P0729: Gear 6 Incorrect Ratio DTC Trouble Code

[Kenneth B Sims]

2015 Ram 1500 Express 5.7l 3.21 Diff
84k miles
While recently towing my 5k lb travel trailer on the interstate in Tow/Haul mode, I've noticed a bump when it would downshift on a medium grade from 7th to 6th gear. This past wknd, it bumped pretty hard downshifting into 6th and went into safe mode and threw a

P0729: Gear 6 Incorrect Ratio DTC Trouble Code​

I had the Chrysler dealership run a scan on it and this is the code they found.

We were stranded 130 miles from home and Good Sam would only take me 50 miles and then $500 more to get me home. No deal! I tested the vehicle and it seemed to be functioning in normal mode. I put the truck in Tow/Haul mode and in 5th gear and drove the TT home keeping it around 2500 rpm. It did fine w no bumping or issues and tranny temperature was good, never over 195°.

I've read the possible reasons for this problem can be:

• INPUT SHAFT SPEED SENSOR FAILURE
• OUTPUT SHAFT SPEED SENSOR FAILURE
• LINEAR SOLENOID 2 CIRCUIT HIGH / RESISTANCE / MECHANICAL ERROR
• LINEAR SOLENOID 4 CIRCUIT LOW / RESISTANCE / MECHANICAL ERROR
• LINEAR SOLENOID 7 CIRCUIT HIGH / RESISTANCE / MECHANICAL ERROR
• SHIFT SOLENOID 1 CONTROL CIRCUIT LOW / CIRCUIT OPEN / FAILURES
• VALVE BODY INTERNAL FAILURE
• INTERNAL TRANSMISSION PROBLEM
• TRANSMISSION CONTROL MODULE (TCM)
• also..
  • Not enough transmission fluid
  • Dirty transmission fluid / filter
  • Damaged wiring/connector
  • Malfunctioning transmission pump
  • Failing torque convertor clutch
  • Bad solenoid
  • Problems with fluid pressure
  • Valve body issue
  • TCM failure
  • 
    
  • I called Aamco and the guy says it's most likely internal instead of an external sensor issue. They want me to bring it in next Wednesday.
• Question: Any ideas on what you guys would try before I'm at the mercy of an expensive tranny shop?
• I'm willing to change sensors, change tranny fluid n filters and even replace the solenoid pack or do you think it's something more invasive? Thanks for any help!

 

[gozarca2]

so i had a VERY similar issue just this past weekend on my 2014 w/65k miles. I was trying to climb up the tejon pass from LA back going north. The transmission was running very hot, around 250-255 and i think that was my main issue. I limped to an offramp, likely with the tranny stuck in 5th or 6th gear. I limped to a gas station, sulked (didn't stop car yet), then limped across the street while still towning my trailer. It may have been stuck in like 3rd gear as it rev'd very high and didn't move much to pull the trailer across the street. I shut off the car and walked to 3 mechanics. about 30-40min later i came back to the truck to drive it & trailer across the street to drop it off and it seemed to then run just fine w/no issues. The mechanic checked the fluid and he said it looked fine. I'm hoping it just tripped the limp mode from overheating. I'm pondering not only a full flush of tranny but a new heater/cooler unit or even a heating bypass kit, since it seems to always run in the 180-200 deg range (8HP70 i guess run that hot by design?)...so what ended up happening to you?

 

[burner71]

I have a 2015 Durango and was driving across Louisiana on a 107 degree day with cruise set at 97mph. After about 2 hours the cruise disconnected and threw that code. I limped into a gas station and let it cool a bit. Took the rest of the way home at 75mph or less and it never happened again.

My 2500 on the other hand I had to replace the shift solenoid.

 

[Edward Tamasi]

I have the same problem with my 2012 1500. I was told I need a rebuild. It has been rebuilt twice. I searched more options and it looks like upgrading to the 8hp70 is the most recommended. I do not feel like spending 10K for a swap. I would like to keep the 65RFE any suggestions for clutches, solenoids, valve bodies, etc...

 

[smoothee]

I have the same problem with my 2012 1500. I was told I need a rebuild. It has been rebuilt twice. I searched more options and it looks like upgrading to the 8hp70 is the most recommended. I do not feel like spending 10K for a swap. I would like to keep the 65RFE any suggestions for clutches, solenoids, valve bodies, etc...

You can do the 8 speed swap for far less than 10k. IMO it's a waste of time and money messing with the rebuilds, the factory RFE's seem to hold up better than the rebuilds usually do, even the "bulletproof" units

 

[Redfin ss 272]

I have 2014 Ram 1500 bad shift btw 5 & 6 code p0729
Dodge replaced trans & Torque convertor I have life time extended warranty got when brought PU because of all electric shifter

 

[Stoyan]

I have 2015 Ram 6.4 66RFE and my truck was on limp mode ,goes to 4th gear and stuck there.I had to restart the engine end go up to 4th gear and stuck again.So,i put heavy duty valve body and also rebuilt shift solenoid and this kinda fix the problem but new one came.Now it was jumping on every gear so i had to re-learn the transmission with a computer so will be good again ,but not 100%.After the adaption trans start shift very smooth up but when i want to shift down it was jumping from 6 to any lower gear. And sometimes stuck on 5th gear.
I am in hell again.Next week i will call the dealer to see if they can do anything.
Any suggestions !!!