Truck won't read key only key I have no door pad. How do I get truck to read key or temp. Bypass

no bypass for the PATS system. its possible that the module/antenna on the column went bad.with the key in the RUN position,is the theft light blinking 3 time per second? and do you have 2 keys? why was the PCM changed out? you can't just put another PCM in it without having the following done>>>Passive Anti Theft System (PATS) Module Requires Programming After ECM Install... Units Must Be Flashed On The Vehicle... Vehicle Specific On-Car Programming Must Be Performed After Installation To Prevent Driveability Issues... Parameter Reset May Be Required After Installation If Modified Vehicle. it really thinks it's been stolen now,and went into LOCK-DOWN MODE!!