Code P0748, broken piece of ring in transmission pan

ACOMMONVISION

MEMBER
2001 DODGE RAM
5.9L
V8
2WD
AUTOMATIC
173,000 MILES

Hi, I own the truck described in the subject.

About 3 weeks ago I was stuck in some mud, and I revved the engine, in Drive at 0 mph to get out of the mud and the truck reached about 3,000 RPM and then the check engine light came on. Code p0748.

Fast forward, I dropped the transmission pan, and the transmission fluid was very dirty. I knew that and hadn't been changed for about 5 years or about 35,000 miles.

In the bottom of the pan was a broken piece of a ring, which I've narrowed down hopefully to being overdrive clutch assembly? Ring or snap ring?

The truck has code p0748, which I've looked up and says Governor pressure solenoid. I bought a new governor pressure solenoid but did not install it when I had the pan off because I saw the broken piece of the ring and figured maybe there was a short in the valve somewhere.

I know I could have put the solenoid in to see if that would have fixed it, but with the broken ring I figured the solenoid was probably okay.

Upon a little bit of research, if it is the OD clutch assembly ring? Not sure if that's the proper terminology, I think you can repair it by taking the overdrive assembly off of the back of the transmission.

In which case and if it is this particular ring and the rest of the transmission is indeed fine, I would like to go this route. I'm looking for some help to clarify what options I have moving forwards.

When I took the transmission pan off the fluid was dirty, but it didn't smell burnt, and there were no metal shavings whatsoever, on the magnet, or in the pan, only the broken piece of ring.

I put a new filter and transmission fluid in, so the truck currently has fluid and is drivable in limp mode. If you put it in Drive it starts in third gear, then seams to shift 2nd then back to 3rd as you accelerate, but stays in third.

If you start it in 1st gear manually and shift up to second, then drive its smooth and fine. Drive still stays in third though. Stuck or shorted valve cause of broken ring?

So, I hope the rest of the transmission is sound.

I'm hoping to be able to just fix this one part and get myself back on the road. I'm a gardener and use my truck to make a living. Thank you for any help.

7 Replies

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

The OD unit can be removed from the rear of the transmission. However, how big was the broken ring you found? Does it look like a snap-type ring that would be used to secure clutch packs?

If possible, take a pic of the ring you found and upload it for me to see. If you look at the pic below, it's an exploded view of the OD clutch assembly. I highlighted different retainers, snap rings, and so on. Does what you found look like it could have come from one of these retainers?

Let me know.

Joe

See pic below.

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Friday, January 14th, 2022 AT 10:09 PM

ACOMMONVISION

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4 POSTS

Hey Joe.

Thank you very much for your help. Here's an image of the broken ring found in the pan.

Any guidance you can provide for me I would be extremely grateful for!

I'm Raring to get this truck back on the road you know bro!

-garret

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Saturday, January 15th, 2022 AT 1:00 PM

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Looking at the pic, I believe you are correct. That appears to be a piece of a retainer and based on the code, chances are it is in the OD clutch assembly.

Before just replacing the sensor, the clutch pack assembly should be removed and inspected. However, because all clutch packs have different retainers, the sensor could be the issue and the broken retainer you found may have come from a different location.

The only way to check is to remove the assembly. I attached three pics below showing how to remove the rear section exposing the components. Try this and check to see if there is any evidence of a problem.

If nothing is noticed, we have two choices. Remove the transmission and disassemble it to find the broken retainer or put the new sensor in and hope that it takes care of it. The broken retainer may still be holding things in place. However, that is going to be for a limited time

Let me know what you decide or if you have other questions. Additionally, if you want the entire disassembly procedure for the OD assembly, let me know. It is quite extensive.

Let me know.

Joe

See pics below.

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Saturday, January 15th, 2022 AT 3:19 PM

ACOMMONVISION

MEMBER
4 POSTS

I knew I should have at least put a new sensor in there (Governor solenoid) to see if that would have fixed it for the time being. I had a new solenoid on hand and the pan was off.

I put new transmission fluid in to drive it home, so I would have to drain the pan and buy new fluid again, right?

Do you think it's worth the $200.00 to go get the new solenoid and transmission fluid, drop the pan put the new solenoid in and see if it's fixed? Or what would you recommend first?

Removing the overdrive assembly?

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Saturday, January 15th, 2022 AT 3:27 PM

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

You could save the fluid that comes out and reuse it. Just make sure the pan is clean. As far as the assembly, when you start taking the clutch and hub assembly apart, it becomes involved.

My biggest concern is that the part is from a different clutch pack and the solenoid itself may have at least temporarily taken care of the issue. The issue is it really needs to be identified and replaced before more happens. If nothing is found in the OD assembly, then the transmission needs to be removed, disassembled, and inspected. Which will be much more involved.

Let me know what I can do to help.

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Saturday, January 15th, 2022 AT 4:39 PM

ACOMMONVISION

MEMBER
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This has been very helpful, thank you.

I agree identifying the origin of the part is important and of concern.

I would need help myself to raise the vehicle and take the rear end of the assembly off to diagnose the overdrive unit. Though I would like to go that route.

If that is done, and the part is indeed from the overdrive assembly the next step, just to clarify, would be removing just the overdrive assembly and rebuilding?

And again, to clarify as you said, if nothing is found then the whole transmission needs to be removed to identify where the part came from.

Another thought that I had, who knows how long that support ring or that part had been broken.

I don't think I had checked the transmission fluid/pan since I changed it back in 2018. It's possible that that part has been lodged down there in the transmission pan area for a lot longer than just three weeks ago, and I indeed did just blow the governor solenoid.

I know that's a far chance, but if that's the case then I'm facepalming myself for not throwing the solenoid in there when I had the pan off the other night.

If the trucks has been running for a while with that broken part but the solenoid just blew out 3 weeks ago and all I need is a new solenoid then that's what I want to do for now, knowing that the transmission will still need work soon this year.

So that's where I'm at, I'm all for looking into the overdrive unit first to see if that's where the parts from, I'm also all for putting a new governor solenoid in there first to see if that clears up the code and gets me back on the road.

I can do the solenoid myself or with the help of a friend, the other though, that I need some help with and based on my conversations with auto shops in the area most shops want to do either a full rebuild of the transmission or a new transmission entirely.

I'm in the Northern Bay Area of Sonoma County if that means anything.

Again, thank you for all your guidance, I'm trying to be concise but thorough.

I'm on a budget but I want to get this truck going because I had started to schedule work for myself this year and then this happened.

Let me know whatever you feel, everything you've helped me with thus far has helped me advance towards a solution I really appreciate it!

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Saturday, January 15th, 2022 AT 8:15 PM

JACOBANDNICKOLAS

MECHANIC
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First, you are very welcome. The idea that the shops want to rebuild it really isn't a bad idea simply because once it is apart, it is easy to replace components. If you have a reliable transmission person, that is what I would recommend.

If you have a chance, let me know how things turn out for you. I'm interested in knowing. Also, let me know if I can help in any way.

Take care of yourself,

Joe

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Saturday, January 15th, 2022 AT 9:45 PM