O.K. So far I have found out it is for a converter lock-up and only two leads are used. Looking at schematics on line I see options using vacuum, pressure or brake light circuitry to kick it out... Which is preferred by you guys with the first hand experience? What happens if I just put in a cover plug and don't add the switch?
Still confused but learning...
I think no matter what you do for lock up engagement a switch for the brake pedal is a good idea. In the event the rear brakes do lock up the rear wheels, better to not have the torque converter lock up clutch engaged.
I have a butterfly switch on the shifter to manually engage the converter clutch. I never had any luck with the vacuum switch. It always made the converter lock up at the same time as the 4th gear shift. I've never tried using a vacuum switch in anything other than my daily driver. I wonder if a shorter duration cam with a higher vacuum signal was what made the vacuum switch ineffective for me. It seemed like I either got lock up with the 4th gear shift, or not at all. It could be that I may not have been using a vacuum switch with the correct range or the range on it had a sensitivity that put me in an "all or nothing" outcome. It could be that my 3-4 shifts all occur under light throttle where a strong vacuum signal is present. I never figured out how to make it work correctly no matter how I adjusted the switch.
If anyone found a switch that behaves pretty well, I would certainly like to know what they are using. The idea of lock up at light throttle and unlock when opening the throttle in 4th gear would be ideal. I've had the switch on the shifter set up so long now that it's habit and I don't even think about it. I only use lock up on the highway. City driving is when I have it turned off. I flip the switch when I get to cruising speed on the highway.
If you just plug the hole and deactivate the torque converter lock up, you could just install a non-lock up converter. You wouldn't have the benefit of the lock up from a fuel mileage standpoint. It would also cause a rise in transmission temperature compared to the lock up in 4th gear at highway speed. The extra heat could be mitigated by using a larger cooler as a stand alone or a larger auxiliary cooler. You can get a thermostatically controlled bypass for whatever cooler set up you have, if you had concerns about running the transmission too cool. That would be more dependent on driving conditions and what temperature weather you need to have considered.
) but now I am wondering where the 4 leads go to? I'm sure Speedway or somebody will have the mating connector but can someone direct me to a schematic that will show the connectivity? 
