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Guys, I need some help with my 2001 5.3l Silverado. I need to smog test my truck but in Caliornia all monitors must be ready to pass. The only monitor that has not completed is the secondary air injection. The truck is not throwing any codes and there are no drivability issues. I've complete every drive cycle I can find numerous times, including the generic GM drive cycle, none have enabled the secondary air injection monitor. I've driven the truck for at least 2 months and put on 1000+ miles since changing the battery which caused my monitors to reset. Each morning I complete a cold start idle for 2.5 minutes hoping the secondary air will run. Below is a list of items I've inspected or changed in an effort to fix my problem. Secondary air pump-I tested its operation at startup. The pump enables at startup and pumps air at an acceptable volume. There are no signs of wear or issues with the pump. Secondary air valve- I tested operation at startup The valve opens and allows air to flow from the pump to the exhaust. There are no signs of wear and all vacuum line were inspected for leaks. Secondary air check valves- Both valves were inspected and replaced due to carbon buildup. Neither were clogged but I still replaced. O2 sensors- I replaced both pre cat O2 sensors because both had 100,000+ miles. The O2 sensors have been monitored using a scan tool and no signs of issue have been noted. I've monitored both pre cat O2 sensors during startup and I can see when the secondary air pump is enabled. Both sensors go lean until the pump is deactivated and closed loop is achieved. I've monitored engine coolant temp, intake air temp and ambient air temp with my scan tool to ensure all sensors are allowing for a cold start. Again the truck runs great and has no pending or stored codes. It just will not run the secondary air injection test. I'm no slouch when it comes to wrenching on cars but this one has me stumped! What would be my next option? Does anyone know what sensors are monitored to enable the secondary air injection monitor? Thanks for the Help.