2022 Yukon SLT, Transmisiion Hot Idle Engine. HELP!

[Appleman88]

I bought a 2022 Yukon SLT back in December of 2021. The dealership was about 2 hours from home and when I was climbing some hills close to home I started getting alarm bells and an error message " Transmission Hot Idle Engine". I pulled over and called the dealership and they said maybe a glitch. A month later took a trip to Reno and started gettiing the same error. A dealership had me turn on the transmission temperature guage which I founnd that the error will pop-up at 266degrees so I returned from our trip just eyeing the guage and trying to feep the temp below this . Brought the vehicle into a local dealer and they said that it came from the factory a quart low of transmission fluid. I have driven locally on short trips with no problem and the transmisson temp will still climb as high as 250degrees but no alarm.(better that it was, prior to bringing it in, the alarm would have triggered for sure. I had called the dealership back and asked if sometimes reaching 250degrees was normal and they said yes. Can anyone tell me what is a normal range for the transmssion temp. It's hard to believe that riding in the red part of the guage is normal.

Yesterday, had relatives in town and took a longer drive back and fouuth to San Francisco, climbing some hills,...etc. By the time I got home the temp reached 264degrees and there was a loud fan noise hissing behind the drivers side wheel from the engine area. I don't think that this is normal. Does anyone have any advice on this issue? Problem is, you have to drive for atleast 1.5 hours before the temp starts climbing, so how does a mechanic diagnose this, if there is anything to diagnose.


I wish they did not have this temp display because I find that this is all I keep watching when I am driving and am not really enjoying my new 75K purchase. Paranoid that I bought a lemon!

 

[Kpwweb]

That is not normal. Highest I have seen is about 160F. It sounds like the thermostat inside the transmission that regulates transmission temperature is stuck closed.

 

[olyelr]

Yea thats definitely not normal. Maybe the gauge is faulty.

 

[lbenson]

I've seen the 10 speed on my 2018 Denali with the 6.2L reach maybe 205/210 when towing 8,000lb (surf boat with a full tank of gas and the trailer). But that was only in 90+ degree weather towing up some decent hills. Usually well under 200 degrees under normal driving. Dealer said anything that gets close to 250 is not good for it.

 

[Appleman88]

That is not normal. Highest I have seen is about 160F. It sounds like the thermostat inside the transmission that regulates transmission temperature is stuck closed.

Thank you!

 

[Appleman88]

I've seen the 10 speed on my 2018 Denali with the 6.2L reach maybe 205/210 when towing 8,000lb (surf boat with a full tank of gas and the trailer). But that was only in 90+ degree weather towing up some decent hills. Usually well under 200 degrees under normal driving. Dealer said anything that gets close to 250 is not good for it.

Ty for your reply. I don't know why the dealer is telling me that hitting 250 periodically is normal. And this is all happening with a pretty empty cab in 50 to 70degree weather. Have not driven it on a 90+ day yet

 

[olyelr]

250 degree oil temps in a tranny is when it starts killing the trans.

 

[Geotrash]

Ty for your reply. I don't know why the dealer is telling me that hitting 250 periodically is normal. And this is all happening with a pretty empty cab in 50 to 70degree weather. Have not driven it on a 90+ day yet

By the book, transmission temperatures below 265ºF are technically acceptable, but in practice you should never see that temp under normal operation. You should only see that when towing a heavy trailer in very hot weather, such as over a high mountain pass.

In the February 2011 issue of Trailer Life magazine RV Clinic in response to a reader about the maximum transmission temperature allowed in a 2009 Chevy Silverado, the Tech Team had this response.

“General Motors’ in-house towing team expert provided RV Clinic with this statement: The maximum allowable automatic transmission fluid temperature is dictated by the transmission oil itself. The oil begins to degrade significantly above 270 degrees Fahrenheit, so we design vehicles so that in all but the most extreme conditions, the fluid temperature in the transmission sump stays below 270 degrees F.

We allow for up to 285 degrees F in extreme conditions (i.e. towing a trailer with combination loaded at GCWR in Death Valley). But for customer usage anywhere else in the country, even at GCWR, transmission sump temperature should stay well below 270 degrees F. Above this point, certain internal components, such as seals, begin to disintegrate rather quickly. Although newer synthetic fluids can withstand higher temperatures we still recommend this (270F) as a maximum temperature. "

As others have said, you either have a sensor problem or a fluid flow problem through the external cooler. My bet is that the thermostat on the side of the transmission that permits flow through the cooler is not opening. Either way, that dealer needs to get their head out of their ass or I recommend taking it to another dealer.

 

[Appleman88]

Thank You Dave,

Thanks again for taking the time to respond. I have an appointment to bring in the vehicle to a dealer that is closer to my house. In your opinion, even though I did not buy from this dealership, should they be responsible for a rental of another Yukon while mine is in their shop? I feel kind of weird complaining about things when I didn't buy from this dealership. The one I bought it from is 2 hours away. I hope to get this resolved but I have a bad feeling that I'm going to get the runaround. Wish me luck!

 

[WalleyeMikeIII]

Thank You Dave,

Thanks again for taking the time to respond. I have an appointment to bring in the vehicle to a dealer that is closer to my house. In your opinion, even though I did not buy from this dealership, should they be responsible for a rental of another Yukon while mine is in their shop? I feel kind of weird complaining about things when I didn't buy from this dealership. The one I bought it from is 2 hours away. I hope to get this resolved but I have a bad feeling that I'm going to get the runaround. Wish me luck!

GM Vehicles under warranty that need an overnight stay for service should dictate that the dealer needs to give you a loaner (which they get paid for by GM).

In the current environment of no supply, no dealer should get mad about you not buying from them, as they may not have had one to sell you.

I'd have a covo w/ the service manager, and explain that they have a chance to win you as a long term customer if they perform well...I started a 30 year relationship with a dealer via their service department..