TSB For 2015+ 8 speed transmissions?

[noupf]

Hey guys, just got back from a 500 mile trip towing 2500 lbs in an enclosed V nosed trailer. I noticed that while driving at 70+ the tranny would never get into 8th gear. Mind you, i did have it in tow/haul mode, but i found it odd, then i remembered that I read somewhere ( on one of these forums ) that the 8spd trannys ( i think 2015+) had a recent TSB made available bc some guys were saying that at 75mph+ the tranny wouldn't go into 8th either ( i think these people were not towing anything in their complaints ), but i cant find anything on it.

I dont know if it was because i was physically exhausted ( whet motorcycle racing this weekend ), but on my drive home, the transmission seemed like it was fighting with itself ( if that makes sense ) to down shift when a lower gear was needed for some inclines. I felt like i had to get on the gas pedal a bit harder than normal to get the tranny to downshift. It just didnt seem smooth and fluid.

Again, i was beat and my legs and feet especially get tired after a day of riding the track, so it could be made up in my head, but it just seemed that the tranny needed a little extra uuummmph to get into the right gear when accelerating.....

I have a 2015 CC 4x4 3.92 Hemi sport.

Thanks

 

[drittal]

Towing an enclosed trailer at 70+ mph might have produced enough resistance to not allow the truck into 8th. Even if it's v nosed or not heavy. Weather, road and speed combined could have been enough.

I'm not sure if this is what is going on in your instance, but it is something to consider.

Sent from my SM-N900V using Tapatalk

 

[Ram48]

Yes there is a update for this problem. Don't know the name or number but go to your dealer and check the update's.

After this it is much better , also without a trailer

 

[TRXHemi]

I believe in the Tow/Haul mode, the transmission will NOT go into overdrive.

 

[RamCares]

Hey guys, just got back from a 500 mile trip towing 2500 lbs in an enclosed V nosed trailer. I noticed that while driving at 70+ the tranny would never get into 8th gear. Mind you, i did have it in tow/haul mode, but i found it odd, then i remembered that I read somewhere ( on one of these forums ) that the 8spd trannys ( i think 2015+) had a recent TSB made available bc some guys were saying that at 75mph+ the tranny wouldn't go into 8th either ( i think these people were not towing anything in their complaints ), but i cant find anything on it.

I dont know if it was because i was physically exhausted ( whet motorcycle racing this weekend ), but on my drive home, the transmission seemed like it was fighting with itself ( if that makes sense ) to down shift when a lower gear was needed for some inclines. I felt like i had to get on the gas pedal a bit harder than normal to get the tranny to downshift. It just didnt seem smooth and fluid.

Again, i was beat and my legs and feet especially get tired after a day of riding the track, so it could be made up in my head, but it just seemed that the tranny needed a little extra uuummmph to get into the right gear when accelerating.....

I have a 2015 CC 4x4 3.92 Hemi sport.

Thanks

Hi noupf,

The following TSB might help you out--it's the most recent one for the trans that I could find on your vehicle:

NUMBER: 21-064-15
GROUP: Transmission and
Transfer Case
DATE: November 21, 2015

SUBJECT:
Flash: 8HP70 Transmission Shift Enhancements
OVERVIEW:
This bulletin involves reprogramming the Transmission Control Module (TCM) with the
latest available software.
SYMPTOM/CONDITION:
The purpose of this software release is to enable the capability to capture non Diagnostic
Trouble Code (DTC) control module data through the Uconnect Data Recording system.
In addition, the following improvements are available.
2015 WK
· Improved upshift timing in eco, base, and hill modes and while using cruise.
· Improved 8-7, 3-2, and 2-1 downshift timing.
· Improved shift timing at higher altitudes.
· Improved torque converter engagement.
**2015 DS
· Improved 7th gear upshift timing.**





Kori
Ram Social Care Specialist

 

[crash68]

I believe in the Tow/Haul mode, the transmission will NOT go into overdrive.

Seventh and Eighth are technically both overdrive as sixth gear is 1:1.
Transmission are shifted in part by torque demand from the load. The Tow/Haul raises the rpms to get the engine further into the engine's torque band.
You probably have to get fairly close if not over the torque peak(4K rpms) for the trans to shift while towing(or loaded) and with 3.92 gearing 2100 rpms is about 72 mph on factory 17's(even faster with 20's) in eighth gear.
It's not that it can't go into eighth gear, just too much load for that amount of speed for it to upshift.
A taller rear end gear ratio will cause a truck to run in sixth instead of seventh to keep the engine in the same torque band.
Towing 3K (@70 mph) with an EcoDiesel, the truck will shift into and hold eighth gear(Tow/Haul on) due to the lower rpm of the torque peak(2K rpms).

 

[GP4L]

I towed my buddies boat over the weekend (his chevy broke down, lol) - I saw 8th a couple of times around 60mph with a very slight downhill while using cruise control in tow/haul mode. Not sure if the 2014 is any different, and I'm current on all software. Did pretty good. The boat was full of gas on the way to the lake, so I'd guess it's around 5000lbs behind my truck, plus 3 passengers, and a couple coolers. Mostly urban driving (stop lights, and 35-55mph speed limits), saw around 12mpg towing. Woulda been better if I wasn't idling at the ramp forever waiting for boating noobs to launch their boats... Lol

 

[6.7CumminsDrvr]

On the 8 speeds, Tow/Haul does not lock out the top gear as it did with the old 5/6 speed

 

[boomer135]

I'm in a 2016 w/ 3.92 and 8 speed. I'm towing a 7,000 lb trailer and I get in 8th with and without tow/haul mode.

Tow mode in my 2013 with 3.55 I never saw 6th

 

[QwikKota]

I'm in a 2016 w/ 3.92 and 8 speed. I'm towing a 7,000 lb trailer and I get in 8th with and without tow/haul mode.

Tow mode in my 2013 with 3.55 I never saw 6th

I don't think that's the best thing for the tranny. When I tow I select Tow/Haul and bump it down to 6th. If you are towing a light trailer with no aero worries overdrives are probably fine but 7k is a lot for OD.