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Discussion Starter #1
My Colorado loves to downshift two and sometimes three gears when I press the brake to slow down going down hill, almost like it's stuck in tow/haul mode. It does it whether or not the cruise is on, know it's supposed to in tow/haul mode. Really aggravating watching my rpm' skyrocket to almost 4K when it does it. Never does it on level ground only on hills no matter how slight the grade.
 

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I would bring it in, it seems a sensor is off and not throwing it as an error. If you have a reader I would anticipate a code from your exhaust brake or trailer brake controller. Sorry to hear about your issues please let us know what you/they find!
 

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I'm taking right now for my last free oil change and I am going to ask them about it. Sadly these trucks are so new my dealership doesn't seem to know too much about them like I would hope. We'll see what happens. I'll follow up when I get back.
 

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Okay upon further review there seems to be a feature called Downhill Braking Assist that is engaged whenever the key is turned on, I read my owners manual but must have skipped over that thinking it was part of the tow/haul feature. Had to leave my truck with the dealer because once again they do not have a filter nor oil for the oil change so I will have to wait until this evening to see if I can shut it off like my salesman showed me. You press and hold the tow/haul button down for about 5 seconds and it will shut that feature off, I'm assuming it will have to be done every time I restart the truck.
 

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Discussion Starter #5
The only way to shut it off is to use the manual shift and it's called normal grade braking. Love the truck but hate this "feature".
 

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So the break assist is what was crushing your MPG? Thats insane, I've started to drive w/o my traction control on to see if that makes a difference (none so far). I haven't had mine holding gears under 2nd (0-25mph) and have no complaints. I will try that reset out and see how it rolls!
 

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Feature is called auto grade braking. shouldn't affect your mpg's since the tires are actually turning the motor. its different than tow'haul since the auto grade breaking is more like an engine brake than the turbo brake. it usually only does it when you either hold down the brake relatively hard, or if you continuously hit the brake. I like it because it saves my rotor life but I could see how its annoying.

its not random that it does it going downhill, the truck knows when its climbing, descending, or on level ground. I wouldn't worry about it other than it getting on your nerves
 

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Just found this thread but I guess I'll resurrect it since I am a new owner and also find this feature a little annoying. I don't mind the breaking too much but I do find it hard to get it to come out of brake mode. I think that as soon as I touch the gas, it should recognize I don't want any more braking and automatically upshift. But, I have to touch the gas a couple times usually and then let off the gas to get it to upshift. I understand and appreciate what it's trying to do for me but I don't care for the way it takes control from me. My Toyo Taco had a similar feature that was much more subtle - the downshifting would help some to control the speed but it was nowhere near as severe and noticeable as the Colorado.
 

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Discussion Starter #9
Just found this thread but I guess I'll resurrect it since I am a new owner and also find this feature a little annoying. I don't mind the breaking too much but I do find it hard to get it to come out of brake mode. I think that as soon as I touch the gas, it should recognize I don't want any more braking and automatically upshift. But, I have to touch the gas a couple times usually and then let off the gas to get it to upshift. I understand and appreciate what it's trying to do for me but I don't care for the way it takes control from me. My Toyo Taco had a similar feature that was much more subtle - the downshifting would help some to control the speed but it was nowhere near as severe and noticeable as the Colorado.
I have 34k miles on mine and it still does it, annoys the ever loving piss out me! I toggle the tow/haul switch on and off real fast and it shuts that crap off until I use the brake again of course.
 

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Grade braking shouldn't hurt your mpg because during that process your engine should be in deceleration fuel cut off mode (or 99mpg on instant readout)

Do y'all live where it's super hilly and/or ride the brakes? My truck has only done this two or three times and it was on long hills where I was riding the brakes, normally I just let off and coast so I usually don't get this.

Quit riding the brakes down hills. That's what your truck is trying to tell you. The truck is showing you your bad habits. Let off before the crest of the hill and then you'll slow a little and then pick it back up coasting down. Your mpg will increase, too. Imagine that lol
 

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yup, I live in a hilly area and no, I'm not a brake rider. Let me set the scenario for you Rockcrawler: I am dropping off a mesa and I'll be going 50 mph (not applying brakes and at the legal speed limit) and need to slow to 35 for the first corner, I'll put the brakes on pretty gently for 2-3 seconds and boom, the truck will downshift 2 or 3 gears and as someone said, it'll go up to 4k rpm and then it won't let the speed back up. I come out of the turn and try to reaccelerate a bit and it WILL NOT come out of the lower gears without a lot of messing with the gas pedal. In fact, it won't come out of lower gears until I am all the way down the hill and literally have to accelerate faster than I want to go just to get it to kick back out. Does this sound familiar to others? I feel like the concept is good but the application is too heavy handed. It seems they designed the system to automatically take on 100% (or even 110%??) of the braking using the engine. If it were more like 50-70% then it could be a little more subtle and you'd get the engine braking help but it wouldn't feel like it takes over the whole driving experience and force you to do strange things to cancel it out when it's not helping.
 

