[watchdog]

I have a 2008 F350 crew cab, LB, with the 6.4L diesel engine. It has a Dashdaq programmer running the recommended tune for best fuel mileage and DPF/EGR delete. It is actually getting 17 MPG consistently with 1000lbs of tools and fiber glass cap on back. Recently it started throwing a P0740 TCC DTC. I checked the undercarriage and electrical connections and all is spotless and clean. I removed the connector on the drivers side top of the transmission above shift linkage and the clip broke when I removed it. I contacted the local ford dealer to discuss replacing the broken plug and was advised to zip tie it on and it should work fine. I cleaned the plug that already appeared clean with contact cleaner and a soft tooth brush. Reinstalled and zip tied it down tightly. This seemed to improve the shift and feel of the truck and definitely delayed the reoccurrence of the issue after deletion of the code from the ECM. When the code reappeared it had a friend P1744. I then drained the trans fluid which was dark but did not smell burned and the pan was spotless, no metal at all. I replaced the TCC solenoid, pan filter and refilled with the required Mercon LV Fluid. I can now drive the truck, up to a day or so and if I do not use cruise control, and I guess I have learned how to feel when it is about to throw the code and I back out of the throttle a little and it prevents the issue. What should I do next vs. giving up and taking it to a transmission shop? I have addressed both of the issues that the codes direct you to do.

 

[Mark Kovalsky]

I removed the connector on the drivers side top of the transmission above shift linkage and the clip broke when I removed it.

That's the turbine speed sensor. Why would you look here for that code?

The ONLY way that P1740 can set is if the TCC solenoid doesn't move when the PCM tells it to. Bad wiring cannot set this code.

When the code reappeared it had a friend P1744.

That code just means the converter clutch didn't apply when the PCM told the TCC to lock the clutch. Since we already know from the P1740 that the solenoid doesn't work, this code is no surprise. It does take more occurrences of the problem to get P1744 to set than it does to set P1740.

I replaced the TCC solenoid, pan filter and refilled with the required Mercon LV Fluid. I can now drive the truck, up to a day or so and if I do not use cruise control, and I guess I have learned how to feel when it is about to throw the code and I back out of the throttle a little and it prevents the issue. What should I do next vs. giving up and taking it to a transmission shop? I have addressed both of the issues that the codes direct you to do.

If you replaced the TCC solenoid that should have fixed the problem. Either the wrong solenoid was replaced, or the new solenoid is defective. Once again, the ONLY way that P1740 can set is if the TCC solenoid doesn't move when the PCM tells it to.

Did you replace the one labeled TCC?