That's a switch for the lockup torque converter clutch. It's wired in series with a pressure switch on the valve body that needs a particular governor pressure to complete the solenoid circuit and put the converter into lockup. High vacuum+correct governor pressure=lockup. Slow down, or step on the gas, and the converter clutch unlocks. It should work in both direct and OD if the right conditions are met. There are four modes: 3rd. gear unlocked, 3rd. gear locked, 4th. gear locked and unlocked. If it locks up too soon and shifts up and down too much, install a higher pressure governor switch. The pressure roughly corresponds to MPH- - - -45 lb. switch=45 MPH, etc.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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