dbw help 2002 LQ9 DTC P1518

[ragtp66]

I have a complete swap from a 2002 Escalade EXT I owned and drove the truck for over two years prior to the swap. I took the Engine, 411 PCM, TAC module, APP (gas pedal) and the harness from TAC module to the APP. Followed Brendan's harness cleanup from LT1swap dot com. With my TAC module connected it takes the PCM down I get no communication with scan tool and the fuel pump relay signal wire has constant but pulsing voltage on it. I have checked all my pinouts are correct clean and not backed out. I have checked continuity as well as voltage drop not seeing more than 100mv drop on any circuit. 5volt refs check out good. I have tried disconnected TAC motor connector, tps, APP pedal which should only leave power, ground and serial data lines and it still instantly takes the pcm down. if I disconnect the TAC module 16 wire connector the pcm communicates as it should and the fuel pump relay comes on for 2 seconds for priming and then off as it should. I have tried swapping TAC modules I have 2 others from an 01 truck as well as the two APP -gas pedals no change.
My tuner uses HPT and turned off vats, removed egr, evap, ac, and automatic trans as I am using a t56.
Grounds are all clean to bare metal clean and tight. I have additional ground straps from block to frame and from firewall to block.
All new american auto wiring harness and dakota digitals if that matters.
I do not have any of the cruise control wires or the CHMSL supply voltage on the 16 pin TAC connector hooked up. I did not think I needed this since I am not running an automatic I thought I could wire it later when I add cruise control. APP and TPS sensors sweep as they should in opposite directions using an analog meter. The throttle body blade has the same pulsing as the fuel pump control wire if touch a finger to it while observing the test light on the FP relay I can feel in my fingers what I am seeing on the test light.

Any help would be greatly appreciated.