Thanks for the update. Nice to know you got it under control.
I'm a new TT owner and hope others with more experience will chime in with answers to your question: Why didn't things work when plugged into the truck?
My guess is that because the trailer battery was stone cold dead, the truck connector couldn't supply enough power to run the slide motor. That is just my guess.
Sherm & Terry w/rescue Eydie (min Schnauzer) & Charley (std Poodle)
2015 Jay Flight 27RLS, GY Endurance (E), Days: 102 '15, 90 '16, 80 '17, 161 '18
2006 Ford F350 PSD, 4WD, CC, LB, SRW, Cmpr. pkg, Equal-i-zer 4-p, Continental ContiTrac TR