P0740 Error Code and Rumble Strip Noise after flat towing Jeep up steep grade

TROLL

2007 Winnebago View 23H
Earlier this year I purchased an 06 Sprinter (07 Winnebago View, actually).
The transmission was replaced roughly 40k miles ago with a rebuilt unit by Silver Star Transmissions. It drove well, although during the pre-purchase inspection the experienced tech could tell it had been rebuilt and was not an OEM unit due to some vibration he felt. It was subtle though and I never really noticed much.

Fast forward 6 months and I just hit the road, with a one-time flat tow of my 97 Wrangler from FL to CO. The route is mostly flat, except for a 6% grade over a pass in TN where I was maintaining about 45 mph over a 2300' rise in elevation.
Shortly after this climb I got a CEL with a P0740 error code and also noticed for the first time a "rumble strip noise" at a couple different spots in my driving. If I left off the gas or press the gas pedal in more it goes away usually. At one point it resonates very badly with what I think is the factory jack and makes a very loud rattling noise, but other times it just really does sound like I'm driving over the rumble strip on the side of the road.

I continued my drive to CO which was mostly drama free, except for the rumble strip noise and the CEL on the dash. I have not reset the codes yet, waiting to decide what my next move is. I do hope to continue driving this cross country though and want to try and avoid being stranded in the middle of nowhere! I do not plan to flat tow any more, but I do plan to drive in and out of mountain passes.

Not finding a whole ton of info on the P0740 code or what if any action I should take so figured I'd start a thread here and see if anyone had experience with this.

(Also have a recurring glow plug P0380 and P0671, and a new 02 sensor P2A00 code, but I don't believe any of these would be related).

Thanks!
Bryan
 
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Cheyenne

UK 2004 T1N 313CDi
Your P0740 code translates as 'Torque Converter Clutch Circuit/Open' so it may be time for a trans service as a starter unless anyone else knows more.

Keith.
 

lindenengineering

Well-known member
Most likely the torques converter solenoid is out, maybe the gallery pressure control solenoids as well!
A scan interrogation will show up what is working and what is not including pressures by looking at clutch pack fill time operation.
Dennis
 

NBB

Well-known member
The transmission was replaced roughly 40k miles ago with a rebuilt unit by Silver Star Transmissions.
Say no more. There is no such thing as a correctly rebuilt transmission. They are too complicated to rebuild in the aftermarket, and impossible without the full specs and tolerances and manufacturing procedures - which no OEM will provide to a re-builder - or anyone else.

Take good care of your OEM unit. If it fails, get rid of the entire vehicle, IMO.
 

ptheland

2013 144" low top Passgr
Are you still in Colorado? Dennis (Lindenengineering above) has his shop in the Denver area.
 

TROLL

2007 Winnebago View 23H
I took the vehicle to Linden in order to get the transmission codes so I had more info -- they scanned the vehicle and drove it and based on their diagnosis they recommended replacing one solenoid and the main board, plus a fluid change in the process. Labor was $450 and parts were about $750. Unfortunately I didn't get the actual transmission codes from them which kind of defeated the purpose of my trip, but I didn't specifically ask for them before I left so I'll take responsibility there.

I haven't done anything as I shifted my focus to a coolant loss issue that has led me deep into a head gasket change and head repair. Before I started that I had the vehicle at the MB dealer and they scanned and I guess cleared my codes. The tech said he didn't notice any vibration from the transmission. When I got the vehicle back the codes were cleared and I don't notice any vibration from the transmission either. Strange... but at this point I plan to do a fluid change because its about due, and hopefully the vibration and CEL won't come back. They probably will though, and I'll just have to address it when they do.
 

TROLL

2007 Winnebago View 23H
Update with good and bad:

Had my vehicle at the MB dealership for something totally unrelated, and they told me they cleared my codes while it was there. I asked the tech if he noticed the vibration from the transmission and he said no. When I picked it back up there was no vibration. What? There was a clear and definite vibration previously at light throttle between 1500-2000rpm but now it was gone.

Is it possible that the MB dealership did some sort of ECU reset and that the vibration was caused by ECU learning which got wiped out when they reset it? Are there any other guesses as to why the problem would go away fully after a visit to the dealer?
After the dealer visit I did a service on my transmission and even checked and cleaned the valve body, speed sensors, and solenoids just in case. I used Shell 134 ATF. For the next couple thousand miles I still had no vibration and no CEL, until...

Fast forward about 5k total miles since the visit to the dealership (CO to AK, and about to head back south again), and the vibration has slowly come back over that time, and gotten worse. It is now pretty frustrating and annoying and loud, and is not allowing me to drive with a smooth throttle as I have to either get off the throttle or push through the vibration to get past it. Is it possible that ECU learning has taken back over and is resulting in this issue?

How can I diagnose what the heck is going on? I really wish I had the transmission codes from my visit to Linden but I didn't ask for them specifically and they did not put them on my paperwork. I have ordered an Autel AP200, not sure what its capabilities are but I'll have that next week. Any other suggestions or ideas? I would LOVE to fix this. Thanks!

p.s. took a couple videos of the issue, in case anyone is interested in having me send them to you.
 

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