Engine/ transmission issue

So I just bought this truck, and it's acting odd to me. It's a 2015 ram 1500 tradesman, with the 5.7 hemi, with I believe the 6 speed and some performance upgrades. It's got less than 50k miles on it which was a huge selling point. Truck runs great when it's warm out or when you have your foot in it, but when it's under 40°f outside and your rolling through town doing 30, the engine lights quite a bit like it's a manual that you need to downshift. Dealer took it for a test drive and said it shifts fine but I know they had their foot in it cause the mpgs dropped bad. They also topped off the trans fluid and did a "quick learn". Any idea how to record and prove the problem so I don't get hosed when my warranty expires and whatever is causing this gets to come out of my pocket? Thanks guys for your help!

Try using tow haul and let me know if it EVER does it in TH mode. Stick around, more information coming, but just do that thing next time it is cold, put rfe in TH mode and see if there are any undesirable things. I will later post the weaknesses of the rfe which you have, they come from the valve body and with your miles it is a very good move to upgrade VB, and I will send you the info, but first things first. Welcome to the board.

Thanks for the welcome. It's supposed to be in the 30s when I get off work so I'll try it and post back. Also if it is the valve body, how would I prove it so I can get it fixed under warranty? They gave me 3 months/3000 miles power train

The bad thing about the 5/6 speed transmission in my truck is that it always upshifts too soon. Tow/Haul helps. But the cure is the Slap Stick that my truck has.

I'll never be a fan of any automatic transmission. But if I can hold the gears until I want it to shift, I'm ok with an automatic.

Take it to a transmission shop and there likely would be a charge. The problem is valve bodies leak, the other problem is when transmission fluid is cold it is thick, so I'm not sure you can get this proof easily especially if no codes, it could be either thing. Can you explain the situation in more detail, does this do it when transmission is warm? Can you add everything you can think of, why do you need to down shift? the shift is hanging? I havent heard anything that would call this a transmission failure eminent type thing, convince me with as much detail as you can think of.

Before you start with the big stuff, start small bc that's often where the problems lie (and what a lot of mechanics skip). You wouldn't believe how many mechanics skip basic troubleshooting, looks for the 'big kahuna' which can cause owners a lot of expense and downtime till someone finds the small issue, or replaces a bunch of things and stumbles on the issue a good troubleshooter would have caught right away:

CORE BASICS:
A lot of people don't want to focus on the basics, but they're important and can be a the problem, or contributing problem. Clean your battery terminals and make sure the grounds to the engine/body are good (that costs nothing if you do it yourself). Seriously, the electrical signals go through the grounds so if they are so-so, that's going to affect signals to the computer, tranny, etc. Wiggle the fuses and relays to ensure there isn't any micro-corrosion affecting any circuits (takes 1 min, cost's nothing). Is the tranny fluid at the appropriate level? What is the condition of it? I might slide under the tk and wiggle the connectors at the tranny (again a 2-min job that costs nothing). Is the air filter dirty and plugged ..or new & clean? (can affect airflow if really dirty). Wiggle the MAF sensor connector. Are there any Check Engine lights on? If so, which? Can you hear any obvious vacuum leaks? All of these things above should take no more than 15 minutes to check, combined.

TEMPERATURE SENSOR:
Then I would probably start with making sure the computer is getting a good temperature signal (since this seems to be temp related). What is the temp the truck running at ....and is it accurate? Transmission shifting is controlled by the computer which gets it's information from sensors. And temperature sensors are a big part of that (so it pedal position, speed, airflow too). I would start with the temperature sensors (ambient and engine temp).

If you have a scanner, you could hook up and observe the temp when the truck is cold and compare to the actual outside air temperature. If you don't have a scanner, then you can take a multi-meter and ohm out the temp sensor pins at the sensor ..and compare to a temp/ohms scale. Sensors can drift. I had a bad one a couple different vehicles in the past and yeah, it screws up cold weather operation bc the truck 'thinks' it's different temp and delivering the wrong fuel, etc.

And do the same when the truck is warm ...but double-check the actual coolant temp by shooting the temp at the engine metal coolant outlet (where the upper radiator hose connects) ..with an infra-red temp gun. You want to make sure the actual temp is the same as what the sensor is reading when warm (the sensor the TIPM is seeing).

Beware some vehicles have two temperature sensors: one for the gauge, one for the computer. When that happens, the gauge can read normal, but the TIPM might be getting an erroneous signal. I honestly don't remember if the 5.7 in 2015 has one or two. I'm sure someone here will chime in.

