2017 GMC Sierra 1500 2WD 6 speed transmission failure

08 GMC · May 22, 2020

So I have 70k miles and the transmission lost 1 and 4 gear. Has a 6 speed

dealer will not fix it for less than $5K. Code said torque converter was bad but now the dealer cannot find any codes. Says pay us $1k to open it up and then repairs past that.

anyone else with a bad transmission ??

ToxicFire · May 23, 2020

Is the 6 speed trans a common thing to have issues?
I'm looking at a 17 Sierra with 50k miles but all the dang issues we have been having with our gm vehicles over last 2 years is some bad luck lol.

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08 GMC · May 23, 2020

????

the dealer smells blood so they are a last resort. I was wondering if a salvage yard has a good one.

Eddie 70 · May 23, 2020

I am at 110k miles on my 14 with the 6 speed. My first fluid and filter change was at 60kish. The fluid looked bad. Ever since then, every 15k miles, I have pulled 1 gallon of fluid out the dipstick and replaced it with a new gallon of fluid. My fluid has looked like new ever since then and my trucks transmission seems to be doing fine. It may go tomorrow but I for one will continue my maintenance schedule.

flyingfool · May 23, 2020

On 5/22/2020 at 12:05 AM, 08 GMC said:

So I have 70k miles and the transmission lost 1 and 4 gear. Has a 6 speed

dealer will not fix it for less than $5K. Code said torque converter was bad but now the dealer cannot find any codes. Says pay us $1k to open it up and then repairs past that.

anyone else with a bad transmission ??

take it to a transmission shop who knows the GM tranny. the TECEM might need to be over-hauled and checked for leaks in the valve system or the thin check films might be torn, you can do this in your garage at home

Edited May 23, 2020 by flyingfool

08 GMC · May 24, 2020

What is a budget for a repair shop?

would it be cheaper to get one from a junk yard??

WilliamBos · May 24, 2020

Take it to a trans shop if you have no warranty. You are rolling the dice on a scrap yard trans.

tlaw91 · May 25, 2020

I make money on 6 speeds...they explode a lot....

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flyingfool · May 25, 2020

a trans shop isnt neccessary, any competant mechanic can pull the Tecm and slap in an ovehaul kit. if it drives then your clutches are probably fine. i wouldnt spend more than $300/400 on a quick overhaul on the switches and seals in the valvebody just to see if it corrects the issue.

Edited May 25, 2020 by flyingfool

tlaw91 · May 25, 2020

Torque converter shudders

Causes the pump vane to shudder and dig into the case

Causes medal to go everywhere

Needs converter, torque converter housing, pump, valve body, techm, filter usually some steels and fibers, normally the 1-2-3-4 and 3-5-R clutches.

I just get the 1-2-3-4 clutch assembly because it’s already built and I’m the laziest.

Now you know!

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flyingfool · May 25, 2020

good info, how glittery is the oil on a bad trans from what you've seen.?

I wonder what the TC lock up data looks like on a good trans vs one that shudders

Edited May 25, 2020 by flyingfool

tlaw91 · May 25, 2020

TC lockup percentage will stay the same.

If you graph slip speed you can see it but we use the PICOscope and measure vibrations then based on the T vibration determine shudder

However you don’t feel it really so people don’t come in for it. They come in because transmission no worky

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Colossus · May 26, 2020

Don't deal with the stealership if you are out of warranty. There will be great transmission shops out there you just need to do your research and find them.

Colossus · May 26, 2020

A good tranny shop will rebuild for much less than $3000 and will add and use componants that are more bulletproof vs what is in there now. Flush the tranny every 15,000-30,000 miles depending on what type of driving you are doing. I am a firm believer in tranny flushes IF they are done properly and at the right times. They will always be more beneficial than a drain and fill. And they will NOT cause premature failure on a tranny that is not already on its way out. Now.. if the fluid is already burnt and in bad shape, the tranny damage is done. take your chances with a flush or do a drain and fill but if the fluid is still in decent shape a flush and good tranny additive will do a great job.

flyingfool · May 26, 2020

3 hours ago, Colossus said:

A good tranny shop will rebuild for much less than $3000 and will add and use componants that are more bulletproof vs what is in there now. Flush the tranny every 15,000-30,000 miles depending on what type of driving you are doing. I am a firm believer in tranny flushes IF they are done properly and at the right times. They will always be more beneficial than a drain and fill. And they will NOT cause premature failure on a tranny that is not already on its way out. Now.. if the fluid is already burnt and in bad shape, the tranny damage is done. take your chances with a flush or do a drain and fill but if the fluid is still in decent shape a flush and good tranny additive will do a great job.

not sure if flushing will solve the issue, like tlaw91 says if the OEM TC is poorly built, and causing damage the pump over time , your stuff is toast no matter how much you flush it. just need to get better parts from Circle-D or elsewhere