I have a 1998 Mercedes S320 everything is reading ready for smog test except the secondary air system.

1- The air pump works fine I jump started it and it works fine. I also felt it working when I started the car in the morning but once I disconnected the large hose from the air pump it stopped working. I also have a second air pump works the same way no deference.
2- The relay is fine too I replaced it as well. When car is worm and running
I get no readings from the pump connector what so ever but the relay is
fine and I have many other once on the side.
3- All fuses are fine I cheked them one at the time and I have extra once too.
4- I just ran the test again no engine light on but it says P1453 (air injection reaction relay module/air injection reaction pump.
But the relay and pump are good and have extra once What else it could be I wonder any help will be appreciated.