8.0

pretty bad
Typical Repair Cost:
$350
Average Mileage:
22,800 miles
Total Complaints:
4 complaints

Most Common Solutions:

  1. not sure (2 reports)
  2. triple flush and new fluid (2 reports)
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2018 GMC Sierra 1500 transmission problems

transmission problem

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2018 GMC Sierra 1500 Owner Comments

problem #4

Nov 212022

Sierra 1500 SLT 5.3L V8

  • Automatic transmission
  • 25,852 miles

A D V E R T I S E M E N T S

Flush and fill transmission at 25K for shudder and hard shift. Now at 30K same symptoms are coming back. Going to have them look at it at next regular service. Truck has not been abused or used for towing, majority miles are highway.

- Neal G., Wichita, KS, US

problem #3

Aug 012020

Sierra 1500 Denali 6.2L V8 ECOTEC3

  • Automatic transmission
  • 19,133 miles

2018 GMC Sierra Denali - issue first started as a hard shift every once in a while. Then if progressed to every once in a while the shift was so hard I would look in the rear view mirror to see if someone hit me. Now the issue is that the shudder or shaking is so bad you fell it in the whole truck. Smooth roads have not impact on the ride, it seems to be at is worst when you accelerate a bit and the steering wheel bounces all over the place. Then it will subside, it also seems worst after the truck has warmed up a bit, like 15 minutes. I have taken it to the dealer, they claim they can not reproduce... they are just wrong. I has the tires checked out this weekend by a Tire company, they conducted a road Force and balance test on all the wheels. Road Force was good but the balance was off. All corrected as to proper balance, took the truck for a ride down the interstate and well Shudder and shaking is still very much present. Even the tire company Tread Quarters provided me with a Technical Service Bulletin ( #18-NA-355) March 30,2020 on this issue and it is an exact fix to my trucks issue.

I am going back to the dealer and this, no matter what GM lawyers say is a warranty issue, I purchased this truck partly due to the transmission and how smooth it operated and better fuel.

The bulletin claims the issue may be the Torque Converter Clutch (TCC) Shudder. They claim that on the "correction" notice they did not say fix but correction, to have a fluid exchange to HP fluid.

I am going back to the dealer a bit more educated and talk with the Service Manager.

- mikepr, Chesapeake, VA, United States

problem #2

Jan 082020

Sierra 1500 SLT 6.2L

  • Automatic transmission
  • 10,000 miles

I did the standard flush and fill worked for a little while. I took it to independent shop for another flush fill where they told me the Transmissions were junk and needed a converter, It was slipping very badly at this point - I can't drive it 28k miles on a $60k truck and need thousands of dollars in repair that GM won't cover.

- Kevin D., La Place, LA, US

problem #1

Jul 082019

Sierra 1500 SLT 6.2L V8

  • Automatic transmission
  • 36,100 miles

Bought a pre-owned 2018 GMC Sierra 6.2L that ran beautifully at first, around 35k miles the steering wheel started to give a slight brief shudder in cruise control at about 65mph, and shifts a lot less smoother coming from a dead stop 1st-2nd gear. Feels like I'm running over the warning grooves cut into the road along the shoulder. Called the service department at dealership and he says it is out of warranty and will cost me to do a triple flush and refill with new fluid ($200.00) and labor ($150.00) at 36100 miles. You would think GMC being aware of the problem with these transmissions/torque convertors would at least do the initial flush as a courtesy the first time in.

- Eric C., Jonesboro, AR, US

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