“Service transmission Now, unable to shift soon” message on 2021 Tahoe

[BigE_In_TX]

Full transparency, I have never worked on or even physically seen one of the 10L transmissions as of yet so dont know a whole lot about them.

I did find a TSB on that error/warning message though it applies to Buicks but may be similar in terms of general pattern causes in the truck/SUV chassis.

Also found this GEARS Magazine article on the front-wheel drive equivalent to the rear/AWD longitudional 10 speeds which may be describing the same kind of problem (solenoids/valve body).

Here's what the article says about that specific DIC message:

Service Transmission Now, Unable to Shift Soon
The “Service Transmission Now, Unable to Shift Soon” message indicates that one or more ETRS system faults have occurred. It is a warning to get the vehicle into the shop for service immediately, or it may shortly leave you unable to engage the selected range

I'd call and make an appt and maybe even have it towed to the dealer, esp if the thing could just drop dead at any time, which seems to the case with that message.

Dealer Svc will likely replace solenoids or do a valve body swap after diagnosis.

If you're DYI you can purchase a diagnostic subscription from GM's on-line texh portal, buy whatever laptop-OBD2 cable you need and see what's up with it. Then follow the procedures for parts repair/replacement and reinstallation.

@NickTransmissions Thank you for digging that information up. Very helpful. Maybe it is some sort of update needed?

You know, the darndest thing is, started it this morning and message did not pop up.

Is there any truth to this so called adaptive driving that it learns from your normal habits and environment, so if it is typically a warm weather climate where you live, and BAM all of a sudden it drops to 10-15 degrees, it freaks out?

 

[WalleyeMikeIII]

@NickTransmissions Thank you for digging that information up. Very helpful. Maybe it is some sort of update needed?

You know, the darndest thing is, started it this morning and message did not pop up.

Is there any truth to this so called adaptive driving that it learns from your normal habits and environment, so if it is typically a warm weather climate where you live, and BAM all of a sudden it drops to 10-15 degrees, it freaks out?

It does learn your driving; but a temp change should not throw a code…

 

[NickTransmissions]

@NickTransmissions Thank you for digging that information up. Very helpful. Maybe it is some sort of update needed?

You know, the darndest thing is, started it this morning and message did not pop up.

Is there any truth to this so called adaptive driving that it learns from your normal habits and environment, so if it is typically a warm weather climate where you live, and BAM all of a sudden it drops to 10-15 degrees, it freaks out?

A 10-15 degree drop in temp wouldn't trigger that (or any) code in an otherwise completely healthy system...Sounds like intermittent solenoid failure to me but your best bet is to take it in and get it diagnosed to be certain.

 

[BigE_In_TX]

UPDATE: It has been in the high 40’s/ low 50’s here this week, driving like normal with zero code pop ups. Acting like a good hoe. I visited Autozone as I was thinking could this be a battery starting to crap out? Battery tested fine, so I just am stumped. Very very strange that the one day we get temps waaaaay colder than we normally get (it was 10 degrees) and codes are popping up like crazy, and now as it warmed up the last several days, nothing……

 

[BigE_In_TX]

A 10-15 degree drop in temp wouldn't trigger that (or any) code in an otherwise completely healthy system...Sounds like intermittent solenoid failure to me but your best bet is to take it in and get it diagnosed to be certain.

I just read your reply @NickTransmissions and to clarify, it wasn’t just a 10-15 degree drop, it was a 50 degree drop. It was 9-10 degrees when this time of year it’s typically mid to high 40’s into the 50’s. Getting into teens or single digits is very rare here in winter. Now that it’s warmed up, been acting fine, haven’t seen a code pop up.

 

[NickTransmissions]

I just read your reply @NickTransmissions and to clarify, it wasn’t just a 10-15 degree drop, it was a 50 degree drop. It was 9-10 degrees when this time of year it’s typically mid to high 40’s into the 50’s. Getting into teens or single digits is very rare here in winter. Now that it’s warmed up, been acting fine, haven’t seen a code pop up.

That may or may not make a difference, my lack of familiarity of the 10 speeds rears its ugly head, lol...keep an eye on it but think you have an intermittent fault or issue that is presenting when fluid viscosity reaches a certain threshold. That doesnt strike me as normal. Modern Vehicles are designed to operate without issue in sub-zero conditions so you shouldnt be getting that message at all, IMO, regardless of the temp swings.

 

[BigE_In_TX]

That may or may not make a difference, my lack of familiarity of the 10 speeds rears its ugly head, lol...keep an eye on it but think you have an intermittent fault or issue that is presenting when fluid viscosity reaches a certain threshold. That doesnt strike me as normal. Modern Vehicles are designed to operate without issue in sub-zero conditions so you shouldnt be getting that message at all, IMO, regardless of the temp swings.

Thank you for the solid feedback!

 

[BigE_In_TX]

@Ryan 2024 Just to share my post with you, even though i have a 2WD, our issues line up almost perfect