Sorry if this isn't how to use the forum but I've read 112 pages on the Passlock system and keep ending up in an Impala thred.
My 99 GMC Suburban K2500 7.4 is dead in the driveway.
Started w/ security light coming on while driving. Wouldn't start the other day. Flashing security light. Did the relearn thing, OK for a couple of days. Started flashing, non-start daily. Last time out, got gas and driving home noticed transmission shifting funny. Parked and there it sits. Crank, Starts and Dies... Solid SECURITY light. Researched and found Passlock module going out is a thing. Found a reman online, guy says will cure me. Installed that and no luck...same issue. Thought about the resistor by-pass hack and while in the wiring harness found someone has already done that! Now what? Scans P1629 code. Any help (Besides go the New Rockies route) would be appreciated.