2016 2500 HD trans doesn't shift up when towing

John Bar069 · February 2, 2018

If you read Dnt answer, he has it right on the money. When I tow my bass boat, 4250lbs. I do not use tow mode, or transmission will shift down so hard it scares you. This is consider a lite load. When I tow my toy hauler 8900lbs plus toys and fuel, close to 10,000lbs then tow mode works great. I also have been out west and sometimes on the roads you do not even know that you are going up a grade. So if you are going up a grade and the truck feels like it isn't shifting right or motor seems to be working harder than normal, I would guest that you are going up hill like maybe 15 degrees or so.

KARNUT · February 2, 2018

You can’t force a down shift if you’re going to over rev the engine. You can tune a early up shift, the problem is building heat in the transmission.

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SierraHD17 · February 2, 2018

I have found these trucks always annoying in there love to downshift and rev like mad when they don't actually need too... hell a grade will make the truck do it when it's empty with no trailer. But if you mess with it and get it to upshift it has no issue holding the speed without the rpm. I have screwed around with mine tuning wise and it's a bit better. Ideally I would like manual mode to force it to hold the gear you have selected. Maybe some day.

2016HD · February 3, 2018

12 hours ago, SierraHD17 said:

I have found these trucks always annoying in there love to downshift and rev like mad when they don't actually need too... hell a grade will make the truck do it when it's empty with no trailer. But if you mess with it and get it to upshift it has no issue holding the speed without the rpm. I have screwed around with mine tuning wise and it's a bit better. Ideally I would like manual mode to force it to hold the gear you have selected. Maybe some day.

Even though the engine and trans combo will hold a certain gear under a light load. Does not mean that it is in the correct rpm range for the engine. Lugging an engine is actually worse than having it run at a higher rpm. Hook up and watch a vacuum gauge while doing this. A lot of time you will find that a higher gear and lower rpm will actually cause a lower vacuum reading. This in turn causes a higher fuel usage and more load than is needed. A smaller cubic inch gas engine is better suited for higher rpm work. It will do its best work at or slightly above peak torque. 6.0 is around 4500rpm.. It will pull and tow its best around 4500-5000rpm while heavily loaded up hills etc. For best fuel mileage you are best to see the highest vacuum readings with the least amount of throttle applied. Example small hill the truck shifts down a gear like you stated! it does this because even though it could hold the taller/higher gear. It is not working as hard in the next lower gear and actually using less fuel to do it. Just my 2cs

SierraHD17 · February 3, 2018

5 hours ago, 2016HD said:

Even though the engine and trans combo will hold a certain gear under a light load. Does not mean that it is in the correct rpm range for the engine. Lugging an engine is actually worse than having it run at a higher rpm. Hook up and watch a vacuum gauge while doing this. A lot of time you will find that a higher gear and lower rpm will actually cause a lower vacuum reading. This in turn causes a higher fuel usage and more load than is needed. A smaller cubic inch gas engine is better suited for higher rpm work. It will do its best work at or slightly above peak torque. 6.0 is around 4500rpm.. It will pull and tow its best around 4500-5000rpm while heavily loaded up hills etc. For best fuel mileage you are best to see the highest vacuum readings with the least amount of throttle applied. Example small hill the truck shifts down a gear like you stated! it does this because even though it could hold the taller/higher gear. It is not working as hard in the next lower gear and actually using less fuel to do it. Just my 2cs

I don't really care nor do I want to listen to the thing at 4500 plus rpm when it comfortably does the pull at 2500 rpm. It's not harder on it and fuel economy in one of these HD heaps is irrelevant. Considering I said "empty" That has zero to do with heavily loaded. Even when loaded if I can make it stay in the higher gear (can't have it panned here or it's downshifting) and it pulls the grade easily there is no need to listen to it screaming away for nothing. I have been screwing with this junk both building and tuning for over 10 years on the multiple iterations of these trucks. What am I talking about is not "hard" on anything.

