor fixes, which I had read online where just temporary fixes bc the engine had to be taken apart to fix the main problem. Finally the engine blew at MN in the middle of nowhere in Kansas, with me, my girlfriend and 2 kids in the car, with a huge snow storm coming in 24 hrs that ended up closing the interstate. It turned out to be a broken lifter and a sensor (the one that the other threads on the GM site said was the problem) was bad. The mechanic told me he had seen it before and the sensor was the cause of the whole sequence of events, but bc of the sensors location (somewhere in engine) nobody wanted to fix it. Since this episode, I have not had any problem with oil burn or rough engine idling, but it really pissed me off that GM didnt want to fix the problem, they just kept trying to make fixes to prolong the major problem, hoping that my warranty would run out. I will say it didnt break until 107,000 and GM customer service paid for most of the repairs bc I had brought the truck in so many times.

So now, I have started having problems with the Service Traction Control, Service stabilitrac, and Brake lights coming on, but the check engine light does not come on. I do not lose my brakes, but they do become "looser," taking more pressure to get a response. My truck is in the shop for the second time in a week. Originally they told me it was my battery, and they had to charge my battery just to finish the diagnostic tests. They recommended me getting a new battery. The old battery was barely a year old (I have gotten 6 batteries in 5 years), and it was covered by warranty. So i replaced old battery with a new one and the problem is still occurring.

Wondering if anyone was still having the same problems and what was their resolution.

BTW if the dipsh** who keeps saying to kill the thread is still monitoring it, I would rather you keep your comments to yourself and move on with your life. But all other comments are encouraged.

Re: Tahoe/Yukon Hybrid Problems: Brake Loss, Service Traction Control,Service Stabili
 

since you are first time poster, who is this person that wants to close the thread? all GM/site is monitored if not I get alerts to know that. since you were just talking about your hybrid's problem, can you care to elaborate what maintenance was done to it? new or used? I assume from your introduction sentence it was a new purchase? what oil was used throughout its life etc? what fuel was used etc? 4WD or 2WD? thanks.

Re: Tahoe/Yukon Hybrid Problems: Brake Loss, Service Traction Control,Service Stabili
 

padge, the brake computer should have stored codes in it after it lit up the instrument cluster like you describe. However, if they CLEARED the codes first or disconnected the 12V battery, the evidence is lost. Any time your hybrid sends you a message, some computer will remember why.

Trouble is getting the service people to recognize this and NOT clear first and hope they come back.

Re: Tahoe/Yukon Hybrid Problems: Brake Loss, Service Traction Control,Service Stabili
 

The guy I was talking about posted a couple times previously about closing the thread was Jet1.

I bought it new at the end of 2008. It is a 2wd. I had it serviced mostly at dealerships at first and then I either got it changed at a local mechanic or I did it myself. I use Castrol GTX and later high mileage oil. As far as gas goes, I use standard 87 octane gas.

Previous repairs/services - 2 oil burn tests, head gasket, fuses, and a sensor all prior to lifter breaking. Then a new lifter, plus replacements for parts to get to lifter. A sensor (not exactly sure where the two were) but I think one was in the oil pan and one in the fuel system. These repairs fixed the oil burn and rough engine.

Currently - First time I took it in for the service on stabilitrac, traction control and brake warning light plus a soft brake pedal, they ran the test and the service tech said it came back with 20 different codes but most of those codes traced back to a weak battery. So I replaced the battery and a the next morning the same lights came on and the brake pedal remained soft.

Update - I took it back again today to get the previous problems looked at and it turns out that I had a cracked brake caliper that was leaking. They repaired the caliper today and so far it is running great without a single warning light coming on. Also, surprisingly the transmission is even shifting better (would occasionally stick in second lately). I had a really good technician these past two trips and he was able to get thru all the codes (said there was a couple after I replaced the battery) and hopefully find the root of the new problems. So far I have been really impressed with his knowledge.

