Transmission Woes :-(

No1UKnow · June 15

Hello All!

My 2019 Colorado 3.6 LT, 4WD Crew Cab has approximately 77,500 miles and I recently began experiencing the well-known transmission shudder between about 30 and 65 mph. The problem had worsened to the point that I could no longer attribute it to road conditions - and I had decided to bring the truck to the dealer - when recently, I experienced a sudden loss of power while driving at maybe 40 MPH. Several warning lights flashed, the “Check Stabilitrack” message appeared, and the Check Engine, Stabilitrack, and Traction Control icons remained illuminated. The truck regained driving power, but it stayed in a low gear with unusually high RPMs for the speed. (limp mode?) Because I was only about two miles from home, driving slowly, I was able to make it back and run an OBD-II scan, which showed fault codes U0101, P0700, and U0100. My next trip in the truck was to drive it to the dealer the following day. That trip began normally, but after about a mile I experienced another loss of power, along with the same warning lights and the same “Check Stabilitrack” message. As before the truck remained driveable, but again operated at an abnormally high RPM-to-speed ratio and seemed stuck in a single gear. About a mile later, the dashboard lit up once more, this time displaying “Check 4WD.” Soon after that, I arrived at the dealer. I have verified that the truck still has its original factory transmission fluid, which means it has never received the corrective fluid exchange outlined in GM Technical Service Bulletin #18-NA-355. That was Thursday of last week and I've heard nothing yet from the dealer.

According to Technical Service Bulletin #18-NA-355 and the build date of my truck, my truck should have the newer LV fluid. I've done a little research and read something about a problem with the wiring harness as well.

Anyone have an insights into this situation? Thank you!!

asilverblazer · June 15

1 hour ago, No1UKnow said:

Hello All!

My 2019 Colorado 3.6 LT, 4WD Crew Cab has approximately 77,500 miles and I recently began experiencing the well-known transmission shudder between about 30 and 65 mph. The problem had worsened to the point that I could no longer attribute it to road conditions - and I had decided to bring the truck to the dealer - when recently, I experienced a sudden loss of power while driving at maybe 40 MPH. Several warning lights flashed, the “Check Stabilitrack” message appeared, and the Check Engine, Stabilitrack, and Traction Control icons remained illuminated. The truck regained driving power, but it stayed in a low gear with unusually high RPMs for the speed. (limp mode?) Because I was only about two miles from home, driving slowly, I was able to make it back and run an OBD-II scan, which showed fault codes U0101, P0700, and U0100. My next trip in the truck was to drive it to the dealer the following day. That trip began normally, but after about a mile I experienced another loss of power, along with the same warning lights and the same “Check Stabilitrack” message. As before the truck remained driveable, but again operated at an abnormally high RPM-to-speed ratio and seemed stuck in a single gear. About a mile later, the dashboard lit up once more, this time displaying “Check 4WD.” Soon after that, I arrived at the dealer. I have verified that the truck still has its original factory transmission fluid, which means it has never received the corrective fluid exchange outlined in GM Technical Service Bulletin #18-NA-355. That was Thursday of last week and I've heard nothing yet from the dealer.

According to Technical Service Bulletin #18-NA-355 and the build date of my truck, my truck should have the newer LV fluid. I've done a little research and read something about a problem with the wiring harness as well.

Anyone have an insights into this situation? Thank you!!

I think it failed, new fluid isn't going to fix it.

No1UKnow · June 15

3 hours ago, asilverblazer said:

I think it failed, new fluid isn't going to fix it.

Thanks. I've read this can happen with a loss of communication with the TCM as well.

newdude · June 16

8 hours ago, No1UKnow said:

Hello All!

My 2019 Colorado 3.6 LT, 4WD Crew Cab has approximately 77,500 miles and I recently began experiencing the well-known transmission shudder between about 30 and 65 mph. The problem had worsened to the point that I could no longer attribute it to road conditions - and I had decided to bring the truck to the dealer - when recently, I experienced a sudden loss of power while driving at maybe 40 MPH. Several warning lights flashed, the “Check Stabilitrack” message appeared, and the Check Engine, Stabilitrack, and Traction Control icons remained illuminated. The truck regained driving power, but it stayed in a low gear with unusually high RPMs for the speed. (limp mode?) Because I was only about two miles from home, driving slowly, I was able to make it back and run an OBD-II scan, which showed fault codes U0101, P0700, and U0100. My next trip in the truck was to drive it to the dealer the following day. That trip began normally, but after about a mile I experienced another loss of power, along with the same warning lights and the same “Check Stabilitrack” message. As before the truck remained driveable, but again operated at an abnormally high RPM-to-speed ratio and seemed stuck in a single gear. About a mile later, the dashboard lit up once more, this time displaying “Check 4WD.” Soon after that, I arrived at the dealer. I have verified that the truck still has its original factory transmission fluid, which means it has never received the corrective fluid exchange outlined in GM Technical Service Bulletin #18-NA-355. That was Thursday of last week and I've heard nothing yet from the dealer.

