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Tranny problem!!!!!!

16K views 33 replies 10 participants last post by  TransEngineer 
#1 ·
i got 2011 dodge ram 1500 whit 108xxxkm and week a go tranny just stop working now my computer give my those code

po944 loss of hydraulic pump prime
po734 gear ratio error in 4th
po871 od pressure switch rationality
po868 line pressure low

i need help i dont no i need to send my tranny to rebuilt or is just sensor or neutral swich ****
 
#2 ·
Sounds like you have lost all your line pressure (judging from the P0868 and P0944 codes).

1) Check the fluid level (idling in Park). Is it OK, or is it low? If low, fill it up. If HIGH (or OK), go to step 2.

2) If fluid level is good (or reads too high), then next most likely problem is a filter issue. Drop the trans oil pan and inspect both filters. Make sure the spin-on filter is snug (not loose, or laying in the pan). Do not overtighten it, just snug it up by hand like you would a spin-on engine oil filter. Check that the snout of the main (flat) filter is pushed up THROUGH the seal in the pump housing (not just resting against it). Check that the top of the filter is not cracked (look at the base of the snout), and that it is not split open along the side seam. Check that the filter seal (in the pump) is correctly installed. The metal flange on the seal should be FLUSH against the pump casting all the way around (not tilted in the bore). It is easiest to inspect this when the spin-on filter has been removed.

Also, check for clutch debris in the pan, and "metallic mud" on the pan magnet, while you have the pan off.

3) If the filters are all OK, and the fluid level is OK, then you likely have either a stuck main regulator valve (inside the pump), or a broken input shaft, stripped input clutch hub, failed torque converter, broken flexplate, etc. (all of which will require trans removal to inspect / repair). I would have it towed to whatever shop will do the work, and then have them check it with a scan tool (read the line pressure, turbine speed, and output speed with engine running and trans in Drive) to help determine (in advance) where the problem is.
 
#29 ·
Hey there TransEngineer,
I saw in a post regarding a loss of line pressure (P0944) that you were very knowledgeable on the subject. I’m looking for some guidance on an issue I’m having that’s a little unique.
I have a 2007 1500 which had a 545 rfe 4wd. That trans went out so I swapped a 2wd 545 in its place. I reused the 4wd torque converter, oil pan and installed 2 new filters, the spin on one and the flat filter for a 4wd. Took it for a drive, shifts fine, makes a slight whining noise (not entirely sure it’s trans or gear related) and also threw this code at me. Fluid level seems high but wanted to see if you any input before I pull the pan back off to inspect the filters. Hope this message reaches you. Thanks!
 
#6 · (Edited)
The Bible says, "...knowledge is easy unto him that understandeth." (Proverbs 14:6)

Even complicated things like transmissions can be simple if you understand the basic concepts and functions. I find that if you explain things so that people can visualize / grasp them (which is what I try to do), then even the non-rocket-scientists among us can understand!

Thanks for your kind words. I am blessed when I'm able to help others.
 
#8 ·
I think we ALL are the non-rocket-scientist type! I can't figure this stuff out, either, unless I get a clear enough picture in my mind to understand it.

Years ago, someone tried to explain to me the "tabular method" for calculating ratios, speeds, and torques of planetary geartrain components. I never could figure it out - it never made any logical sense to me. To this day, I STILL can't figure it out!! But I found another method, called the "lever analogy," that is simple enough to make sense even to me. I can UNDERSTAND the lever analogy, so now I use that method for geartrain analysis (and have for decades).

Anything is easy to learn, if you understand it. Similarly, it is difficult or impossible to learn something, if you don't understand it. So the key to learning is not how smart the student is... it is whether the teacher can explain things in such a way that the student understands it.

Lecturers who try to impress their audience with their knowledge (by speaking in unexplained technical terms that no one understands) are wasting everyone's time.
 
#10 ·
Hi Trans Engineer, I have a question for the expert, I can't PM yet so I am posting. I have an 03 Durango I did a 05 Ram Hemi swap into. It had the 4.7, I had a custom harness made by Hotwire and the ECU flashed to work with my body harness. Anyway, I updated the solenoid pack to the 05, and now I am getting the PO734 & PO700 codes. They are pending and don't go to an Engine Light until a long time. I also can get an EL and limp mode if I shift into 2 or L and drive 100 yds. Any thoughts on this? I even swapped the new solenoid pack out again with no change. Also got new governor and speed sensors, also no change. I find it a coincidence that it goes out at the motor swap but I do have more power. I have a deep pan and a shift kit, I ran a basic superchips before which I believe raised the line pressure and had no issues for yrs.
 
#11 ·
So let me make sure I understand...

Did you install just the 05 Hemi engine (using the existing 03 trans), and then also install a new solenoid pack into the trans?

P0734 is Gear Ratio Error in 4th, and that is the critical code. P0700 is simply a flag code that indicates that some other separate trans fault has been set, so it's secondary to the P0734 and can be ignored.

When you put it in 2 or L and drive 100 yards, what fault do you get? Still a P0734? That would make no sense to me, since in 2 or L it should never get to 4th gear (and you can't have a wrong ratio in 4th gear, if you're not IN 4th gear!).
 
#13 ·
OK, P0871 is an OD Pressure Switch Rationality fault. That means the OD pressure switch was in the wrong state (open when it should be closed, or closed when it should be open). In 1st or 2nd gear, the OD clutch should be OFF, so the OD pressure switch should be open. Since you set a P0871 fault, that means the OD pressure switch must have been closed (causing the fault).

