I have done more research on this and have found others that have had trouble getting the obdII 4l80e tcc to lock up by adding the ground switch to the brown wire.
I have read that you can make it work if you wire a 50 ohm resistor inline with a ground to wire #27 (trans fluid temp) on the red connector, but if you do that the trans will shift at full line pressure - and then you should shift manually to unload the clutches.
Another interesting note - I made this work on my obdII '98 s10 with the 4l60e, but that trans has 2 tcc solenoids listed - a tcc solenoid, and a tcc pwm solenoid. The 4l80e only has one tcc solenoid.
I have read that you can make it work if you wire a 50 ohm resistor inline with a ground to wire #27 (trans fluid temp) on the red connector, but if you do that the trans will shift at full line pressure - and then you should shift manually to unload the clutches.
Another interesting note - I made this work on my obdII '98 s10 with the 4l60e, but that trans has 2 tcc solenoids listed - a tcc solenoid, and a tcc pwm solenoid. The 4l80e only has one tcc solenoid.