Odd transmission behavior

[RDThompson]

I have an '08 6.7 with a 68RFE with roughly 112k on the clock. Recently there have been a few instances where the transmission suddenly forgets how to shift up or down. If I pull over and stop and then shut off the engine, everything is right as rain once I restart. There have been no hi temperature events, the transmission oil is up to the correct level and is reasonably fresh. I should add that no codes are generated at any time during these little Transient Ischemic attacks.

Has anyone else experienced these events with their truck?

 

[Kads]

Mine will shudder between 40mph and 45 when driving through town slow .. If I get on it a little and go faster between gears no problem. Some have told me, to use the paddle shifter and drive through town with it locked in 4..

 

[RDThompson]

That's pretty much the way I use my truck. 4th gear with the E/B on. I have only encountered the shuddering effect when I was on and off the accelerator or just lightly resting on it while decelerating. But that's my fault, it gives the computer conflicting data.

 

[transe]

Bob, if your transmission is not shifting, then it sounds like you are in limp-in. If you come to a stop, does it stay in 4th (direct) gear, so it feels really sluggish? Or does it launch normally in 1st gear, but then shifts directly to 4th (and stays there until you come to a stop again). I presume no CEL? Does the cluster display show "D" or "4"?

 

[RDThompson]

You are correct sir. When the trans is acting up it stays in 4th and also drives like I'm starting off in 4th no shifting at all. No CEL or codes stored. Display shows 4th usually but shifting the gears manually has no effect. I wonder if it's losing communication with the engine and has no tach signal to tell it where it should be. I have only had three events withthis problem so far. The first was about two weeks back. And of course shutting down and restarting clears all issues.

Bob, if your transmission is not shifting, then it sounds like you are in limp-in. If you come to a stop, does it stay in 4th (direct) gear, so it feels really sluggish? Or does it launch normally in 1st gear, but then shifts directly to 4th (and stays there until you come to a stop again). I presume no CEL? Does the cluster display show "D" or "4"?

 

[transe]

Definitely sounds like limp-in, then. But no codes? Not even a P0700? Are you able to read codes from the TCM, or just from the ECM?

Could be a problem with the trans relay (or wiring from there to the trans). That provides the main 12V power feed to the trans. If you lose the 12V power feed, trans will be stuck in 4th all the time (when in Drive). But if the TCM detects a problem and commands limp-in, it turns the trans relay off (and should set a fault code!). So no 12V power to the trans could also be (and usually is) just due to the TCM commanding limp-in. I would double-check for codes in the TCM.

 

[RDThompson]

I don't presently have a device to read the TCM so I will have to go to someone who does. I will report back once I have an answer.

 

[RDThompson]

I took the truck over to a friend who possesses the full monty of diagnostic scanning capability. He found nothing , not a sausage. He said one clutch pack was nearly but not quite out of the nominal value but then he reset it and it returned to a suitable number. We have examined and probed all cables and connectors linking the engine and trans without finding any anomalies.
We have decided that I should contact a Tarot reader or perhaps a native Shaman for further consultation. In short I suppose it doesn't warrant fretting about until it does something quantifiably measurable. I can simply hope smoke and or flames are not involved.

 

[transe]

I would expect, then, that you've simply lost the main 12V power feed to the trans (although I never have understood why this doesn't cause faults in the TCM). This power comes from the trans relay (located in the Totally Integrated Power Module [TIPM] or Power Distribution Center [PDC] - these are both the black boxes near the battery that contain fuses and relays, why there are two different names [depending on model / model year] I don't know). It goes to pin 10 on the trans solenoid connector, and is also fed to three different pins on the TCM. You can find wiring diagrams and connector pinout information at rambodybuilder.com.

So I would check for 12V on that circuit when the problem occurs. If no voltage, then I'd say you probably have a bad trans relay or TIPM/PDC or you have a wiring problem in that circuit. In some trucks, the trans relay can be replaced individually. In others, it is built into the main TIPM/PDC circuit board, so you'd have to get a new TIPM/PDC (probably a junkyard would be your best bet).

 

[RDThompson]

Thanks, I know which boxes you are referring to and I'll have a look. It makes a certain amount of sense as a scruffy contact can start off making a complete circuit but ibration and heat may have a poor effect and cause the contact to fail until it is cleared by shutting down and restarting. I appreciate your assistance and I will post any further information that emerges from this issue.

 

[Alan Reagan]

I agree with TransEngineer on the relay. Sounds like the relay may be sticking or have burned contacts.

 

[RDThompson]

I will check on that as soon as I return home.

 

[JConquest]

I experienced some transmission issues on a recent trip. 2010 RAM Laramie has 109 K. After unhooking the Travel trailer, noted issues when transmission was up shifting into higher gears and specifically some stuttering when trying to come into 6th gear. Fluid levels and quality appeared to be great. Truck towed quite well with the trailer coming home, but the last 100 miles was not fun. It locked into 4th and I had to pull over and turn the truck off and it reset on restart. I always use the tow/haul and constantly monitor trans. and coolant temps. Code light came on and then would go off. Fortunately it was on when I took truck to the dealer. Dodge recommended possible cracked or clogged filter. $300 later that was not the problem. Reputable shop then diagnosed that problem was slipping in 2nd. Going in for rebuild tomorrow.

 

[RDThompson]

The General consensus on mine is that I have a valve body that is in need of replacement. The P0871 and P0700 codes that I get when it acts up indicate a pressure sensor and a couple valve solenoids. So I am awaiting my window at Jerry's in Norwalk. I'm going to have him do a few improvements while he's at it. The guy is a wizard with transmissions. I know I could change out the valve body myself but my labor rate is higher than his and I'd still have an unimproved valve body.

 

[JConquest]

68RFE_ Just went through similar issues including replacing filters with no resolution. Just picked up the truck last evening from the local TRANCO shop. The culprit was one of the seals had failed allowing transmission fluid to freely flow through the transmission. Result was damaged clutch packs serviced by the culprit valve about the size of a quarter. Nearly $4 K later, it seems to be working fine. Upgraded components were installed. Shifting is extremely smooth after that fix.