Before I try to start it. It’s loc mode. I found out 3yrs. Had to put in a fuel pump. Stereo locked up. Got a Haynes book on the truck. Anytime the battery is disconnected you have to disable stereo. Didn’t come with book or code for stereo. I have to re-key the truck. Should I try to start it without resetting the anti-theft stereo?
If I'm not mistaken, your 2000 Silverado uses Passlock antitheft to immobilize the engine. Your factory radio may have a separate antitheft program completely separate from the vehicle antitheft system. When new, owners have the option to program a personal pin code into the radio or leave it 'unlocked'. Unlocked should display '0000' and if seen then simply turn on the radio to leave it in unlocked mode. The buttons on the radio select position and increasing numbers to program a personal pin. Once programmed, the radio memorizes the pin and the next time battery power is removed the radio enters locked mode. Restoring battery power will show the display and may ask for pin before unlocking it. The radio message appears only when the vehicle battery is disconnected/reconnected.
The pcm shares a fuel password between itself and the body control module and a Passlock sensor in the steering wheel (detecting lock cylinder rotation when the ignition key is turned) that makes up the factory Passlock antitheft system. Passlock is enabled/disabled with factory remotes. Whether the pcm or bcm is replaced, either a dealer ten minute or diy thirty minute marrying routine is performed before both can communicate to each other otherwise the security password exchange is false and triggers Passlock security to disable injector operation with the security indicator flashing quickly. The radio antitheft program has no effect on the vehicle antitheft system. Passlock has no effect on the radio antitheft program.
You're describing two separate issues.