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I'm getting the P0731 code for incorrect 1 gear ratio! Before it was P0730?

Tiny
WILLIE HURLOCKER
  • MEMBER
  • 2005 DODGE MAGNUM
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 135,000 MILES
This freaking wagon man! Ken, now I'm getting the P0731 code for incorrect 1 gear ratio! Before it was P0730. I changed the fluid and filter. I put back in what I got out! It was driving fine. My mother needed to go to the grocery store, then right down the road it went into limp mode! So, I came back and checked the fluid with a temperature gun and the 100 ' dip stick with it in drive. Added a little bit more fluid. It drove fine for a mile and went back into limp mode! Do you think my diablo tuner could be causing this problem? This freaking car man is nothing but freaking trouble and just got my badge for Magnum Mafia and have a meet in a month! Well, I got a p0715 turbine sensor. Do these codes all have to do with low fluid, in common?
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Wednesday, July 12th, 2023 AT 12:20 PM

12 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,909 POSTS
Yes, the turbine sensor can cause this, but I need to ask what kind of fluid did you use because this car takes only one kind of fluid and if you put the wrong fluid into the transmission, it will act this way. Here is the location of the sensor so you can change it out and clear the codes.

Mopar ATF +4, Automatic Transmission Fluid is the recommended fluid for DaimlerChrysler automatic transmissions.

Both input speed sensors are part of the lead frame portion of the valve body inside the transmission. Check out the images (below). Please let us know how it goes.
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Thursday, July 13th, 2023 AT 11:59 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,205 POSTS
Hi,

When you checked the fluid, it should have been in park or neutral. If you checked it in drive, the reading would be incorrect. At operating temperature, on a level surface, and with the vehicle in park or neutral (check the dipstick for requirements P or N), check the fluid level. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-and-add-transmission-fluid

Note, one of the possible causes of this code is low transmission fluid.

Let me know.

Joe
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Thursday, July 13th, 2023 AT 12:01 PM
Tiny
WILLIE HURLOCKER
  • MEMBER
  • 83 POSTS
I use nothing but Mopar! I just changed the filter and fluid!
I used a temperature gun to check temperature 170* and on the stick it was at 60mm.
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Thursday, July 13th, 2023 AT 12:03 PM
Tiny
WILLIE HURLOCKER
  • MEMBER
  • 83 POSTS
Yes, all of them codes have that in common. That's why I keep checking it. It drives fine for a while then starts acting up and going into limp mode. I clear codes, check fluid and it goes fine for a day or 2. I have a i3 diablo tuner, think that could be the problem? I don't mess with the gear ratio though!
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Thursday, July 13th, 2023 AT 12:06 PM
Tiny
WILLIE HURLOCKER
  • MEMBER
  • 83 POSTS
It says in the book to check fluid with it in d or r?
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Thursday, July 13th, 2023 AT 12:07 PM
Tiny
WILLIE HURLOCKER
  • MEMBER
  • 83 POSTS
How about the tail sensor at the end of the transmission? The other day it was really loose I tightened it back and used a punch to keep it from coming loose again.
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Thursday, July 13th, 2023 AT 12:08 PM
Tiny
WILLIE HURLOCKER
  • MEMBER
  • 83 POSTS
Is there supposed to be this much play in the rear end? I turned the center carrier bearing around as you suggested and it's a lot worse! Now I'm getting code p2767 turbine sensor which also has in common with the low fluid/dirty fluid! If the carrier bearing is a lot better with no vibration installed backwards, there has to be something way out of whack, correct?
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Thursday, July 13th, 2023 AT 9:18 PM
Tiny
WILLIE HURLOCKER
  • MEMBER
  • 83 POSTS
Iis there suppose to be this much play in the rear end? I turned the center carrier bearing around as you suggested & its alot worse! Now im getting code p2767 turbine sensor which also has in common with the low fluid/dirty fluid! If the carrier bearing is alot better with no vibration installed backwards, there has to be something way outta whack, correct?
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Thursday, July 13th, 2023 AT 9:18 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,909 POSTS
It is hard to see in the video what's going on, can you please add more light? Here is more information on the problem.

The P0731 code on your 2005 Dodge Magnum indicates an incorrect gear ratio for first gear. This means that the ratio between the input speed and the output speed of the transmission's first gear does not match the expected value.

The P0730 code you mentioned earlier also indicates an incorrect gear ratio, but it is a general code for the transmission and doesn't specify a particular gear. The P0731 code specifically points to first gear.

There can be several potential causes for this issue, including:

Low transmission fluid level or poor-quality fluid: Ensure that the transmission fluid level is correct and that the fluid is in good condition. If it is low or degraded, it can cause gear ratio problems.

Faulty transmission shift solenoid: The shift solenoids control the engagement of different gears in the transmission. A malfunctioning shift solenoid can cause incorrect gear ratios.

Internal transmission problems: Issues with the transmission gears, clutch packs, or other internal components can lead to incorrect gear ratios.

Faulty transmission control module (TCM): The TCM is responsible for controlling the operation of the transmission. A faulty TCM can send incorrect signals to the transmission, causing gear ratio issues.

To diagnose and resolve the problem, you may consider the following steps:

Check the transmission fluid level and condition: Ensure that the fluid level is correct and that the fluid is not contaminated or degraded. If necessary, perform a transmission fluid change.

Inspect the transmission wiring and connectors: Check for any damaged or disconnected wiring or connectors related to the transmission system. Repair or replace as needed.

Test the shift solenoids: The shift solenoids can be tested using a diagnostic tool or multimeter. If a solenoid is found to be faulty, it should be replaced.

Scan the TCM for trouble codes: Use a diagnostic scanner to retrieve any additional trouble codes stored in the TCM. These codes can provide more specific information about the problem.
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Friday, July 14th, 2023 AT 9:25 AM
Tiny
WILLIE HURLOCKER
  • MEMBER
  • 83 POSTS
I use Mopar atf+4 fluid and filter. It's at 170* and 62ish mm on the stick. Fluid is new so it is perfect so far! I'm kind of leaning towards this darn i3 diablo tuner I've got. When I put a tune on all but the check engine lights are on, but it drives fine. Holley doesn't know why all the lights are on! Its updated I check it every day!
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Friday, July 14th, 2023 AT 9:35 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,909 POSTS
It does sound like a programming error. Does the codes go away without the tune as well?
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Saturday, July 15th, 2023 AT 10:11 AM

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