I just finished rebuilding a 4L60E with a Hays 3/4 Twister torque converter for my Chevelle. Other than lockup the transmission works great.

I did not remove the pan yet, but I did connect a switch to enable/disable the TCC. The switch also has a LED, which I ran in series with the TCC solenoid. When the transmission shifts into 4th gear, the LED lights, so I know the pressure switch is working and current is flowing through the solenoid.

Unfortunately, I don't notice anything when switching the TCC circuit on/off while cruising in 4th gear. I'm assuming there would be a slight change in RPM when the clutch engages/disengages. Other than pulling the torque converter, is there anything else I can look for in the valve body or the valve under the solenoid?
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