Hair falling out

Been searching half the day, eyes hurting and patience growing thin. And I finally think I have it down. 1992 700r4 with 6.2. This is a 3 pin connector.

Very simple. I want lockup around town and on the highway. But will use a dash switch for steep hills and heavy stop and go traffic to keep heat/cycling down.

-Purple wire is 12v in.

-Blue wire sends signal to the ECM (not applicable here) to tell it was in 4th lockup. THIS WIRE IS NOT USED RIGHT?

-Tan wire is ground and is where you place your toggle switch

Do I have everything correct?

Success! Information confirmed by a very knowledgable member from another board. To get a dash controlled factory lockup in 2nd, 3rd and OD all you need to do is have power running to the purple wire (A PIN) and a switch that goes between the tan wire and it's grounding point.

My confusion was I always thought the "toggle switch" was to control the power to the transmission when in fact it is either making or breaking the ground.

Pretty simple stuff, it just took awhile to realize it! :)

Posted this info for others who may be having the same problem.

Apparently the easiest way to get the info you are looking for is to identify which plug your transmission has. Mine is a 3 wire plug with purple, tan and blue. In this case the blue remains unused.

You can access the SAME wire/circuit at the ALDL (diagnostic port under the dash). To gain full TCC control (in 2,3,4), you'll have to bypass the gear range grounding switches in the tranny, accessible once the pan is removed. The later the model year, the more switches.

Engine and tranny are in a 1954 GMC Military 6x6. No diagnostics port but I do have a nato slave connector. LOL! :D

If I hook it up the way I described above, with the 12+ to the purple and a switched ground to the tan wire will it function properly?

I'm in no rush to get this done. Truck is still a work in progress but is under $1000 from being finished now.