trappercrk

Got a pullout from a 2014 2500hd. 6.0L, 6L90e & elec tc. Installed into my 1998 K2500. New engine came with ecm & harness for eng / tranny / tc. Purchased correct 2014 underhood fuse panel, bcm, underdash fuse panel, instrument panel, harnesses, column controls, etc. Can start engine and shifts great. Problem is instrument panel gauges and PRND indicator don't work. Instrument panel does light-up and display errors (like no airbag & ABS - expected since don't exist). Also the reverse lights always 'on' when ket turned (with key turned, the bcm is sending signal to reverse light relay on underhood fuse panel). Thinking low spd GMLAN signal not getting to bcm or bcm not programmed? Been losing hair trying to solve issue for last 4 months. Guy on gm-trucks recommended this site.