I'm getting back to working on this after a long hiatus - winter's here.
I've checked/done pretty much everything listed in this thread. Some of them multiple times. Recently went back to the very basics: made sure Remote Start is turned on in DIC - check. Made sure I have AP3 RPO - check. No CEL. No funky electrical gremlins of any kind. The only codes I get from all Tech 2 diagnostics: 1) lost connection with radio (aftermarket) and 2) B2555, which is covered from this TSB:
https://static.nhtsa.gov/odi/tsbs/2013/SB-10051905-4497.pdf
The main things I know:
1. Both remotes will initiate the sequence. Parking lights flash, fuel pump primes for a second, a relay clicks under the hood.
2. Tech2 tells me there is an "ECM Crank Abort" on the remote start screen. I have had zero luck in finding any cause of that abort.
I have not found a way to actually use the Tech 2 to perform the remote start. It allows me to test all the buttons on the remotes, and all buttons including RS register a push. So I'm convinced it's not the remotes. Tech2 has also allowed me to rule out door locks, rear lift gate and hatch, and hood ajar. Everything is testing properly.
What could cause the ECM crank abort method without a CEL or other codes?
@swathdiver (or anyone else) does the AllDataDIY have a diagnostic procedure? I wouldn't mind paying for the short subscription if there is one available. I did purchase the $10 ebay service module that comes in like 30 different files. It's a good copy and will be useful eventually, but I can't find a single thing about remote start in there. There doesn't seem to be a master index that covers all the different files. (or really any index at all)