MAF SENSOR:
From there you might ohm out the MAF signal. A faulty MAF, or even one which is at the low end of it's 'normal' range (but not enough to send a CEL) can cause problems too. What's it's voltage output? There are youtube videos how to check this. They can be cleaned with special MAF cleaner (results vary).

THROTTLE BLADE:
Oh, and you should also pull off the air intake to the throttle blade. Open the throttle blade and look for carbon deposits. I know it sounds unrelated, but, trust me, small things can make a big difference, and a lot of owners overlook this basic cleaning area. If there's visible dark varnish on the bore or plate, clean it with throttle-body cleaner (not carb cleaner) and a nylon brush (not steel or brass).

A shop makes money off a tranny replacement, not so much off the small things. That's where a lot of them will steer you. Don't overlook the basics.

You might also check your PVC valve too and EGR plumbing. I know this sounds small annd inconsequential, but I had a Jeep Grand Cherokee with a V8 I bought and the shifting was all over the place too. The former owner spend a lot of money and couldn't get things ironed out. They said it needed a new tranny. So I got a good deal. It had a bunch of small easy-to-overlook things that had to be sorted out. One of them was the plastic piping chrysler uses for the EGR. Now, I don't know what they use on the 2015 Rams, but on my Jeep, the rubber hose ends for the piping were hard brittle and badly cracked. They were leaking like crazy. PVC was plugged. These caused all sorts of driveability issues. Once ironed out it made a big difference. But still sometimes shifted quick into gear.

Ultimately there was also a flaky solenoid in the transmisson which needed to be replaced. I let the dealership do it bc it was well below zero outside at the time (other projects in the garage). It costs $300 but between the EGR, PVC, cleaning the other sensors and the new trany solenoid it ran like a new vehicle after that and has since for another 100k (daughters car now). A combination of small easy-to-overlook items and a larger solenoid.

If that's an aftermarket warranty and not a factory warranty good luck with getting any work done to cure a driveability issue. Aftermarket warranty only covers a total failure and even then they can claim abuse by the owner.
As it is you may be having issues with the valve body or a low pressure problem.

Ultimately, assuming none of the other basics I listed (above) are at issue, there's a strong chance it's a bad Transmission solenoid. Your issue sounds exactly what our Jeep was doing and it's the same basic root tranny. It's fairly common on those trannys, do some google searches. You can replace yourself if you have mech skills. Or take it to a Chrysler dealer and have them troubleshoot in case it isn't that. But all the basic things should be investigated before a person condems the solenoid. I went that route. Or a good tranny shop. Anyone who says you need a new tranny or expensive work, take it somewhere else!!! Explain to the shop you want basic troubleshooting done, and call you before any work/parts are installed. After it's replaced the computer needs to 'learn' the new shift pattern, so it might take a couple days to show resolve.

They sell kits on certain sites. If it is the issue, brand new fluid/filters would be a good idea since you haven't owned it much ...and 50K would be a great age to install new fluid (before it gets too many miles on it). You get all the floating debris suspended in the oil, out of the tranny. Great for tranny longevity. But the issue could be a $15 temp sensor too, so don't overlook that.


The link above is for illustration purposes. Double-check transmission & fitment.

@Burla tried it tonight in tow/haul mode and tried to do a side by side comparison, but it oddly wasn't doing it tonight and the girlfriend had plans so I couldn't just drive around trying to duplicate the issue. It did run the rpms a bit higher in tow/haul than in normal.

@Jeepwalker that's a good list of things to check. Battery terminals are good n clean, no symptoms of power issues like poor voltage or flickering lights but I'll check for corrosion. Air filter looks brand new, and no check engine light. Dealer said they topped off the trans fluid but it was in the ok zone before they topped it off, maybe a 1/4 qt below full but well above the low mark. Visually it looked and smelled ok, nice bright red. You may be on to something with the temperature sensor, oil and coolant always start at 100°f even if the truck hasn't ran overnight and the ambient temperature is below 50. Can't remember what the transmission temp starts at but still a bit higher than ambient. Once the vehicle is up to temperature the gauges seem accurate, going by the needle gauge and the vehicle info on the lcd screen. And it's not vehicle temp but ambient temp that seems to have an effect. I have an elm type Bluetooth code reader, so I'll try pulling any temperature sensor info I can and post back an update.