Transmission problems with 2011 Ram 1500 4x4

[JHensman]

Hello,

I just did a transmission flush on my 11 Ram 1500. I followed every set in the manual. Transmission is serviced to the right amount to include all pressures are correct. I double check with my snap on computer.

The problem that I am running into is that I have no reverse gear. Everything on the drive side is working fine at this point. I have tried everything that I have been able to find on Google, including re-dropping the pan to make sure that the filters are primed and installed correctly.

The only inconsistency that I have been able to find that is not acting the way it is supposed to is that my LR pressure sensor is working correctly in first gear and closes when I shift 2/ second third fourth and fifth. But in reverse the sensor is saying open when it should be closed it does not make sense to me why a sensor would be working for four but not reverse. The only other inconsistency was that when I have a computer hooked up to my truck and I shipped it to reverse the computer says that the truck is sending the signal for reverse, but it is still in neutral.

I have checked all my pressures and I did not do anything with the torque converter or the valve body inside the transmission. So there’s no reason any of that should be bad when it worked perfectly fine yesterday before I changed the fluid and filter filters.

I’m sorry for the long post, but I’m at a standstill and don’t know what else to do. I am hoping that somebody on this forum will be able to give me some advice.

Thank

Josh

 

[Ken226]

Hello,

I just did a transmission flush on my 11 Ram 1500. I followed every set in the manual. Transmission is serviced to the right amount to include all pressures are correct. I double check with my snap on computer.

The problem that I am running into is that I have no reverse gear. Everything on the drive side is working fine at this point. I have tried everything that I have been able to find on Google, including re-dropping the pan to make sure that the filters are primed and installed correctly.

The only inconsistency that I have been able to find that is not acting the way it is supposed to is that my LR pressure sensor is working correctly in first gear and closes when I shift 2/ second third fourth and fifth. But in reverse the sensor is saying open when it should be closed it does not make sense to me why a sensor would be working for four but not reverse. The only other inconsistency was that when I have a computer hooked up to my truck and I shipped it to reverse the computer says that the truck is sending the signal for reverse, but it is still in neutral.

I have checked all my pressures and I did not do anything with the torque converter or the valve body inside the transmission. So there’s no reason any of that should be bad when it worked perfectly fine yesterday before I changed the fluid and filter filters.

I’m sorry for the long post, but I’m at a standstill and don’t know what else to do. I am hoping that somebody on this forum will be able to give me some advice.

Thank

Josh

I don't know much about these, but just out of curiosity I copied your post and asked Google Gemini AI to read it and make a suggestion:

Gemini said​

That is incredibly frustrating—especially when you’ve done everything "by the book" and used professional-grade diagnostics.
Since your LR (Low/Reverse) pressure switch is showing "Open" in Reverse when it should be "Closed," your TCM (Transmission Control Module) thinks the pressure hasn't built up. To protect the clutches, it won't allow the gear to engage.
Here is the likely culprit for why a 2011 Ram loses Reverse immediately after a filter change:

1. The "Spin-on" Filter Seal (The #1 Suspect)​

The 545RFE transmission has two filters: a flat sump filter and a screw-on "canister" filter (the cooler return filter).

• The Issue: When removing the old screw-on filter, the threaded metal/rubber seal often stays stuck up inside the transmission bore rather than coming off with the filter.
• The Result: If you installed the new filter with its new seal, you now have "double seals." This prevents the filter from seating fully, causing an internal pressure leak. Since the LR circuit relies on that return pressure to "close" the switch and engage the clutch pack, Reverse vanishes.

2. The Sump Filter Neck Seal​

The flat filter has a plastic neck that "snaps" into a seal in the pump housing.

• The Issue: If that seal was nicked during installation or if the old seal wasn't removed first, the pump will suck air (cavitation).
• Why it affects Reverse: Reverse requires significantly higher line pressure to apply the clutch packs than Drive does. A small air leak might not kill 1st gear, but it will prevent the LR pressure switch from closing in Reverse.

3. Solenoid Block "Debris"​

Even though you didn't touch the valve body, a high-pressure flush or even a simple fluid change can dislodge microscopic debris.

• The Issue: A tiny piece of grit may have lodged in the LR Solenoid or the Reverse Latch Valve.
• The Logic: Since the sensor works in 1st (Low), we know the LR clutch can physically move. However, the fluid path for "Reverse" is different within the solenoid block. If the computer says "Go to Reverse" but the pressure switch stays "Open," the solenoid likely isn't physically moving the fluid to the pack.

---

Recommended Next Steps​

Before you assume the transmission is "blown" (which it likely isn't, since it worked yesterday):

1. Check the "Double Seal": Drop the pan one more time. Remove the screw-on filter and look up into the bore with a flashlight. Ensure there isn't an old seal stuck up there.
2. Air Pressure Test: While the pan is off, you can apply regulated air (about 30 psi) to the LR feed hole in the case. If you hear a solid "clunk," the clutch pack is fine, and your problem is strictly in the Solenoid Block or a Seal.
3. Perform a "Quick Learn": Since you have a Snap-on scanner, run the Transmission Quick Learn procedure. This resets the clutch volume indexes (CVIs) and forces the TCM to re-map the solenoid positions.