Base model 2005 Vibe has power door locks, but no FOB. All door locks and hatch lock open by using key in the driver's door lock or the door lock toggle switch on the driver's door. The locks normally operate fine, but, on several occasions in the car's history, years apart, the locks have stopped working. When this happens, it's all or nothing, as in all door locks and hatch are affected, and they can't be tripped with the key or toggle. Then they will all resume working properly again when I least expect it! They weren't working for over three months most recently, resumed working for a couple of days last week, then back to nothing again. I'm wondering if it's temperature or humidity related? I can't find any information about a power door lock relay, which I thought would be the fix perhaps? I can hear a buzz sound under the steering wheel (near fuse panel) when I toggle the master driver's door lock switch (when the locks aren't working).
Any help to resolve this would be greatly appreciated!