Secondary air monitor will not run. 2001 Chevy Silverado 5.3L

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. What would be my next option? What sensors would cause the Secondsry air monitor not to run? Any help is appreciate.

Answer:		How to Perform a Chevy Silverado Drive Cycle The Chevy Silverado drive cycle below will "complete" or make "ready" your truck's emission monitors, including the EVAP monitor, Oxygen Sensor monitor, EGR monitor, and Secondary Air Injection. Be sure to obey all traffic laws while performing drive cycles. Perform the Chevy Silverado drive cycle at your own risk. In regards to the specific matter at hand, having driven your Chevy Silverado for 1000+ miles without accurately following the GM Drive Cycle will not guarantee that your truck will complete the drive cycle. If after completing the drive cycle your truck will still not complete the Secondary Air Injection monitor we have to recommend visiting the dealership or the smog check referee's office. We have not been able to find any TSB concerning this issue but if the smog check referee's office is unable to find/diagnose the fault which is causing the air injection monitor to not set they may issue you a one time smog check waiver; allowing you time to research this fault further. Start Here: COLD START: Begin from Cold Start, and ignition in OFF position for at least 1 hour. Insure your Chevy Silverado's fuel tank is between 1/4 and 3/4 full. Engine coolant temperature must be below 122°F and within 11°F of the ambient air temperature. Do not leave the key on prior to the cold start or the heated oxygen sensor (O2) diagnostic may not run.  IDLE TIME: Run engine (do not drive) for 2 1/2 minutes with the air conditioner on and rear defroster on. During this period the ECU will be running the Oxygen Sensor Heater self-test, Air Injection System Passive Air test, EVAP Purge "No Flow" test, Misfire Detection.  ACCELERATE: Turn off the air conditioner and rear defroster and begin driving your Silverado. As soon as possible apply half throttle until 55mph is reached. The ECU will now run self-tests on the Misfire Detection, Fuel Trim, and EVAP Purge Flow.  HOLD STEADY: Hold your speed steady at 55mph for three minutes. During this time the Oxygen Sensor O2 response, Air Intrusive (AIS System), EGR Flow, Purge Valve, Misfire Detection, and Fuel Trim diagnostics will be performed.  DECELERATE: During this step slowly let off the accelerator pedal. Do not brake or shift in order to slow down. It is important to let your Silverado coast along gradually slowing down to 20 mph. The ECU will once again self-test the EGR System, EVAP Purge System and Long Term Fuel Trims.  ACCELERATE: Go ahead and accelerate again at 3/4 throttle until 55-60mph is reached. This will perform the same self tests as during the first acceleration step.  HOLD STEADY: Hold steady speed once again. This time at 55mph for five minutes. During this time, in addition to running the self-tests as during the first HOLD STEADY step, the ECU will perform the catalyst monitor diagnostics. If the catalyst (Catalytic Converter) is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst,or in order to Complete the CAT Monitor.  DECELERATE: This will perform the same diagnostics as in the first Deceleration. Remember not to press the brakes or shift gears (don't press the clutch if equipped). This ends the drive cycle. Performing the drive cycle on your Chevy Silverado at least twice will ensure all monitors run, including the EVAP monitor, and your Chevy Silverado is ready for the smog check. Should you want to perform specific Monitor self-tests follow the steps below. Catalyst Monitor (CAT):  Prerequisite: No trouble codes present, Intake Air Temperature (IAT) above 32 Degrees (F), Engine Coolant Temperature (ECT) is above 167 Degrees (F); Mass Air Flow sensor is indicating greater than 15 gm/s, engine load is below 63% and steady, engine speed is below 3000 RPM.  1. Idle vehicle 5 minutes (achieve closed loop)  2. Drive 5 min at steady speed above 55 mph  3. Drive 2 min at steady 40 mph  4. Drive 2 min at steady 55 mph  EGR Monitor (EGR):  Prerequisite: No trouble codes present, Engine Coolant Temperature (ECT) is above 75 Degrees (F); barometric pressure (BARO) above 72kPa. 1. Idle vehicle 5 minutes (achieve closed loop)  2. Accelerate and drive for 1 min at steady speed above 50 mph  3. Slow vehicle down to 20 mph. Do not use brake clutch, or shift gears.  4. Repeat steps two and three 5 times.  GM and Chevy run their EGR monitor during the deceleration portion of the drive cycle.   Evaporative Monitor (EVAP):  Prerequisite: No trouble codes present, Fuel tank between 1/4 and 3/4 full. 1. Drive 5 min at steady speed between 30 and 60 mph  2. Stop vehicle and idle engine for 4 minutes. 3. Turn engine off. Remove ignition key. The ECU will run the EVAP Monitor once the engine has been shut down and ignition turned off. O2 Sensor Monitor (O2):  Prerequisite: No trouble codes present, Intake Air Temperature (IAT) above 32 Degrees (F); Engine Control Temperature (ECT) is above 167 Degrees (F) 1. Idle vehicle 4 minutes (achieve closed loop)  2. Drive 3 min at steady speed above 50 mph  3. Drive 2 min at steady 40 mph  4. Drive 2 min at steady 50 mph posted by SmogTips Support