Here's what I did. I was in the same situation as you, both check valves replaced, I could hear the pump come on at start up, did the drive cycle numerous times over 3 weeks. I knew everything was working as it should I had a scanner and could see the o2's go lean when the pump was commanded on, I could see the fuel trim go up when the pump was commanded on. I drove 500 to 600 miles trying to get it to complete but it never did. One night I drove for 20 mins at 55 and still nothing. I got off the freeway and cleared the codes while I was driving, got back on the freeway and drove 55mph real easy with very little load on the engine and within 1 min the secondary air monitor was complete. So the next morning I did the drive cycle from cold start to get the o2 heater monitor , and the catalytic monitor to complete and I was done. I think what happened in my case and a lot of others is the computer does a passive test at first start up when its cold, if it passes that test it doesn't run the test again during that ignition cycle so it never completes because I don't think the passive test completes the monitor it only checks for problems in the system. So by clearing the codes while I drove it also cleared everything else in the computer memory and it didn't see a passive test so it ran the active test which is whats needed to complete the monitor. At least that's the only thing I can think of . Let me know if it works for anyone else
