2009 ram 1500 P0841, P0935

[Jgarlock92]

Hello, I know this is a common issue but I wanted to see if anyone had any ideas I haven't came up with yet.

I have a 2009 ram 1500, 5.7, 4x4.

The transmission starting dropping into 4th gear anytime I try to move the vehicle in drive, if i drop it into first manually I can go about 3-5mph without issue, but accelerating past that or trying to shift up into second will cause it to go back into limp mode/4th gear and stall out. The only code I have at the moment is P0841, which is L/R pressure switch rationality from my understanding, however I have a cheap code reader right now.

Reverse seems to function normally, I do not feel any delays when shifting into either reverse or drive either.

About a year and a half ago the TIPM was replaced with a unit from MAK's, and about a year ago I replaced the solenoid pack on the valve body.

I dug back into it this weekend and found 5 bolts on the valve body, not the ones holding on the solenoid, were loose, not finger loose but definitely not torqued by any means. I removed the assembly, retorqued everything, and reassembled with new fluid in hopes that was the issue. I also replaced the transmission line pressure sensor while I was there.

I did not remove or check the spin on filter, as it was installed a year ago, although i likely should have from what i have read. The other filter was in perfect shape and the seal looked fine.

There was no debris in the pan, honestly as close to spotless as I have seen, and next to nothing but a light coating of dust on the magnet.

After reinstalling everything, and checking the fluid, it is sitting right at the low mark on the hot side with transmission temperature at 160*F, which seems to be just about perfect from what I can find looking at charts. It was checked on a level surface, in neutral, after letting things warm up.

My plans for next steps are as follows

1) I have a better code reader showing up today to check and see if there are any further codes, and to check what the system says the transmission pressure is.

2) Swap the wires for 14/15 in the main 32pin transmission harness, this is where i could use a bit of advice as well, I believe both of these go directly to the C4 connector on the PCM before anything else, is this correct? does anyone have a diagram? I have been unable to find an exact diagram for 2009 and am hesitant to swap wires without knowing precisely that they are the correct ones.

3) I have a new valve body gasket set by transtec coming on Wednesday, when that arrives I plan to drop the pan, disassemble, clean, and reassemble the valve body with the new gaskets, and reinstall. I will also replace both filters again this time.

4) If the issue still persists, I plan on getting a pressure test kit and checking the port pressure on the transmission to see if it matches up with what my reader is showing me. If it does not I would assume the PCM has gone bad.

Just want to check if anyone has any other suggestions or comments on things, I have rebuilt multiple engines and done some wiring, but I have only worked on transmissions a few times and want to make sure I am not missing something obvious.

 

[Jgarlock92]

Just for anyone who might pop by, code reader is showing reference numbers not actual pressure, but getting both p0944 and p0945 , low and high from the same sensor so I’m assuming wiring. Will check further tonight

 

[Jgarlock92]

So I’m assuming pin 2 and 3 are shorted together somewhere along the way, the ground seems fine, and neither are shorted together ground, but both the 5v supply and the transmission line pressure signal have 5v, if I wiggle things around the line pressure signal varies.

Going to run new wires for the 5v supply to pin 27 on c1 and the signal wire to pin 31 on c4

 

[Jgarlock92]

update, ran the new wires and I am still getting a solid 5v to both 2 and 3.

Just to check, am I correct in thinking that I should only have 5V going to 2, and no voltage going to 3 when the wiring harness is unplugged from the sensor?

My understanding is that you have your ground, 5 volt coming from pin 27 to pin 2, and then the pressure sensor adjusts that 5v and sends back anywhere from .35 to 4.75v to the PCM pin 31.

If this is the case, and I am not incorrect, I would assume the PCM has failed in a way where it is incorrectly sending 5v from pin 31 on C4.

I have attached the wiring schematic I am looking at just for reference.

 

[Jgarlock92]

Further update, I was in fact incorrect, pin 31 at the pcm produces 5v when the wiring harness is disconnected. When connected it’s reading within range. I’m assuming this is a fail safe so if it the pressure sensor fails it’ll throw itself into limp mode.

So wiring, pcm and sensor seem to be doing what they should.

I ordered the OBD link cx which apparently does not work with Alfa OBD on windows, so I’ll be getting the mx+ today and checking pressures.

Tomorrow I am likely dropping the pan, disassembling, cleaning, and reassembling the valve body with the new upgraded gaskets, and replacing filters. As well as trying to do some further testing on the solenoids.

 

[Sherman Bird]

Is this trans a 545RFE? Or a 722.9?

 

[huntergreen]

I’m not much of a mechanic at all, but I’d replace the valve body with the sensors. Also , was there much debris in the pan ?

 

[Jgarlock92]

Is this trans a 545RFE? Or a 722.9?

545rfe

 

[Jgarlock92]

I’m not much of a mechanic at all, but I’d replace the valve body with the sensors. Also , was there much debris in the pan ?

No debris at all really, solenoids were replaced about a year ago, plan on dismantling, testing and reassembling the valve body with the upgraded gasket set

 

[Sherman Bird]

545rfe

The valve body gaskets are an aftermarket add on to address case warpage. The Transgo shift kit is a VERY wise improvement along with those gaskets!

 

[Jgarlock92]

No debris at all really, solenoids were replaced about a year ago, plan on dismantling, testing and reassembling the valve body with the upgraded gasket set

Also ohmed out the solenoids and all seems okay, but will double check

 

[Jgarlock92]

The valve body gaskets are an aftermarket add on to address case warpage. The Transgo shift kit is a VERY wise improvement along with those gaskets!

I’ll look into that!

 

[huntergreen]

No debris at all really, solenoids were replaced about a year ago, plan on dismantling, testing and reassembling the valve body with the upgraded gasket set

Did you replace with mopar solenoids? Many have posted aftermarket have a high failure rate.

 

[Jgarlock92]

Did you replace with mopar solenoids? Many have posted aftermarket have a high failure rate.

Honestly, I am not 100 percent positive. I believe I ordered a rebuilt oem unit, but I don’t recall where from.

I believe I can test the individual solenoids using Alfa OBD? Other than that is there a better check than just checking resistance at the pin out

 

[Jgarlock92]

Did you replace with mopar solenoids? Many have posted aftermarket have a high failure rate.

Update, tracked down the order and the replacement was a new unit from wells off rock auto

 

[Sherman Bird]

Update, tracked down the order and the replacement was a new unit from wells off rock auto

Wells is an Auto Zone product, If I recollect properly. I've seen nothing but troubles with that brand spanning over 30 years. As a professional, my perspective is definitely different from the DIY'ers here. BUT, I've had MANY vehicles towed/brought in that I fixed merely by replacing Wells' products with OE (preferred) or higher level aftermarket parts.
I'm not intending to poison the well, so to speak about AZ or Wells, but, since I've seen such consistent failures, I believe it to be fair to call a spade a spade.

My advice is for you to go on TranStar site and order through them. I am a professional Automatic Transmission technician and can attest to the fact that, as an aftermarket supplier, TransStar has really exceeded most others in the category of high quality!

 

[Jgarlock92]

I appreciate the input, I will remove it and double check all the solenoids, I am assuming at this point that the pressure control solenoid is likely having an issue.

If so, it is still within warranty, I may warranty it first as long as it's a reasonable timeline, and if the new one starts having issues I will go through Transtar. We just purchased a new house within the last month, so I have to try to minimize expenses on this as much as possible for the time being!