how does the ECM control lockup?

[frotosride]

I have done extensive research on making my own lockup controler if need be however, The 700r4 and ecm cam in the truck and are all oe. What I would like it to make a way to tcc lockup when I want it. The main reason I want this is because I have noticed that at any speed over 55mph I cannot achieve lockup. From what I read the ECM maily switches the ground on/off inorder to achieve lockup. My question is, if all the ECM does is switch the ground how does it monitor the parameters and is there a constant +12v supply to the tranny? If anyone has an OE wiring diagram I would greatly apprecitive. I want to also know what each of these wires control and what pin they are associated with...Light blue, pink, tan...A,B,D pin?

If there is no safe way to maintain the ecm control and make a manual override then I will just use a vaccum switch and 5=pin relay to acchieve what i want with a manual override switch.
Thanks in advance for any help.

[VileZambonie]

Did you search this on here? There's been several posts on this.

http://forum.73-87chevytrucks.com/smforum/index.php/topic,7310.msg42965.html#msg42965

[DrDaryl]

Hey Vile, the "4th gear switch" on the diagram you referenced--where does it screw in?
thanks

[Captkaos]

It goes in the transmission.

[frotosride]

I have searched through countless post on this sight and I haven't found the answers yet. This is why I decided to post a new thread.

[VileZambonie]

Sorry, been extremely busy and getting ready to leave for a trip. Unless someone else has time right now, search "lock up" "tcc" "converter clutch" etc

[Captkaos]

There are links in the post Vile put up that show you how to hook one up manually.

[frotosride]

Thanks, Vile and Capt, I prety much got the manual hook up part down and it looks like thats the way I'm going to got after I try just adding a switch to the ground and pray it doesn't mess up my ecm...If  so then I will have to do the manual hook up. Good luck on the trip. I 'm being relocated to Norfolk, Va and thats why i want to figure this out. However, I now have a new issue I have to deal with....seems that I gave a little too much loud pedal and completly smashed the drivers door and all but decentigrated the window. Thanks to a good friend who has more than ample parts of our favorite year model chevy trucks I picked up a door for $50 and now its prep and paint time.