According to Technical Service Bulletin #18-NA-355 and the build date of my truck, my truck should have the newer LV fluid. I've done a little research and read something about a problem with the wiring harness as well.

Anyone have an insights into this situation? Thank you!!

You need a better code reader/scanner. You are missing codes. Did the dealer give you a copy of the SAVI scan from that visit?

If the fluid hasn't been changed, change it. Shudder will likely go away.

Edited June 16 by newdude

asilverblazer · June 16

13 hours ago, newdude said:

If the fluid hasn't been changed, change it. Shudder will likely go away.

That P0700 and loss of power suggests something significant is amiss to me.

More/other codes may suggest otherwise; I would investigate those prior to spending the money to change fluid on a transmission with a bad torque converter.

The relatively sudden escalation of symptoms to me suggests that something began failing (initial shuddering experienced) and rapidly deteriorated (slipping/loss of power). Fluid condition alone wouldn't cause the sudden escalation of problems - though it might have been the cause of the deterioration up to the point of failure.

No1UKnow · June 16

13 hours ago, newdude said:

You need a better code reader/scanner. You are missing codes. Did the dealer give you a copy of the SAVI scan from that visit?

If the fluid hasn't been changed, change it. Shudder will likely go away.

Thanks!

No1UKnow · June 16

16 minutes ago, asilverblazer said:

That P0700 and loss of power suggests something significant is amiss to me.

More/other codes may suggest otherwise; I would investigate those prior to spending the money to change fluid on a transmission with a bad torque converter.

The relatively sudden escalation of symptoms to me suggests that something began failing (initial shuddering experienced) and rapidly deteriorated (slipping/loss of power). Fluid condition alone wouldn't cause the sudden escalation of problems - though it might have been the cause of the deterioration up to the point of failure.

Thank you 'Blazer. I appreciate you sharing your thoughts and experience.

No1UKnow · June 16

19 hours ago, newdude said:

You need a better code reader/scanner. You are missing codes. Did the dealer give you a copy of the SAVI scan from that visit?

If the fluid hasn't been changed, change it. Shudder will likely go away.

Thanks! I'll ask for that. What's the acronym for?

davester · June 17

google "gm savi scan"

No1UKnow · June 17

19 hours ago, No1UKnow said:

No... They haven't. In fact, they've had my truck fr three business days without providing me with ANY information.

No1UKnow · June 19

Well, I received a message from the dealer...

davester · June 20

ouch to both. $650 for hooking up their computer and hitting a "reset adapts" button is ridiculous.

and I would want to know why they think a new transmission is required besides the manager wanting a bigger bonus this quarter.

No1UKnow · June 20

6 hours ago, davester said:

ouch to both. $650 for hooking up their computer and hitting a "reset adapts" button is ridiculous.

and I would want to know why they think a new transmission is required besides the manager wanting a bigger bonus this quarter.

I wonder as well, why they would send me a text message with links to these suggested procedures totalling over $10,000 without even the slightest hint of how they arrived at these being necessary.

asilverblazer · 2026-06-26T18:37:25Z

$10,000 for a transmission?

Pretty sure I could buy all the parts, tools, and education to rebuild it myself for a quarter of that amount.

or swap it out with a new one...

newdude · 2026-06-26T20:07:48Z

1 hour ago, asilverblazer said:

$10,000 for a transmission?

Pretty sure I could buy all the parts, tools, and education to rebuild it myself for a quarter of that amount.

or swap it out with a new one...

OP's quote is parts and labor. Not just parts.

The # you found isn't the right one. But besides that, the right # is the same price within a couple bucks. $5802.01.

Now, factor in labor and fluids. Book time is 17.1 hours for a Colorado 8 speed. At $200/hr for a dealer average rate, its $3420 just in labor. We are already at $9222. Fluid and other necessary items, there's your $400-500 more.

Also. Your "discounted" transmission. Which is 99% likely quoted off of GM Parts Direct as that's the MSRP I found on their site.

You failed to note the $597 in shipping charges. So we are right back almost to MSRP. $5794. Oh. AND, you better have the $4000 for the core charge which you'd have to pay and get refunded, AND you gotta pay to SHIP THE CORE BACK.

So now you'd have paid MORE to buy that one online yourself, just for the transmission, even after you get your core refunded.

Edited yesterday at 08:16 PM by newdude