02 Suburban Security light

The damn thing keeps coming on. I've been into this vehicle twice since the installation, each time I check the passlock system ( which seems to change by a LOT every time I check it) . I average out about five readings from the factory passlock wires and set my bypass to match this averaged value. It will work fine. Then a couple weeks later, the customer calls and says the light is back on. So I go through this whole thing again. Then it's fine for a couple more weeks. The bypass unit is rock solid where I told it to be, but the factory system has drifted away again! Anybody ever had this problem? I'm running out of things to try, and the customer is running out of patience.

How are you testing for the correct resistance? it would help to know because I haven't seen one that "changes". let me know

I strip back the black (passlock ground) and measure between that and the key side of the yellow passlock wire. Then I switch my leads around and measure again.