I reopen this old thread simply to give relevant information. I did some searches last month and could not find anything useful. So I will leave the information here for future reference.
The Utility Light switch receive +12V from a white wire. Actually on my switch it is the first white wire of the switch in the middle of three wires. Test it with a voltmeter.
This white wire goes directly into the BCC Battery Control Center on the connector P6. So this wire is not part of a harness but is alone. The J6 connector is just below the Luggage Lt fuse F14. So if you see the fuse, the connector is under it at 1/4 inch with a white wire on it. If you have no power to the switch and the fuse is good, then simply change of fix this wire.
On this picture you see on top left corner a pink fuse which is F14. The connector P6 is just below.