98 Jimmy OBDII TroubleCode P0740

Trouble code P0740 (Malfunction in electrical circuit for the Torque Converter clutch) coming up with scanner. Tranny slipping occasionally when braking hard to stop and jumpy rpm's when that happens but other than that no issues. Anyone else having/had this issue? Any remedies/suggestions?
I have searched and found a few notes here and there but no specific resolution. Thanks for any help or thoughts.

Found a description for you of the TCC and GM has had some problems with the TCC in the trans but I think (not a trans expert) that this is a wiring (internal or external) problem as no voltage detected. Any trans work done on this recently - may have caused it.

Circuit Description
The torque converter clutch (TCC) solenoid valve is a normally-open exhaust valve that is used with the torque converter clutch pulse width modulation (TCC PWM) solenoid in order to control fluid acting on the converter clutch apply valve. The TCC solenoid valve attaches to the transmission case assembly extending into the pump cover. When grounded (energized) by the powertrain control module (PCM), the TCC solenoid valve stops converter signal oil from exhausting. This causes converter signal oil pressure to increase and move the converter clutch apply valve against spring force and into the apply position. In this position, release fluid is open to an exhaust port and converter feed fluid fills the apply circuit. The converter feed fluid applies the TCC. When the PCM no longer provides a ground path, the TCC solenoid valve de-energizes and apply fluid exhausts, releasing the TCC.

No recent work done. I took it to a shop and they said they weren't sure and wanted about $550 to crack open the tranny and replace the solenoid. Which if thats the issue then I'll get it done but don't want to shell out that kinda money and still have this issue so I was just seeing if anyone else out there had any similar issues.
Thanks for the reply and additional info.