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Does anyone know what the fix is for the shifting issues with the new colorado?

123K views 352 replies 150 participants last post by  agsy 
#1 ·
My brand new Colorado hesitates when going up hill and then kicks in really hard. It has also reved up to 5000 rps going downhill and feeling like it is stuck in first gear on me two different times. I have read several posts about this topic, but i have not found the solution to it. I have heard that it is normal and the vehicle adapts to you over time. blah blah blah. The point is that it is very annoying and when you spend 40,000.00 on a vehicle you would think that it would shift smoothly. Has anyone got any answers from GM. Im trying to decided if i need to take it in, but i want to make sure its a problem first.
 
#2 ·
Definitely take it in. If it really is an issue, GM needs to get the feedback. If one or two people complain, that's one thing, but if they receive a significant amount of negative feedback through their dealer network, maybe they will be more likely to make a change.
 
#5 ·
I have heard about the trifecta tune, but not sure what it does exactly. I think gm should realize it is a problem. People all over this Forum have been having the same issue.
 
#8 ·
Next time you take it out give it a couple of hard accelerations to re-educate the transmission. Early on, I assumed that "learning transmission," meant it adopted to your driving style over a period of time and set itself to match and that was that, but it actually seems to pick up pretty quickly how you want it behave at any given time. If I drive easy for a few miles it slows the downshifts right away and if I kick it hard a couple of times it promptly starts shifting in a sportier way.
 
#9 ·
Thank you steve! Very helpful information. I almost have 1000 miles on it. I wonder if it will eventually not do that anymore?
 
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#24 ·
16k here and it's as bad as ever!
 
#12 ·
It has also reved up to 5000 rps going downhill and feeling like it is stuck in first gear on me two different times
Do you have hill decent control turned on? If it is, the transmission will downshift to grade brake down hills.
 
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#13 ·
Hill Descent is only operational at low speeds, below 20 MPH, from the owner's manual:

When enabled, if the vehicle is at a
speed above 30 km/h (19 mph) and
less than 60 km/h (37 mph), a DIC
message will display instructing the
driver to reduce speed for HDC
operation.
 
#16 ·
I just keep my Diablo in the glovebox. All I need is a few minutes and a good battery to have a "stock" vehicle again. Put it in my pocket when the wrecker comes.
 
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#17 ·
Move on.

We're done with tune and warranty talk.

A consumer who modifies their truck computer assumes the responsibility of potentially voiding warranty for things affected by said work. They understand that risk at the time of tune, and is no need for a discussion here (as I previously stated).

Any other comments back and forth about 'stupid truck owners' will be deleted.
 
#18 ·
OK, so you don't trust the tune...no problem but you will have to live with the transmission foibles then. The tune on these trucks needs work but in my opinion GM will take their time addressing it, if ever. Yes it does get slightly better as you drive it but it will never be right until GM realizes it has issues and does something about it. You can take it to the dealer but I'll bet my months wages (not a big gambler) they say it is normal and nothing will be done. It doesn't hurt to complain and maybe it will actually make it to someone that matters but again I doubt it. GM cares about their fuel mileage numbers and that's it, they've never been very good at listening to customers on these types of issues.

The Trifecta tune does wonders for the driveability of these trucks, the tranny shifts like it should and the truck has plenty of power and responsiveness. I understand the warranty problems but to me it is worth the risk, besides even if they knew about the tune they have to prove IT caused the breakage in order to void the warranty and then it would only void that which they could prove it caused but enough of that, I don't want to get scolded ;) Currently Trifecta is still offering a trial tune that only limits the max speed to 87 mph, I decided to try it and I'm sold on it but to each their own. I hope for everyone GM gets it together and comes out with a better tune but.....well time will tell.
 
#29 · (Edited)
Just flipped over 1400 miles and the "downshift issue" is completely gone. I guess I "educated" the truck when I stopped treating it like a fragile Lladro and about 100 miles back started whipping its ass with the accelerator.

Separate issue, but I was also getting horrible city mileage, hand calculated at 13-14. Then I read something about how running the AC can potentially lower mpg by 30%. Also, living in constantly congested Fort Lauderdale might have something to do with it. A 3-mile trip here can sometimes take 25 minutes - arrrrggghhhh! Anyway, those 2 things might be factors in the low city mpg I've been getting. But last week I drove round-trip to Delray Beach (about 80 miles total) on the FL Turnpike with very little traffic, and averaged 27.5 mpg maintaining ~70-75 mph with the cruise on. This made me smile.
 