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Only when I actually have ours in tow/ haul does it do what you're talking about. But even then, I don't think I have to press the accelerator that hard to get it to upshift. I don't know that ours has ever downshifted multiple times with a short brake application while NOT in tow/ haul. If you let off the accelerator, it will hold onto the gear until it drops below a certain mph and then downshift. Or if you are stopping, then of course it downshifts a little faster as you are stopping faster. But never anything like you all are dealing with.

And you have taken it into the dealer, or plan to, those of you who have this problem? I think I would be. See if they can't reset the logic on it to new or factory, so that way the ECM and TCM are in a new learning mode (fast learn) and lets them adapt quickly to how you drive. Hopefully that would fix it. After it got used to your driving, it would at some point switch over to slow learn and keep adapting but at a slower rate. Just weird though.
 

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Hmmmm Burgess, you got me thinking. I put about 1500 miles on when truck was new with minot towing episodes thrown in and then hauled a fairly heavy trailer 1300 miles home. I did not use the tow/haul mode but I'm wondering if the truck "learned" the amount of engine braking it needed to sow down the truck/trailer and it's kind of stayed in that mode? Without a reset, will it slowly relearn and recalibrate to truck only?
 

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Hills of Kentucky. Mine does it too. I'm curious if a tune would take it out
 

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Hills of Kentucky. Mine does it too. I'm curious if a tune would take it out
It might, DeeK. I could see it picking up something like that when it was brand new and still in fast learn. Now, I don't know how long a time/ miles that fast learn stays activated, but being that early in the life of the truck, I could see it learning that if you had a heavy trailer on it and went a long distance. Getting a dealer to reset it to start fresh very well may help you out.

Hills of Kentucky. Mine does it too. I'm curious if a tune would take it out
A tune should yes, Pergrem. I mean, back to the fast/ slow learn on the ECM and TCM like I mentioned above; when I tuned my 2004 Duramax from DuramaxTuner, it told me in the directions that after installing the new tunes on the truck, the ECM and TCM would be in a state of fast learn, so you were to drive the truck in each of the 5 tune modes (optimized stock, light tow, heavy tow, sport economy and race and I believe you did NOT turn tow/ haul on during this) at like 2/3 throttle for a couple minutes each to get it used to each one, then you could put it on whatever mode you wanted and drive the vehicle as you normally would.

You might call the tuner you are considering and ask them what they think, but based on that past experience, I would say yes.
 

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It seems like mine didn’t start doing the grade braking thing until there was 250-300 miles on the odometer. Maybe it’s taking a break-in period into account? Regardless, I’ve experienced it in my work van and it’s an annoying feature. It looks like it can’t be disabled in the Colorado either, short of going into manual mode. I’ll try toggling in and out of tow/haul mode like Sappergod mentioned next time I catch it.
My 2013 Express van does it too and is even more obnoxious, it will drop two gears on every exit ramp if I let it. It must be a six speed transmission thing (even though they aren’t ecactly the same). At least it can be turned off in the Express by holding the tow/haul button for about five seconds. It has to be done every time the engine is started though. I’ve made it a habit to turn it off unless I know I’ll driving on a pan flat route (pretty rare in east Tennessee).
Engine braking has its place but this takes it a little too far. I’m ok with replacing pads and rotors a little more often. I love my truck and I’ll live with this quirk but if there’s a way to have it turned off by default then I’d do it in a heartbeat.
 

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When I know a downhill is coming up I just shift to Manual and control top gear w/ the +/- button. I'd rather control my gear than let the truck decide anyway. No sweat, it's second nature now.
 

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I can't say I've ever had an issue with ours going into tow/ haul randomly. Or down shifting randomly either. 30,000 miles on the truck in not quite a year. We have some decent sized hills near the house here where I'm at in Missouri and I'll leave the cruise on going through them. Most the time, the truck doesn't shift down going up them, it powers through the hill. Going down some, if it gets 2 mph over the cruise it will down shift to slow us down.

Other than that, no issues at all. And that's not really even an issue.
 

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Ours does it when going down a grade, but not that often. Tech. told me when I had mentioned it to him, that the vehicle "learns" your driving habits and the ECM creates some kind-of "memory"?? Don't know if it's B.S. or what though.:rolleyes: MADMAC
 
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