Re: Tahoe/Yukon Hybrid Problems: Brake Loss, Service Traction Control,Service Stabili
 

I have used dino oil before but have changed to full synthetic since it gives guaranteed performance up to 15k miles esp for extended performance mobil 1. the LFA engine of the hybrid has cylinder deactivation and uses the same cylinder bank each time it goes to V4. I think lubrication is crucial which dino cannot provide even during the advent of multivalve engines and variable valve timing. your issue of using dino oil must have contributed to the problem. hopefully it has been fixed. I have 150k miles on my engine with no oil burning or oil starvation problems. I have used only full synthetic since break-in oil which was also mobil 1. since you had your engine fixed, it is not too late to start using one.

Re: Tahoe/Yukon Hybrid Problems: Brake Loss, Service Traction Control,Service Stabili
 

Thank you for the responses. I will switch oil just to be cautious. I will say that when the engine was repaired, the service manager told me to start changing my oil about half as often as the manual recommends, just to be safe, so I have been doing this for about the past 35,000 miles. If I switch to full synthetic, do you think I would still need to change my oil more often, or how long do you wait between changes?

So far the fixes are working. We took truck on a trip this morning (couple hours to volleyball tournament) and even my girlfriend said it was running much better and could tell a big difference.

Re: Tahoe/Yukon Hybrid Problems: Brake Loss, Service Traction Control,Service Stabili
 

The brake caliper would send all sorts of warnings since fluid would be missing. Weak pedal is expected there. Not hybrid unique. Now the weak battery. Do you let this vehicle sit in Accessory and listen to "the game" or other tail gate like activities?

This vehicle when the total drive system is not on... ( put it in gear and go ) has rather large 12V system demands. Sitting in Accessory for more than about 10 minutes may put you in a bad place. Sitting in Run but not "running" is even worse. There are missconceptions that the engine has to be physically turning to generate 12V. Not so, you have a "solid state" alternator. Any time the vehicle is ready to go in EV , auto-Stop, or running fuel burning, it should be charging. It is best to let the vehicle Auto-Stop and engine cycle HV charge mode for tail gating.

If sitting in Acc/Run is not happening, then there may be a power vampire out there. Something that is not turning off.

With all the computers and solid state devices, the electrical "leakage" is large. So sitting parked for more than a week could put you in a bad place.

Re: Tahoe/Yukon Hybrid Problems: Brake Loss, Service Traction Control,Service Stabili
 

I use mobil 1 extended performance and my caddy's maintenance minder changes it every 13k-15k miles. but I usually change it when it has 30% left or about 10k miles. it is cost effective with maximum engine oil performance.

Re: Tahoe/Yukon Hybrid Problems: Brake Loss, Service Traction Control,Service Stabili
 

Well it seems like I'm the latest victim of the loss of brake pressure, stabilitrak, brake warning, check engine light, etc. I purchased my used 2008 with 135,000 in December. So far no complaints. I've read plenty of the posts on here wondering if I am just lucky with mine. This weekend I jumped into the Yukon to run to the store. I started the engine and shifted into reverse right away to back up. I got all of the above lights/problems. I thought I remembered someone saying you may get those messages if you don't let the vehicle boot up prior to shifting into gear. I shut it off, let it sit for a minute and restared with no continued faults except the check engine light still on. I figured no big deal as it's probably on due to the codes thrown into the computer. This morning the check engine light is back off, all is well. Driving home after work today, radio on, air conditioning on, driving for about 10-15 minutes a guy in front of me does a quick lane change and turn in front of me. I have to step on the brake hard but not super hard. When I did this the brake pedal went further than normal and all of the above warning lights illuminated on the instrument panel. I slowly pull into a parking lot and the pedal goes almost to the floor. I shut off the vehicle and restart but the lights come on as soon as I press on the brake. I do this several more time, check brake fluid reservoir but the same results. After about the 6 time restarting, I hear a motor running ( brake accumulator ? ) and the pedal begins to get firm again and the warning annunciators remain extinguished. I continued driving home slowly with no further faults. Didn't think of checking the voltage until everything was good, at that point it was indicating 15vdc. My positive post of the 12v battery has corrosion so I'm going to clean that and see what happens next.

Re: Tahoe/Yukon Hybrid Problems: Brake Loss, Service Traction Control,Service Stabili
 

You need to get the codes and associated freeze frame data with them. This is a complicated vehicle with a networked control architecture. Clearing and re-setting codes the old-school way is just a lesson in frustration. With data comes a possible solution. It may not even be hybrid related.