If you do not have power on the light blue /black wire than you need to check it at the fuse box. The wire is powered off the accessories relay.If you do not have power coming off the fuse box than check the accessories relay for power if it has power than the fuse box is bad.
If you have all that than check for power to the acc relay from the battery saving relay and if you have power than yes the GEM is bad and not grounding the circuit.I personally would just go to a salvage yard and get one for a 2000 with a ll the same options as yours. If you purchase new you will need to have it programmed to your car the scanner would need to be able to reprogram the module most none dealer scanners will not do that function. A third option is to install a inline fuse holder and install a 30 amp circuit breaker in the holder and wire it to the light blue/black wire from a feed off the ignition switch that is only hot when the key is in run or acc. I like to try and give several options when there is one available. You would lose the feature of being able to roll up the window with the key.
So I will need to replace the fuse box?