P1740 with no TCC lock

[IBMobile]

     In March the transmission had a no or delayed 1-2 and 2-3 shift condition.  The transmission and cooling lines were flushed,  the 3-4 accumulator spring, along with the governor solenoid and pressure/temperature transducer replaced.  The fluid was changed to Valvoline synthetic +4.  The transmission shifted great after the repair.  

 

     The end of July I go on a 1000 mi "camping trip" pulling my 5th wheel with the boat behind it.  I find out that I have no torque convertor lock up! This had happened once before in May of 2018 for about 10 miles.   Now, cruising at 60 mph the RPMs are1900±;  when accelerating from 60 mph the RPM increase rapidly to 2400-2700 depending on the load and peddle position;  when the accelerator peddle is released at 60 mph the RPMs drop to 1400.  The transmission temperature, measured in the cooling line between the pump and engine coolant heat exchanger, is normally 160-170° but with no lock up the temperature is 190° ±100°.  When going up long grades the temperature climbs rapidly and when it reaches 240° I pull off the road, put the transmission in neutral with the engine at idle, and after 15 minutes the fluid cools to 190° then I can finish the grade.   

 

   At 60 mph with the 'Mystery' switch on the RPMs still increase rapidly when accelerating indicating the torque convertor is not locked; when the accelerator peddle is released there is a drop of only 50 RPMs and there is engine breaking going down hills but the truck can come to a full stop in 3ed or 4th lock up, with the switch still engaged, and the engine will not stall.  

 

The fluid is still clean and full, the APPs in live data shows good with a smooth 0-100% transition and AC voltage is at .03v ±.005.  Ohm testing the solenoids shows: 3-4 shift solenoid 32.8Ω, TCC solenoid 32.8Ω, and the new Borg Warner governor solenoid 6.2Ω.  

 

What I'm thinking is either a lose of pressure to the TCC, a poorly opening weak solenoid,  or a bad TCC.    

 

 

[Bullet]

I was going to say probably a bad torque converter.  Lockup solenoid sounds OK but possibly a bad connection at the lockup solenoid?

 

Here's a pretty good diagnostic write up on here by our fearless leader...

 

 

Edited August 11, 2019 by Bullet

[JAG1]

I hope Dynamic jumps in to offer some information.

 

Dan did everything get replaced in the clutch pack on its first rebuild, just a few years ago wasn't it? And you only have a little over a hundred thousand on the entire truck. This gets me to thinking/ hoping its something simple. 

 

Looking at his Website, he's got some nice builds for 35-36 hundred. I think that's if you do the R&R then shipping on top of that. I would rather have Dynamic do everything on it. 

Edited August 11, 2019 by JAG1

[IBMobile]

On 8/11/2019 at 1:34 AM, Bullet said:

Here's a pretty good diagnostic write up on here by our fearless leader...

Thanks,  I pulled that up when I got the code and most of it deals with the overdrive which in this case works fine.  

Ohm testing from pin #87 of the transmission relay to the PCM shows the wiring is good and when the TCC solenoid is grounded going down hill I feel the TCC lock up.  

 

I'm starting to wonder if running 100% +4 synthetic fluid is causing the TCC to slip since this started after flushing and replacing the fluid

[Mopar1973Man]

On 8/10/2019 at 11:23 AM, IBMobile said:

the truck can come to a full stop in 3ed or 4th lock up, with the switch still engaged, and the engine will not stall.

 

TCC is shot in the torque converter. That should not happen. 

 

On 8/11/2019 at 6:40 AM, JAG1 said:

Looking at his Website, he's got some nice builds for 35-36 hundred. I think that's if you do the R&R then shipping on top of that. I would rather have Dynamic do everything on it

 

@Dynamic does awesome work and everything is absolutely spotless and clean. His rebuilds are absolutely worth the price. I got the 46RE rebuilt and upgraded to be more like a 47RE. Upgrade both the direct clutch and the overdrive clutch. Added the oil cooling holes to spray ATF on the clutch packs. Modified the valve body to have firm shifts and upgraded all the other stuff like the levers for the bands. 

 

[Dynamic]

P1740 is a performance code, meaning that the PCM is commanding something, and then not seeing the desired results. You don't mention any circuit codes, so I'm guessing that the PCM is happy with the integrity of the circuit electrically. In light of that, I would suspect that your converter clutch has failed. It is not at all uncommon.