I turned the ignition and only heard to "clicks" then total power outage?

A sudden and complete power loss in your 1999 Chevrolet Silverado can be caused by several factors. Here are some possible reasons for the issue:

Dead Battery: The most common cause of sudden power loss is a dead or severely discharged battery. It could be due to an aging battery, a loose or corroded battery terminal, or leaving an electrical accessory on overnight.

Faulty Ignition Switch: The ignition switch could be faulty, preventing the electrical system from receiving power when you turn the key.

Bad Starter: A failed starter motor can cause a click noise when you try to start the engine, followed by a complete loss of power.

Blown Fuse: A blown fuse in the main electrical system can lead to a sudden power outage.

Faulty Alternator: If the alternator fails, the battery will not receive a charge while the engine is running, leading to a discharged battery and power loss.

Faulty Battery Cables: Loose or corroded battery cables can hinder the flow of power from the battery to the rest of the electrical system.

Here are some steps you can take to troubleshoot the issue:

Check Battery Connections: Inspect the battery terminals for any corrosion or looseness. Clean the terminals if necessary and ensure they are firmly connected.

Test the Battery: If possible, test the battery voltage using a multimeter. A healthy battery should have around 12.6 volts. If the voltage is significantly lower, the battery may need recharging or replacement.

Check Fuses: Inspect the main fuse box for any blown fuses and replace them if needed.

Verify Ignition Switch: Check if the ignition switch is functioning correctly. Listen for any clicking sounds from the switch when you turn the key.

Consider the Starter: If everything else checks out, the starter might be faulty and in need of replacement.

Verify Alternator Function: Once the battery is charged or replaced, check if the alternator is charging the battery correctly.