Tranny Wiring problems?

okay I finally got around to swapping the drivetrains in my jeeps.

an 88 commanche got the engine/tranny/Tcase from an 89 cherokee. Everything worked fine in the cherokee before I swapped it out.
I got it running and now it does EXACTLY the same thing it did before the swap. Namely: when you put the gear selector in D it does nothing but rev, but when I put it in L I get good engagement of 1st gear. I can then shift it through the gears manually.
I don't believe the converter is locking...does that make any sense? And could that be a wiring issue somewhere in the harness?

need some thoughts before I loose my mind!

Check that the Transmission Computer Unit (TCU) has power on the yellow and red wires. The yellow wire has a fuse inline up near the TCU, which btw it located under the lower edge of the dash on the passenger side. If the TCU has no power, you'll get 4th in (D), 3rd in (3), and 1st in (1-2). It's actually the first test in the FSM to rule out mechanical problems.

I'm assuming you plugged in the cable from the tranny?