Control circuit high actually means that the solenoid is stuck open, could be because broken tube. The way that works is the solenoid sends a high when it is open and a low when closed, if it sends high when the TCM expects it to be low the code sets. The 1-2 solenoid is normally open.
Another of those pesky names that don't exactly mean what you think.

 

Huh. Live and learn. I thought it was a dumb solenoid with just 2 wires. Must be more to it than that. How does it "send" a signal? I would expect you could test the coil resistance. A shorted coil would be below the resistance range, circuit would be high voltage. An open coil would be very high resistance, circuit would be low voltage. Or something like that. I might have it backwards, depending on where you measure.

 

It is in the shop manual link in my sig.