If you wire in an electrical switch to close the brake light circuit, it will cause the PCM computer to unlock the torque converter clutch, even if the throttle is still depressed.

This trick can be useful on the highway when climbing hills that are just a bit too steep for Overdrive 4th gear on the 46 trans.
If you very lightly touch the brake pedal to trigger the brake light circuit only and not apply any real braking pressure,
the TCC will unlock
RPM will increase by about 300
and the torque multiplication of the slipping converter will sometimes be enough to avoid a downshift to 3rd gear.

I notice that on several newer 2004+ Chrysler vehicles the PCM computer is programmed to do it this way instead of downshifting.