2007 Yukon Denali XL Transmission Failure

[2007 Denali XL]

Hi,

I am trying to diagnose this transmission issue and would welcome any advice or pointing to other threads with the same issues.

Symptoms.

Driving on Freeway and noticed that the car was having what I think was slippage when accelerating. Got to my destination and left the car for a few hours. On the return journey the slipping worsened and then lost all gears and check engine light came one (engine running fine)

After about 20mins on the side of the freeway cooling down I started it up and I got 1st and reverse back, but had the car towed to garage.

Mechanic had the car for 3 days could not recreate the issue and said the car was running well. I drove the car home and once the transmission got up to temp the issue started again and broke down in the same way as before. I can leave the car to cool down and I get the gears working again but then loose them and now no gears are engaging at all or for only a minute after a restart.

the codes 2723, 0700, 0796, 2714 are being reported by my basic Innova 1303 which are all related to transmission solenoids and transmission.

There is a slight sheering noise coming from the trans pan area, it's faint but I can notice it.

Any help would be greatly welcomed.

 

[wjburken]

Hi,

I am trying to diagnose this transmission issue and would welcome any advice or pointing to other threads with the same issues.

Symptoms.

Driving on Freeway and noticed that the car was having what I think was slippage when accelerating. Got to my destination and left the car for a few hours. On the return journey the slipping worsened and then lost all gears and check engine light came one (engine running fine)

After about 20mins on the side of the freeway cooling down I started it up and I got 1st and reverse back, but had the car towed to garage.

Mechanic had the car for 3 days could not recreate the issue and said the car was running well. I drove the car home and once the transmission got up to temp the issue started again and broke down in the same way as before. I can leave the car to cool down and I get the gears working again but then loose them and now no gears are engaging at all or for only a minute after a restart.

the codes 2723, 0700, 0796, 2714 are being reported by my basic Innova 1303 which are all related to transmission solenoids and transmission.

There is a slight sheering noise coming from the trans pan area, it's faint but I can notice it.

Any help would be greatly welcomed.

Let’s start with the basics.

How many miles on the vehicle?
How many miles on transmission?
When was last time transmission fluid was changed?
What does the transmission fluid look like? Smell like?

If the mechanic you took it to can’t recreate the issue, I would take it to a shop that specializes in transmissions and have them look at it.

I put a reman transmission in my 2007 Denali XL at 160K. It’s not uncommon for these vehicles to have transmission issues. Sometimes a few targeted parts is all they need. Sometimes a full rebuild or replace is called for.

 

[OR VietVet]

So the tech could not duplicate but did not pay attention to these codes? I can only assume you checked fluid level as described in your manual. Did you? Did the tech? Basics first. You also gave no mileage or engine size. 5.3, 6.0, 6.2? I think those are the options. Help us help you.

Condition of the fluid.....color?


Last time any trans repairs or maint done? Last time any other repair or maint work was done?

Welcome to the forum from Oregon.


After I posted this, I saw Wade beat me to it. I am old ya know.

 

[wjburken]

So the tech could not duplicate but did not pay attention to these codes? I can only assume you checked fluid level as described in your manual. Did you? Did the tech? Basics first. You also gave no mileage or engine size. 5.3, 6.0, 6.2? I think those are the options. Help us help you.

Condition of the fluid.....color?


Last time any trans repairs or maint done? Last time any other repair or maint work was done?

Welcome to the forum from Oregon.


After I posted this, I saw Wade beat me to it. I am old ya know.

For engine size, the 2007 Denali has a 6.2L with a 6 speed transmission.

 

[swathdiver]

Hi,

I am trying to diagnose this transmission issue and would welcome any advice or pointing to other threads with the same issues.

Symptoms.

Driving on Freeway and noticed that the car was having what I think was slippage when accelerating. Got to my destination and left the car for a few hours. On the return journey the slipping worsened and then lost all gears and check engine light came one (engine running fine)

After about 20mins on the side of the freeway cooling down I started it up and I got 1st and reverse back, but had the car towed to garage.

Mechanic had the car for 3 days could not recreate the issue and said the car was running well. I drove the car home and once the transmission got up to temp the issue started again and broke down in the same way as before. I can leave the car to cool down and I get the gears working again but then loose them and now no gears are engaging at all or for only a minute after a restart.

the codes 2723, 0700, 0796, 2714 are being reported by my basic Innova 1303 which are all related to transmission solenoids and transmission.

There is a slight sheering noise coming from the trans pan area, it's faint but I can notice it.

Any help would be greatly welcomed.

A mechanic with a Tech-2 can run the program that attempts to unstick these solenoids. Your fluid is probably dirty and affecting their operation and or they are wore out. You can rebuild the solenoids yourself without removing the transmission for about $90 plus fluids. Several guys on here did last year and the year before as I recall with excellent results.

You can get the parts off Amazon and fix it on your kitchen table.

https://www.amazon.com/dp/B072C63HM...olid=1O8HYKQGI11MB&psc=1&ref_=lv_vv_lig_dp_it



After the repair, have someone or you, run the Service Fast Learn Adapts procedure with the Tech-2.

 

[swathdiver]

Sometimes that P0796 is the result of the filter getting loose or damaged.

If this were mine, I'd first check the fluid level, then the pressure via the Tech-2. Then run the Control Solenoid Valve and Transmission Control Module Assembly Cleaning and test drive again after clearing the codes.

Then run the Performance Test and if it then looks like the solenoids, I'd rebuild them and then do the Service Fast Learn Adapts and take it from there.

Of course, a new filter and replacing all of the fluid would be the done as well.

 

[2007 Denali XL]

Let’s start with the basics.

How many miles on the vehicle?
How many miles on transmission?
When was last time transmission fluid was changed?
What does the transmission fluid look like? Smell like?

If the mechanic you took it to can’t recreate the issue, I would take it to a shop that specializes in transmissions and have them look at it.

I put a reman transmission in my 2007 Denali XL at 160K. It’s not uncommon for these vehicles to have transmission issues. Sometimes a few targeted parts is all they need. Sometimes a full rebuild or replace is called for.

test

 

[2007 Denali XL]

test

thanks,

147K Miles
147k On the transmission
Unknown when the fluid was changed
Fluid is red or pinkish, will smell it and check back

 

[2007 Denali XL]

So the tech could not duplicate but did not pay attention to these codes? I can only assume you checked fluid level as described in your manual. Did you? Did the tech? Basics first. You also gave no mileage or engine size. 5.3, 6.0, 6.2? I think those are the options. Help us help you.

Condition of the fluid.....color?


Last time any trans repairs or maint done? Last time any other repair or maint work was done?

Welcome to the forum from Oregon.


After I posted this, I saw Wade beat me to it. I am old ya know.

thanks for replying.

The Tech thinks that a mouse has been at the wiring loom and is giving false positives but I think that is nonsense.

Fluid is pinkish and levels are correct

 

[2007 Denali XL]

Sometimes that P0796 is the result of the filter getting loose or damaged.

If this were mine, I'd first check the fluid level, then the pressure via the Tech-2. Then run the Control Solenoid Valve and Transmission Control Module Assembly Cleaning and test drive again after clearing the codes.

Then run the Performance Test and if it then looks like the solenoids, I'd rebuild them and then do the Service Fast Learn Adapts and take it from there.

Of course, a new filter and replacing all of the fluid would be the done as well.

Can you send me a link to a "tech 2" please