The little Arduino isn't bricked but doesn't want to play for some reason so it's been shelved for more investigation another day. My other Arduino does exactly what I wanted to achieve regarding the signal conversion so I'm now waiting on 2 others on small pcbs that are programmed via the USB port rather than the UART on the little one, with the idea of providing you with one if you want it.
I sent you a PM with more details. Please let me know if you can't access it as I could use email.
For anyone interested, a big thanks to Graeme. Graeme has built an Arduino module that receives a voltage regulated signal from a GM auto shifter and split that into 2 channels as outputs that are wired into the Holley Terminator X Max with 6L80 controller. The Holley ECU then sends a canbus signal to the 6L80 TCM to command an up or down shift. It works on the bench and next step is to test it wired to the Holley and Holley to the 6L80. With fingers crossed, i should see the shift command in HP Tuners which will be reading the TCM. Will be a month or so before i get to the final stage of testing with the engine install next on the list, then wiring. much appreciation. Mark