Central Door Unlock

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora and 2001 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

The central door unlock feature is activated when the door key is inserted into, either the driver door lock cylinder, or, the front passenger door lock cylinder, and turned to the Unlock position. The doors will unlock when either of the following happens:

The DDM sees that its door cylinder switch is continuously closed for longer than 3 seconds.
The DDM sees that its door cylinder switch is closed twice in 3 seconds.
The PDM sends a message over the power door serial data line to the DDM indicating that the passenger door cylinder switch is continuously closed for longer than 3 seconds.
The PDM sends a message over the power door serial data line to the DDM indicating that the passenger door cylinder switch has been closed twice in 3 seconds.

The DDM sends a Class 2 message to the RIM indicating the above. The RIM sends a Class 2 message to the DDM to unlock all doors. The DDM sends a power door serial data message to the other door modules to unlock all doors.

The door cylinder switches are a built in part of each doors lock actuator assembly and are wired to either, the driver door module (DDM) or the front passenger door module (PDM). Each door cylinder switch is connected to its exterior door key cylinder by means of a mechanical rod. Each door module supplies battery positive voltage through the door key switch signal circuit, and ground via a ground circuit to the normally open contacts of its respective door cylinder switch. When the switch is closed, voltage flows through the switch, providing the door module with the necessary input.