I've read about all the posts here about this code after getting it a couple times this week. If I clear the code I'm fine until get up above 45mph when the lockup kicks in and then unlocks when I slow down. Shortly after, SES light comes on and I'm in limp mode again. Here's what I have:
2002 Camaro LS1 retrofit into a 58 Apache. 4000 stall, 3.90 gears, 228r cam on 114. I've had a tuner work on this setup and he took care of the basic stuff, runs and drives great. I started playing with the shift points a bit, nothing crazy and mainly just part throttle stuff for around town. I had P0757 before the tuner did his thing, but after it was gone for quite a long time. Then after my last edit it started popping up. (I think perhaps prior to the tuner I was getting P0757 as a result of MAP/MAF codes that were setting limp mode.)

So I'm going to try going back to my previous file and see if that fixes it. Otherwise my tuner said I could disable that code safely.

My questions are...

1. Has anyone figured out how to tweak the setup so that P0757 won't set with with high stall cars without just disabling the code? Just thinking it might be good to have it in there but just make the pcm less sensitive to the conditions that set it.

2. If you do disable the code and there is actually a problem with the solenoid, what would you notice so that you could baby the car home and take corrective action?

 

I disabled mine. For me, it threw the code sometimes. Then I figured out why, and made it predictable. So technically I could drive around the code and avoid it, but I deactivated it anyway. A shift solenoid code monitors if the solenoid is working, meaning did the transmission shift appropriately when commanded. How does it do that? By looking at input vs output speed during and after a commanded shift. The computer is looking for a reduction in input speed corresponding with an increase or equal output speed. Meaning by going up a gear the motor rpm reduced and the driveshaft stayed the same or kept accelerating. It doesnt monitor this at all times, just very near the commanded shift, say 5 seconds. Picture a big converter being driven, light throttle, shift, then right after the shift the driver adds 25% throttle, the extra load of the higher gear will cause the stall to flare some. The computer reads this as a direct shift fault because according to the program the shift didn't happen correctly due to the input and output shafts speeds not corresponding. Makes sense. The trick for me was, dont add throttle for at least 3/4 seconds following an upshift. That's all it took to avoid limp mode.

 

If you "feel" your car at all and know even very approximately what speeds correspond to what RPM, you will know if a shift solenoid fails.
Lots of people with high stall converters disable the code; perhaps surprisingly I have not had to.