error code 42 on 92 buick riviera

i have 92 riv. and cant seem to get it started. battery died so i replaced it and only turns over but no start.when i run for codes i get code 42, also while im connected for the codes my fan, a/c, fuel pump etc all go on and my ECM is clicking ,sounds like a hard drive searching, but nothing gets it started. ive seen many things in the forum ignition module, ignition connectors etc just trying to find some solution.i mean for the code 42 they suggest open line in bypass or EST line or bad ground but i do not know where these are and cant seem to find way to locate. if anyone has any ideas on how to solve this problem or if it is my ECM or just a open line please let me know and if you can tell me how to find these lines would be great.

Normally 42 will not prevent the car from starting, check for spark and fuel pressure, scan it and see if you get cranking rpms and post back.