2017 Yukon P0700/P0796/P2723

[solson96]

My wife called and said her Yukon is driving. I showed up and it would not go into any gear. I turned it off and started it up and it would drive....for a little while it would slip and then rev up so I pulled over. Until this point no codes. I Sat on the freeway and didn't want to leave it b/c the windows would have been busted, and it's 100 degrees in Texas. Long story short I had to do this until I got home 8 miles away, each time getting farther on the freeway. About 3 miles from the house it finally had the check engine light come on and it threw those codes. Several months ago I took it to the Cadillac dealership in Dallas to have the tranny fluid changed at 75k miles. It only has 79k and it's 2017. Any thoughts, it's never been dogged or driven hard. I am going to cry if it's a blown tranny....totally not in the mood to make a joke about blown tranny's.

 

[solson96]

My wife called and said her Yukon is driving. I showed up and it would not go into any gear. I turned it off and started it up and it would drive....for a little while it would slip and then rev up so I pulled over. Until this point no codes. I Sat on the freeway and didn't want to leave it b/c the windows would have been busted, and it's 100 degrees in Texas. Long story short I had to do this until I got home 8 miles away, each time getting farther on the freeway. About 3 miles from the house it finally had the check engine light come on and it threw those codes. Several months ago I took it to the Cadillac dealership in Dallas to have the tranny fluid changed at 75k miles. It only has 79k and it's 2017. Any thoughts, it's never been dogged or driven hard. I am going to cry if it's a blown tranny....totally not in the mood to make a joke about blown tranny's.

Also forgot to add I checked the fluid ans it’s at the perfect level and looks brand new as it should being two months old!

 

[Tahoe14]

Maybe @NickTransmissions will chime in with some assistance.

 

[NickTransmissions]

I am going to cry if it's a blown tranny....totally not in the mood to make a joke about blown tranny's.

Also forgot to add I checked the fluid and it’s at the perfect level and looks brand new as it should being two months old!

Blown trannies -no laughing matter at all (lol!).

This is likely either TEHCM or valve body....

P0700 is a general transmission control module fault/failure code (in 6L transmissions, the TCM is referred to as the transmission electronic hydraulic control model or TEHCM for short) while P0796 and P02723 are solenoid performance codes (stuck on/off) but can indicate problems with the valve body as well as the TEHCM. P0796 refers to clutch pressure control solenoid #3 is stuck in the 'off' position while P2723 is telling you that clutch pressure control solenoid #5 is stuck off. Both of these solenoids are 'on' in first, second and third gear while CPC #3 comes off in fourth gear (CPC#5 is on in gears 1-4). So if CPC# 3 and 5 are stuck off, you'll have no forward movement.

P0796 can also indicate a sticking/stuck CBR1/4-5-6 regulator valve (upper valve body) while P2723 can indicate a stuck 1-2-3-4 clutch regulator valve (if this valve is stuck in the 'off' position, you won't move forward).

Next steps
Drop the control body complex from the transmission and separate the TECHM from the valve body. Take a multi-meter and start ohm'ing out all of your solenoids (see page one of my 6L80 transmission info thread for instructions on how to do this). Then test your pressure switches (same thread for reference). Take note of the part number on the TEHCM that begins with '242' as it's critically important that, if you end up having to replace the TEHCM, you get one with the same part number (or ensure the remanufactured TEHCM is programmed with the same operating system installed onto your vehicle's ECM).

If the TEHCM passes all tests, move to the valve body and separate the two halves by withdrawing the remaining bolts from the TEHCM side and all 12 7mm bolts from the speed sensor/harness side and begin stroking the valves in both halves with a small flat blade screw driver to see if any are stuck. If no stuck valves (or dragging valves) are noted, then the cause is likely a cracked 1-2-3-4 piston inside the 3-5-R drum inside the case and if so, time for a rebuild (may also be torque converter as these converters commonly fail for a variety of reasons).

Side Note for All
Checking the fluid at the dipstick actually tells you very little about what's going on inside the transmission (other than the level itself and checked while vehicle is at op temp), unless you drop the pan or it's absolutely filthy, by which point you won't need to check the dipstick to know the transmission is smoked.

