Transmission's third gear not working?

CHRISTIAN CHENARD

MEMBER
2007 DODGE RAM
4.7L
V8
2WD
AUTOMATIC
432,000 MILES

My Canadian truck listed above 1500 with 545rfe transmission, 2wd won't go in third gear (go neutral). All this happened all of a sudden "one day the truck was driving fine, was parked for 2 days and on the 4th day it won't go in 3rd gear.
Starts fine, goes 1st to second fine and then when it's time to go third it just goes like in neutral.
Fluid looks good and don't smell burned, don't see anything wrong with valve body and no muddy stuff in the pan.
Tried unplugging main connector and drive it to see if it starts on 1st or 3rd, and it goes on 1st.
Did not find any electrical issues.
Can it be the OD clutches that are worn out?
Thanks for info.
Christ

5 Replies

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

Chances are it is a shift solenoid. However, there are several possibilities, and I need to know where to start.

Have you checked to see if there are diagnostic trouble codes? If you haven't, that is the starting point. What really needs to be done is a can-scan.

CAN stands for controller area network. Basically, the different modules are all tied together via a few wires. This type of scan will retrieve codes regardless of the module storing them.

Here is a link explaining how it's done:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know if you can have this done or if you already have done it. If you have, let me know what codes were retrieved.

I will watch for your reply.

Take care,

Joe.

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Friday, February 17th, 2023 AT 9:14 PM

CHRISTIAN CHENARD

MEMBER
6 POSTS

Ho yes forgot the code.
My code reader said, p0733.
Which is incorrect gear ratio, third gear. Nothing else.

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Saturday, February 18th, 2023 AT 7:07 AM

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

Okay, that helps. I have the diagnostics related, but I need to explain something.
The transmission system uses two speed sensors, one to measure input RPM and one to measure output rpm. These inputs are essential for proper transmission operation. Therefore, the integrity of this data is verified through the checks at the start of the diagnostics.

I attached everything related to the P0733. Take a look through them and let me know if you are comfortable performing the tests. If you need additional information, let me know.

Take care,

Joe

See pics below.

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Saturday, February 18th, 2023 AT 5:55 PM

CHRISTIAN CHENARD

MEMBER
6 POSTS

I Looked through pics and I don't have the scan (code reader) powerful enough, the numbers, and the knowledge to perform any of these test and teardown. Maybe I can check input and output speed sensor, but I don't have the numbers I need to compare with and need pics that show which wire is what and procedures.

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Saturday, February 18th, 2023 AT 6:37 PM

CHRISTIAN CHENARD

MEMBER
6 POSTS

I checked the input and output seep sensors, input tested 0.47 oms, power at 4.25v and ground continuity at 0.22oms. Output tested at 0.46-47oms, power at 2.4v and ground continuity at 0.00 oms. Could not do the magnet test because I couldn't take the sensors off w/o breaking the bolts.