#23 ·
My tranny was naive at first but it acquired an education over time....took about 500-600 miles. I think it had to do with the fact I wasn't reluctant to give it a kick in the a** on occasion like a jockey going for the triple crown. I also believe using the cruise control very frequently and letting it seek its own shift pattern based on ECU/tranny programmed variables w/o my throttle input assisted in its rapid education. It shifts 100% perfectly and is a joy to drive. I can't say it was when it was a virgin on the first 500 mile honeymoon right after delivery. Practice always makes perfect.
 
#26 ·
The electronic brain for the tranny in my '15 Colorado definitely is missing some brain cells. Seemed to be adapting to my driving for a while, then it began to aggressively downshift descending highway grades then not up-shifting when I get back on the gas. Annoying. Service said "Normal behavior." Yeah.
 
#27 ·
Trifecta tune improved my MPG, acceleration, responsiveness, and overall driving experience. I was surprised as **** when it was done. **** thing feels like a V8 sometimes.

However, it still hiccups on inclines. Downward shifting, RPMs drop. Its waiting on me to step on it when it happens; just a really more excited engine now.

Anyway, I feel like you're robbing yourself by not trying out their demo. Its free. And totally worth it. Who knows how long they'll offer it. If it gives you any peace, I've sent in my truck three times to the dealer with the tune. They haven't said **** yet (knock on wood).
 
#31 ·
I also am having issues with going downhill and the tranny downshifts, reving the engine to 5000 +. It seems to happen only when we're in the mountains at higher elevation. I have 4000 miles and have used the cruse control on many occasions but rarely drive the truck like I stole it. If this is normal something is wrong with GM's idea of normal
 
#32 ·
The aggressive driving works on mine it will downshift as long as I am aggressive. Talked with dealer on first oil change. Transmission is there biggest complaint, said not to let wife dive truck seems two days an it looses your pattern and has a new pattern. Seems customers even with the big trucks come saying transmission is broken after someone else has driven the vehicle. I guess that's why after a couple of days I have to go back to aggressive driving or it chugs up my hill in 5th gear at 20 mph. Sometimes Smart is not smarter. Never bought a vehicle with a dumb transmission that would not downshift when you were going 20 mph.
I have read this may not be a GM transmission so maybe they can't fix it, if they didn't write the contract with the right clauses.
Still think it's a great truck.
 
#34 ·
I have read this may not be a GM transmission

this trans is without a doubt built by GM, all of the GM and Ford 6speeds (exception being the Allison) were born from a colabrative effort between the two, but each company produces the transmission they use for themselves.
 
#35 ·
Perhaps the fact that I live in what a bicycle rider would consider a somewhat hilly neighborhood I can get scored in the satisfied group. Will admit it was a bit sluggish early on going up hills, and then would drop 2-3 gears with a big lurch when trying to accelerate. After a few hundred miles it drives as I would expect, and despite some suggesting that letting the wife drive a couple of days or driving real easy causes a need to learn all over.....sorry but I have to respectfully disagree, it just doesn't reprogram that fast. Where once considered the Trifecta/Diablo tune I'm not in any rush. Always like more HP/Torque but I want to make sure that even the tuners have worked out all the bugs. It's sad to hear that some can't find the satisfaction they want.....because of mine and others here we know it's possible for the trans to learn so does it just come down to how one operates their vehicle?
 
#36 ·
I have had zero issues with the transmission in my truck... It is the best working auto I have ever owned... A perfect match to the LFX !!! Hope those that are having issues get it fixed !!!
 
#37 ·
I thought the trans in my Colorado had finally learned my driving style. Shifts were nice for about 1K, then I took a 200 mile trip at a fairly leasurley pace, excepprt for passing several slowpokes. Now it's back to being confused when I want a downshift. Drops two gears,goes up two gears, then settles on the middle gear. GM must use "Common Core Math" for the shift algorithms, which would explain why the dang thing gets confused.
 
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#38 ·
Question: I live in Western PA (Pittsburgh) and driving here is like driving in an escher painting . . . lots of nonsensical, violent turns and drop offs. Anywho, I drive up and down steep hills at low speeds pretty much like always. After driving the truck for its first week, I've started manually shifting usually from 2nd into 3rd gear when going down steep hills.

Here's the question: By manually shifting when driving downhill, am I still 'educating' the truck's transmission? Should I stop doing this? Is the alternative to then accelerate downhill while in a lower gear? 'cause that just feels wrong.

Thanks!
 
#39 ·
the trans is not going to learn if you are manually shifting. if you don't want the trans to go above 3rd gear, you can set it to M3 and leave it there, it will shift automatically between 1-2-3 and learn those shifts.
 
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