Good day! Trying to keep this as short as possible. 04 FX4 5.4 3V with a 4R75E transmission. A year or so ago it began shuffling between 1st and 2nd instead of a firm shift. It threw a P0750 code so I replaced the solenoid pack. No love. I then replaced the valve body because I found a slight crack when I replaced the solenoid pack. Still no love. It eventually fried first gear so we bought a reman transmission from O'Reilly Auto Parts and had a certified Ford mechanic install it. It did fine for a few months, but now, it's back to the same issue. I've checked the solenoid A wire for continuity... good. Checked it under load for voltage drop... good. Checked it for a short to ground... good. I'm at a loss! Can someone please help?

 

Welcome to the forum. Not sure if you changed font color on your photo but this is what it looks like on mobile for me. Lol.

 

I copied and pasted from another forum I posted it on. See if this is any better...

Good day! Trying to keep this as short as possible. 04 FX4 5.4 3V with a 4R75E transmission. A year or so ago it began shuffling between 1st and 2nd instead of a firm shift. It threw a P0750 code so I replaced the solenoid pack. No love. I then replaced the valve body because I found a slight crack when I replaced the solenoid pack. Still no love. It eventually fried first gear so we bought a reman transmission from O'Reilly Auto Parts and had a certified Ford mechanic install it. It did fine for a few months, but now, it's back to the same issue. I've checked the solenoid A wire for continuity... good. Checked it under load for voltage drop... good. Checked it for a short to ground... good. I'm at a loss! Can someone please help?

 

One other thing... it only has the problem at lower rpms. When accelerating rather heavily, it shifts like a dream.

 

Very weird. It sounds like some sort of TCM related issue to me? Since one did it, then the other. Although not right away, so it's not quite cut and dry.

 

When I get time, I'm going to check the resistance across the solenoid. If it's bad, I'm going to replace it and the PCM. That's all I can think to do.