2000 Chevy Tahoe No power

Check power at the ignition switch. If you have power into ignition switch then replace it because you are not getting power out of it. You can access the fat red wires at the base of the steering column. Make sure they have power

Any lights? Horn? radio? If not, Check power circuits...
Power Circuits 1. Using a voltmeter, check for battery voltage between PCM continuous power terminal(s) and ground. See CONTROL MODULE CONNECTOR TERMINAL IDENTIFICATION . See Fig. 1 - Fig. 4 . If battery voltage is not present, check for open fuse or fusible link. If okay, check for open in wire between PCM terminal and power source. 2. Turn ignition switch to RUN position. Using a voltmeter, check for battery voltage between PCM ignition power terminals and ground. If battery voltage is not present, check IGN fuse. If fuse is okay, check for an open in wire between battery and ignition switch, and between ignition switch and PCM terminal. If wiring is okay, check for a defective ignition switch. 3. Connect voltmeter between ground and PCM starter (crank) signal terminal. On vehicles with manual transmission/transaxle, depress clutch pedal. On vehicles with automatic transmission/transaxle, position gear shift lever in Park. On all vehicles, turn ignition switch to START position. Battery voltage should be present ONLY when ignition switch is in START position. 4. If voltage is not present, check CRANK fuse or fusible link between ignition switch and PCM terminal. If fuse or fusible link is okay, check for an open in wire between ignition switch and PCM terminal, or check for a defective ignition switch. © 2007 Mitchell Repair Information