So I put a 700R4 where a 5 speed used to be (bought the car without a motor and trans then swapped in what I had). Both trannys are from an 1987 Iroc. I swapped in the TC brake switch, supplied it with power from the fuse block, then ran a jumper wire over to TC solenoid pigtail. When I swapped in the engine and tranny pair I also brought over the main engine wire harness and computer, so the other two wires from the TC solenoid pigtail are connected into that harness.

But as I drive the car I cannot perceive any torque converter lock up. At highway cruising speed I even tap the brake to unlock the TC to see if the rpm's will bump up and I don't see any change. When driving at 90kph (55mph) the tach reads about 1900rpm or just a touch higher, this is with 3.27 gears and stock tires, does this seem like high rpms to you at this speed? I ran a test light on the brake switch and it works just fine. So I'm wondering if I've overlooked something, or maybe something is wrong inside the trans?

 

1900 at 55 is about right for having OD but not having lockup.

 

So you have a auto memcal in your ECM (computer ) ?

Was the lockup working correctly before the swap?

Have you checked for 12V into ( purple ) and out of ( tan / bk ) wires at the plug on trans?

The tan/bk wire is grounded at the ECM to turn on lockup.Run a temp wire inside the car from that wire to ground through a switch
and see if you can get the lockup to work .Engaging lockup 9 wire to ground ) with car in gear and stationary should make the engine stall.
If it doesn't you know you have internal problems (assuming it passes the above the electrical tests )