CTS V8-5.7L VIN P (2004)
Clock: Description and Operation
CLOCK
The radio sends current time to the IPC via class 2. The IPC receives a class 2 message from the radio indicating the time. The IPC analog clock, if
equipped, zeroes itself to 12:00 during key up and then resets to the current time via the class 2 message received from the radio.