Take my current 17 as an example. In stock trim it's 3.73 and always wants to run too slow and downshift to some stupidly low gear on the slightest grade empty... but if you let out of it and let it upshift back to fifth gear and around 2200- 2300 at the speeds I am at it holds it with ease. Lock out 6th gear and that downshifting goes away... hmm. Easy solution is what I am in the midst of is 4.56 gears... no more problems. These engines need gear reduction and never need to be at sub 2000 rpm cruising. I never need the 1600 to 1800 rpm range ever and it's harder on fuel then it is at 2200 to 2300... not to mention that slightly higher rpm prevents this 4500 rpm downshift stupidity that the truck never needs to see in the situations I am in. Even a 4.10 geared truck with stock tires on these is geared too high.

Edited February 3, 2018 by SierraHD17

2016HD · February 3, 2018

5 hours ago, SierraHD17 said:

I don't really care nor do I want to listen to the thing at 4500 plus rpm when it comfortably does the pull at 2500 rpm. It's not harder on it and fuel economy in one of these HD heaps is irrelevant. Considering I said "empty" That has zero to do with heavily loaded. Even when loaded if I can make it stay in the higher gear (can't have it panned here or it's downshifting) and it pulls the grade easily there is no need to listen to it screaming away for nothing. I have been screwing with this junk both building and tuning for over 10 years on the multiple iterations of these trucks. What am I talking about is not "hard" on anything.

Take my current 17 as an example. In stock trim it's 3.73 and always wants to run too slow and downshift to some stupidly low gear on the slightest grade empty... but if you let out of it and let it upshift back to fifth gear and around 2200- 2300 at the speeds I am at it holds it with ease. Lock out 6th gear and that downshifting goes away... hmm. Easy solution is what I am in the midst of is 4.56 gears... no more problems. These engines need gear reduction and never need to be at sub 2000 rpm cruising. I never need the 1600 to 1800 rpm range ever and it's harder on fuel then it is at 2200 to 2300... not to mention that slightly higher rpm prevents this 4500 rpm downshift stupidity that the truck never needs to see in the situations I am in. Even a 4.10 geared truck with stock tires on these is geared too high.

I meant no disrespect to you and your knowledge. I have been in the industry for over 25years. So lets not argue experience. You say the trucks are geared to tall and that adding 456 gear will solve or help the issue. This is exactly the point i made. You are now regearing the truck in order to keep the rpm in a higher range. Its a small block Chevy. They are not built to cruise with the weight of these trucks at anything under 2000rpm at any sort of grade. This i AGREE with you. However on flat ground. No reason to not have it idle along at 1600-1800. Fuel economy is not your concern in an HD truck. But it is for a lot of people along with GM. IF you want to run at 2000-2500rpm all the time. Why not put 530 gear into it. And completely disable 5-6th gears. Example. 1980's 3/4 truck. 3speed auto. 4.10 gears small block chevy. cruising at 60mph around 2500-3000rpm. Hmm Good for mileage? NO. Good for towing? Yes. Good for the wear and tear of the engine and trans? No. These are not diesel Trucks! They do not have an efficient power range in the lower rpm!! anything basically under 2500. They are not meant to lug at under 2500rpm loaded or not loaded. For your application why dont you just tune out 5-6 gear? Install 4.56 and let it cruise at 2500-3000rpm all the time? Less load on the engine less fuel economy less shifting. My 2016HD shifts just fine loaded or unloaded. Going up slight grades unloaded it shifts out of 6th. Then steeper grades it will drop to 4th. It does not under light load drop 2 or more gears and scream into the 4500rpm range. While fully loaded towing 8000-10000lbs. On absolute flat ground it will cruise in 6th. anything other than flat ground it will use 5th and 4th into the 2500rpm range that you desire. IF pulling steep hills i keep it at 4500-5000rpm where it is designed to run and the torque is at its peak. SORRY to rant. But you say you dont want to hear the truck scream at higher rpms all the time? But you want to re gear so the truck stays in a Higher rpm Range? So no matter what it will always be at a Higher rpm???? I really dont see why you truck would drop 3 gears unloaded at slight grade and hit 4500rpm without you applying heavier throttle. Must be the 373? Cause with 411 that does not happen. ALSO did you order your truck with 373 gears? because they did not offer that option in 2016-2017 unless specifically asked for? ONCE AGAIN> NO DISRESPECT!! Just having a conversation

