Remote Control Door Lock Receiver (RCDLR)
WARNING: This page is about a different car, the 2010 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
The RCDLR is a multi-function module which controls all the vehicles antennas for passive keyless entry functions. The RCDLR also acts as the receiver for active keyless entry and tire pressure monitoring (TPM) functions, as well as controlling all immobilizer functions.
The RCDLR's RF antenna is located in the back glass, and there is a coax cable connecting the glass antenna to the module located in the trunk.