Quote this post or mention me (@NickTransmissions ) if you reply back to this thread with any questions for me so that I know you have responded. Otherwise I don't get alerts if you simply respond w/a new post without doing one or the other.

 

[solson96]

Blown trannies -no laughing matter at all (lol!).

This is likely either TEHCM or valve body....

P0700 is a general transmission control module fault/failure code (in 6L transmissions, the TCM is referred to as the transmission electronic hydraulic control model or TEHCM for short) while P0796 and P02723 are solenoid performance codes (stuck on/off) but can indicate problems with the valve body as well as the TEHCM. P0796 refers to clutch pressure control solenoid #3 is stuck in the 'off' position while P2723 is telling you that clutch pressure control solenoid #5 is stuck off. Both of these solenoids are 'on' in first, second and third gear while CPC #3 comes off in fourth gear (CPC#5 is on in gears 1-4). So if CPC# 3 and 5 are stuck off, you'll have no forward movement.

P0796 can also indicate a sticking/stuck CBR1/4-5-6 regulator valve (upper valve body) while P2723 can indicate a stuck 1-2-3-4 clutch regulator valve (if this valve is stuck in the 'off' position, you won't move forward).

Next steps
Drop the control body complex from the transmission and separate the TECHM from the valve body. Take a multi-meter and start ohm'ing out all of your solenoids (see page one of my 6L80 transmission info thread for instructions on how to do this). Then test your pressure switches (same thread for reference). Take note of the part number on the TEHCM that begins with '242' as it's critically important that, if you end up having to replace the TEHCM, you get one with the same part number (or ensure the remanufactured TEHCM is programmed with the same operating system installed onto your vehicle's ECM).

If the TEHCM passes all tests, move to the valve body and separate the two halves by withdrawing the remaining bolts from the TEHCM side and all 12 7mm bolts from the speed sensor/harness side and begin stroking the valves in both halves with a small flat blade screw driver to see if any are stuck. If no stuck valves (or dragging valves) are noted, then the cause is likely a cracked 1-2-3-4 piston inside the 3-5-R drum inside the case and if so, time for a rebuild (may also be torque converter as these converters commonly fail for a variety of reasons).

Side Note for All
Checking the fluid at the dipstick actually tells you very little about what's going on inside the transmission (other than the level itself and checked while vehicle is at op temp), unless you drop the pan or it's absolutely filthy, by which point you won't need to check the dipstick to know the transmission is smoked.

Quote this post or mention me (@NickTransmissions ) if you reply back to this thread with any questions for me so that I know you have responded. Otherwise I don't get alerts if you simply respond w/a new post without doing one or the other.

Awesome thank you Ill grab my meter and hit it in the morning!!! Don't need to spend money on a new transmission, wife will have to strip in the evenings lol

 

[NickTransmissions]

Awesome thank you Ill grab my meter and hit it in the morning!!! Don't need to spend money on a new transmission, wife will have to strip in the evenings lol

Yep, don't want to have to resort to such measures...let me know what the fluid looks like, matter in the pan and results of your tests. Check the filter for cracks on the neck as well - cracks there can throw solenoid performance codes and produce no movement conditions as well.

 

[marcellaann91]

My wife called and said her Yukon is driving. I showed up and it would not go into any gear. I turned it off and started it up and it would drive....for a little while it would slip and then rev up so I pulled over. Until this point no codes. I Sat on the freeway and didn't want to leave it b/c the windows would have been busted, and it's 100 degrees in Texas. Long story short I had to do this until I got home 8 miles away, each time getting farther on the freeway. About 3 miles from the house it finally had the check engine light come on and it threw those codes. Several months ago I took it to the Cadillac dealership in Dallas to have the tranny fluid changed at 75k miles. It only has 79k and it's 2017. Any thoughts, it's never been dogged or driven hard. I am going to cry if it's a blown tranny....totally not in the mood to make a joke about blown tranny's.

Did you ever find out the cause of this? My Yukon is doing the exact same thing.