SierraHD17 · February 3, 2018

Why would I tune out 5th and 6th.... that's just idiotic and counterintuitive. Making the truck run at a reasonable crusing rpm in 6th gear is the point and then have mechanical advantage where I need it otherwise. Ford figured it out.... hell you can get 4.30's in a run of the mill Super Duty with the same size tires and same transmission ratios.

You need to understand that the truck holds 2200 to 2300 rpm fine with what I am doing..... Is 2200 rpm screaming in your head maybe? I don't know but I doubt it. But 4500+ sure is and I don't need to see it. Steep grades make it drop holding speed with the little bit of weight I carry... it's likely the 3.73 gears but it is what it is. I honestly lock out 6th on this truck and it doesn't do any stupid gear drops but then why have a 6 speed at that point.

The truck was an off the lot fleet order and I got it stupidly cheap with every other option on it I wanted including heated cloth buckets, console, Bose stereo and so on in a double cab. I have driven the 4.10 ones plenty and never felt it was worthwhile as an upgrade plus this just gives me that much more excuse to actually upgrade the gearing and add a Detroit Nospin at the same time. My exhaust drones from 1600-2000 rpm pretty bad and is quiet elsewhere.... this fixes that too lol.

You keep talking about towing... I don't tow... ever so lets forget about it. This truck will likely never hook to my trailer in its entire existence so I don't worry about what it does towing and I will deal with it if I ever do. My old LQ4 powered 05 pulls great and is just a better setup truck for that anyway.

My truck isn't stock and pulls surprisingly well at lower rpm just like every other 6 liter I have had. Peak torque stock is like 380 @ 4200 but they are producing 350 ft lbs at around 2500 rpm... mine makes more than that but how much is a guess so just say stock lol. The curve is pretty flat and with a tune and the limiter trash gone you can feel that. The trans tuning strategy is not the best but you mess with it and it's pretty good. Put some gears in it and well, you can have your cake and eat it too.

Edited February 3, 2018 by SierraHD17

2016HD · February 3, 2018

LOL. I agree with some of your statement. However creating a truck that is always cruising at 2300 rpm in 6th is also counter intuitive. At least while on flat ground. Now your first gear and almost second gear will be useless. Id have to check the ratio's but my guess would be 1st gear is now about as useful as 4low and now second becomes your usable first. If you are not towing or carrying a decent load? With an HD truck. Why not just get a 1500 6.2? Would have probably worked better.

I just got rid of my 04 2500 LQ4 and 4 speed auto, Sorry but the new truck gets better mpg and also has better towing capability.

I understand that you got a Great deal on the truck!! Thats always nice. However if your not using the truck for what it is designed to do? Why try and correct problems that others are having while actually towing? And fords 430 vs Gm with 4.11 really isnt that big a difference. Plus fords Trans gearing is worse.

Counter intuitive is. Re gearing a truck that does not tow. Or carry heavy loads. In order to get rid of an exhaust drone and install a Locker. Re tune the shift parameters to hold 5th longer. 6th is an overdrive. 1800rpm should be just fine on the flats? And Im sorry but I dont see why you are shifting into the 4500rpm range with a light load while going up slight inclines?? My lq4 never did this nor does my 2016 l96? It will tow my smaller 6500lb trailer in 4th at 3000rpm up decent grades out here in B.C? without issue? This Interested me that the 373 would make that large of a problem?? Let me know thanks.

