I have a 2000 Tahoe i don’t have any power to rear
windows checked all fuses and relays replaced
both regulators both switches
Did you check voltage and ground, anywhere? Use a test light. In the diagram, I count 4 fuses and two circuit breakers, check for voltage. The circuit breakers are for left and right, both front and rear on one side. Maybe a wiring circuit problem and not a component?