2004 deville won't start
 

Have a 2004 Deville that will not turn over. During a recent road trip I stopped to get food and when I went out to turn the car back on it would do nothing. Had it towed, and tow driver seemed to believe it was the starter. Just got done replacing the starter, and that was not the problem. Seems to be getting power to the starter. Windows and locks do not work, and some of the dash display does not come on. It has a fully charged battery. Could this be a bad ignition switch, or is there something I am missing. Any help is greatly appreciated.

Check condition of battery cable, positive battery posts used to leak corroding copper cable. Check voltage at fuse box noting what has voltage and if is 12v or something else. then re-post

2004 deville won't start
 

I have 12.3 volts on the cable to the starter. When I turn the key to the run position,the locks,windows and radio doesn't work but when I turn the key to off, remove the key and open and shut the driver door they all work. Was able to get a IPC U1301 code.

You need to check voltage to fuses in fuse box under seat. U1301 high voltage on data circuit. Mods? Ground wire connection?

2004 deville won't start
 

Thanks slowroll.
Turned out to be the ground wire from the fender to the alternator bracket. Replaced and it started right up.