The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2018 Ram 1500 Rough Shifting After Transmission Fluid Change - What's Wrong?

0

Chris P. · rep 0 · May 25, 2:32 AM · 1 replies · solved · Question

Vehicle: 2018 Ram 1500 Big Horn

Hey everyone, I recently decided to tackle a transmission fluid and filter change on my 2018 Ram 1500 Big Horn with the 5.7L HEMI. I followed a few online guides and thought I did everything right, but now my truck is shifting really rough, especially from 1st to 2nd and sometimes into 3rd.

I used what I believed was the correct Mopar ATF+4 fluid and a new filter kit. I measured what came out and put the same amount back in, then checked the level with the engine running and warm. It seemed okay, but the shifts are definitely not smooth like they used to be.

Could I have used the wrong fluid, or maybe there's air in the system? Is there a reset procedure I missed? Any advice for a DIYer would be greatly appreciated before I take it to a shop.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:32 AM

0

ClearTheCode admin answer:

It sounds like you're experiencing common issues after a DIY transmission fluid service. Several factors could contribute to rough shifting, especially if the procedure wasn't followed precisely or if specific details for your Ram's 8-speed transmission were overlooked.

  1. Verify Fluid Level and Type: Even if you measured, the fluid level in Ram's 8-speed transmissions is critical and must be checked with the transmission at a specific temperature range (typically 180-200°F or 82-93°C) using a special dipstick or diagnostic tool to monitor temperature. Using Mopar ATF+4 is generally correct for older 6-speed transmissions, but the 8HP70 (8-speed) found in your 2018 Ram 1500 requires Mopar ZF 8&9 Speed ATF (part number 68157995AB or equivalent). Using ATF+4 in an 8HP70 will cause shifting issues and potential damage. This is a critical distinction.

  2. Adaptive Learn Reset: Modern transmissions, especially the ZF 8HP70, have adaptive learning strategies. After a fluid change, the transmission's computer might need to re-learn shift points and pressures. Sometimes, a simple battery disconnect for 15-30 minutes can initiate a partial reset, or a full reset can be performed with a capable scan tool (e.g., wiTECH or equivalent).

  3. Filter Installation: Ensure the new filter is properly seated and sealed. An improperly installed filter can lead to cavitation or insufficient fluid pressure, affecting shifting.

  4. Air in System: While less common to cause severe rough shifting, air can be introduced. Driving gently for a bit allows the system to cycle and purge air.

When to See a Shop: If you've confirmed the correct fluid type and level, and the issues persist, it's highly recommended to visit a qualified Ram dealership or transmission specialist. They have the proper diagnostic tools to:

  • Accurately check the transmission fluid temperature and level.
  • Read any stored trouble codes (even if no CEL is on).
  • Perform a complete adaptive learn reset for the transmission control module (TCM).
  • Diagnose internal transmission issues if the problem isn't fluid-related. Continued rough shifting can cause accelerated wear.
Menu

Help & account