Try this: Start the truck up fresh, shift to L, and see if you still get the P0871 fault in L. If so, try it a few different ways:
• Shift to L and just sit there, stopped, at idle, for a minute or so. Any fault?
• Shift to L, then gently accelerate to parking lot speed, and continue to roll along at like 10 mph or so (at little or no throttle). Any fault?
• Shift to L, and run at heavier throttle. Maybe find a steep hill you can climb up, where you have to open the throttle more than on level ground. Doesn't have to be high speed / engine screaming. Just more throttle than on level ground. Maybe set the parking brake partially, and drive 100 feet or so like that. Any fault?

P0871 is usually caused by either a wiring problem (bad connection somewhere) or a worn valve bore in the main valve body (usually at high mileage). I'm trying to use the tests above to determine which is more likely in your case. Let me know what you find, and we'll go to Step 2....
 
#14 ·
Awesome thanks I tried it in 2 and 1 (it's not L my mistake) but it didn't throw any codes in 1. But I tried it in 2 at 12 mph on pretty flat ground it threw the 871 code. Also this might mean something, it has 190K on the trans but didn't have issues necessarily right away when I swapped the motor but I didn't try the low gears for a couple hundred miles on the new setup. I am ready to try step 2. Thanks.
 
#15 ·
OK, this is pointing towards a worn valve body. But one more thing to try:
Start it up, shift to "1", then accelerate gently to about 15 mph (or higher). Cruise along at that speed (in "1") for a few seconds. If you get no fault, then shift to "2". Does the fault set as soon as you shift to "2"? If so, then I'd say replace the valve body assy.
 
#20 ·
A new (or reman) valve body should correct the P0871. The P0734 fault is another matter. It indicates a slipping OD clutch. It is possible that your OD clutch has been damaged (burned) due to the leakage at the worn valve body bore. If that's the case, the valve body alone may not fix the P0734. You would have to pull the trans, tear it partway down, and inspect / replace the OD clutch pack.

It is also possible that the P0734 was caused by pressure leaking out of the OD clutch passage (at the worn valve bore), so it may be that the new valve body will indeed correct the P0734 also. But I can't predict whether that will be the case or not.

My thinking would be this: You need a new valve body (whether the OD clutch is burned or not). So I would go ahead and replace the VB, and see if that fixes it. You can also inspect the pan and top of the valve body for clutch debris (while the pan and valve body are out) and get an idea on whether the OD clutch is distressed or not. If the new VB fixes everything, great. If you still get a P0734, well, you needed a new VB anyway, and now you'd need to fix the OD clutch also.

I'm hoping the new VB by itself will take care of everything for you.
 
#22 ·
Hi there, so I just installed a new sonnex valved valve body. It seems to drive much better now, more power down low at it isn't partially engaging another gear and the fan isn't roaring forever on takeoff from cold now either. I haven't checked the codes yet, ignorance is bliss! Thanks for your help.
 
#23 ·
Hi again. I still get the same codes and more. p0735 as well as p0734. I took it to the dealer I have a connection with and the said the clutches look good and the codes are these, p0700 and p1719 which is an unexpected shift event or something. Anyway they were under the impression that an 05 Hemi valve body is what I should try. They said the part numbers were different between 03 and 05 and that there may be a check ball or different valve in the 05? Seems weird as the guy that I got the sonnex valved VB from, sells it as an 02-08 or 545rfe full range years and motors. Any thoughts? Also the 2nd gear immediate light that comes on, he said goes away when it is turned off and restarted. So confused but hopeful since they say the trans isn't toast yet.
 
#24 ·
P0734 / P0735 typically means your OD clutch is on its way out.

P1719 is not a valid code that I recognize for an RFE trans. There is no difference in check balls between 03 and 05 valve bodies. The 05 VB will have a "quiet" solenoid module (so will the 03 service VB now), and that is not related to the gear ratio error fault codes.

I'm a little confused if you're getting a CEL in 2nd gear, since P0734 and P0735 get set in 4th or 5th gear (respectively), not 2nd.
 
#27 ·
You should always replace the filters when you change the fluid, whether you flush or not. I prefer to just drain and fill without flushing.

I believe the interval is 120,000 miles, or 60,000 miles for severe service for your transmission
 
#33 ·
Hey Transengineer,

I have a 2004 Dodge Ram 1500 5.7 l hemi 4x4 and I've got nine codes that popped up.
p0700 code for the transmission control system.
p1790 fault after immediately after shift
p0944 loss of hydraulic pump prime
p0868 line pressure low fall
p0731 gear ratio error in first
p0841 transmission fluid pressure sensor/switch "a" circuit range/performance
p0733 gear ratio error in third
p0736 gear ratio air in reverse
p0732 gear ratio in second
I have recently replaced the shift solenoid cuz originally I thought it was the shift solenoid so I fixed it replace the transmission filters the gasket the fluid still not running it wasn't running right I also put some Lucas transmission fix in it and it's still not running right so I was wondering what could be causing it I'm thinking the front pump possibly
 
#34 ·
Yeah, it looks like you have loss of line pressure. P0944 basically means you have no (or virtually no) line pressure. The usual culprit is a loose or misinstalled filter, but since you've apparently already replaced the filters (and I presume, installed them correctly) then yes, the pump is the next suspect. Actually, stuck main regulator valve (which is in the rear half of the pump). Sounds like it's time to pull the trans, check the main regulator valve, and probably inspect / replace the clutch packs while you're in there.
 
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