And what tuning have you done to the trans? Thanks. EFI Live or HP tuners?

SierraHD17 · February 3, 2018

I had a 6.2 1/2 ton and it was utterly worthless for my purposes not to mention I am not interested in afm direct injected stuff.. I am ending this right here as I have my opinion and reasons and you can have yours. It's my truck, and I know what I need and want from it. I don't feel like writing novels about my personal opinion and I have a thread in the forum one down from here called 4.56 gears and a Detroit locker. I have written piles in there. No hard feelings hopefully lol. I use both EFI and HP tuners and currently own both. Have a good one.

Edited February 3, 2018 by SierraHD17

2016HD · February 3, 2018

No worries. PEACE! LOL. opinions all good. Hopefully our opinions helped the O.P some? LOL

SierraHD17 · February 3, 2018

Doubt it. Had nothing to do with the thread.

bobsiding · February 4, 2018

I bought a 17 hd truck with a 6.0. I had an 04 duramax with a stick, (sure miss that truck) we do a few camping trips in the mountains. have a truck camper and pull a boat or a trailer. theres a lot of difference between a gas and diesel and manual to auto transmissions. I wish that you could lock the trans in whatever gear you want. I hate going up a hill at 5000 rpm and especially when the trans is searching and cant make up its mind what gear it wants. I know all about tow and manual mode. in manual mode you get to pick the top gear. as soon as it pulls a little hard it jumps one or two gears. I hate that. drives me crazy. going from a stick to auto I hate that I have no control of whats happening.in gm sports cars you can get a auto trans that you can shift like a stick, why not a truck.if I could I would order another stick but that's not possible from gm. why cant you get what you want, like the old days when you ordered options not whole packages with junk you don't want or need. wheres progress.back in the 70 s and eightes a truck cost less than $20000 and you could order anything you wanted. engine, trans, gear ratio.interior color, (now all trucks have black interior). and what does a truck cost now. and how much junk is on there that you hate.doesnt gm care about there customer base and repeat buyers.its nice to go out and buy a new truck but after you have it awhile you notice all the bugs you have to live with until the next new one ,then it starts all over again. enough venting. gm, wake up. build trucks,not glorified cars. that we get to drive and make our own decisions. that don't drive themselves. I never minded shifting. I think the auto takes the fun out of driving. would you like if they took the sticks out of sports cars. wouldn't be fun driving anymore. awesome site

redwngr · February 4, 2018

Sounds like a duramax might have suited your towing requirements better.

Something about nearly 2.5 times the torque makes them pull hills much differently.

In another thread, someone compared 'inflation adjusted' prices. I was surprised how similar the 'good old days' pricing was to todays.

Jak860 · May 29, 2019

I know this is an old thread but I just experienced the same problem as the original post. I have a 2105 Silverado 2500HD 6.0, 6 speed automatic, 36000 miles. I was towing my loaded toy hauler that weighs in at roughly 10,000lbs. While climbing a long grade in manual 5th in tow haul mode the truck eventually slowed to under 40 mph in 3rd gear then shifted automatically into 2nd at 4200 rpm. Once the grade started to taper off I backed off on the throttle and expected an upshift into 3rd but it never came. Instead it stayed in 2nd even on the level with my foot completely off the gas. The only way I could get it to upshift is to move the selector up into neutral while coasting and then put it into drive range. It would then go into a higher gear. Several times when I tried to place it back into manual 5th it would drop all the way back into 2nd with high rpms. Then after driving awhile longer in drive range all went back to normal until it had to drop back into second while climbing a grade. It did this several times over 300 miles. I used to build and repair transmissions years ago. It acts like a stuck governor valve did way back when. I'm a little concerned about taking it to my local dealer as they don't seem to have the expertise or even the concern to a problem that is out of the ordinary. I have canvassed the web but haven't seen anything that may address my symptoms.