Hello everyone,
I’m struggling with a strange shifting issue on my 2006 Super Duty with the 6.0L PowerStroke and the 5R110W TorqShift transmission. The truck has 160k miles on it.

I am experiencing a random, intermittent hard shift into 3rd and 5th gears. Has been doing it for years. There are no active DTCs or Check Engine/Tow-Haul flashing lights.
In an attempt to fix it, I recently installed a set of MTS high-pressure solenoids. Unfortunately, this actually made the hard shifts worse and more violent when they happen.

While monitoring live TCM PIDs using FORScan, I noticed something unusual. The PID TCC_OT (Torque Converter Clutch Over-Temperature Lockup Mode) reads "Fault Present / ON" constantly.
It is triggered the absolute second the truck is started up cold first thing in the morning. However, my actual Transmission Fluid Temperature (TFT) PID reads perfectly normal and matches ambient temperature when cold, slowly warming up to normal operating temperatures.
My Questions for the Experts:

1. Does a constant "Fault Present" on the TCC_OT PID point toward an electrical short in the internal wiring harness, a bad sensor, or a glitching TCM?
2. Could a falsely triggered TCC over-temp strategy be altering line pressures and causing my erratic, harsh 3rd and 5th shifts?
3. Given that the MTS high-pressure solenoids amplified the issue, I am pulling them back out and go back to stock Ford OEM solenoids once the underlying electrical issue is found.
4. I have B1352-20 Ignition key in circuit fault
5. P1876 Transfer Case 2-Wheel Drive Solenoid Circuit Open Or Short To Ground
   
   P1832 Transmission Transfer Case 4WD Solenoid circuit failure
   
   P1820 Transmission transfer case low to high shift relay coil circuit failure
   
   P1828 Transmission transfer case high to low shift relay coil circuit failure
   
   The driver battery is grounded to engine and battery voltage is good.
   

Any insight into how to properly diagnose this TCC_OT fault or what pins/wires I should be testing would be greatly appreciated!
Thanks in advance!

AI says to check for a shorted wire in the transmission harness or a corrupted TCM strategy but need some pointers. I do have HP Tuners MPVI4 but not good at it.

 

Maybe it’s just a Forscan glitch. I’ll have to check it with another code reader.

 

I cleared all the codes and the only one to return is b1352 -20 Ignition key in circuit fault. The 4x4 low took multiple tries shifting R-N-D and several minutes to get it out of low gear. I installed a new switch not the key tumbler and it is still present. The 4x4 doesn’t lock in with esof but can manually. I’m going to check for vacuum leaks in the system. I did the ATSG recommend for relearn. "Engagement Schedule" must be updated. For the trans.

This procedure will prevent the customer from

returning with firm or harsh engagement

complaints.”