Voltage Backfeed w/ Window Roll Up Module

I am using two generic (cheap from Ebay) window rollup modules. One module rolls up two windows, the other module closes the sunroof. Problem: The window roll up modules are activated by applying ground to a brown wire on each module. This works well. I have had them hooked and working for over a year now. I have been feeding them the negative ground from the starter kill (negative) output of my Crimestopper keyless entry system. I have been experiencing battery drain when the weather gets colder. Once I got into it, I have discovered that the BROWN wires from the Window Roll Up Modules are metering +12 volts at rest when no ground is applied. So when the system is activated and the starter kill output is active and once the windows roll up the the starter kill circuit is receiving a +12 voltage backfeed. Is this what is causing battery drain? Why doesn't it a blow a fuse or something since voltage seems to be connected to ground. Last note, when I use my meter to verify that the Crimestopper is putting out a negative output I get about 1-2 volts positive. Is this normal? I check this by hooking one lead of my meter to ground and then the other to the grounded output and put the meter on CONTINUITY? will this give me an accurate reading? Or should put the Positive leader of the meter on a positive source and the negative on the Grounded starter kill output? Thanks for any help that anyone can provide. werd

Another thought... would a diode stop the window roll up module from backfeeding voltage when ground is not being applied?werd