dtc code 0449. replaced vent valve, repaired bad pins in pass through connector on 2005 Chevrolet Uplander

Checked the wiring at passthrough when replacing pins.. wiring good through vent valve, back to connector.. QUESTION.. with KEY ON, should I see B+ on the red/white wire? I checked it and I don't have any voltage.. when is voltage applied, at key on or at a computer detrmined time?
I know the system supplies B+ to the vent valve, and through ground, back to the ecm.. but when should I see B+? Thanks.

Asked by for the 2005 Chevrolet Uplander