Serial Data Power Mode

WARNING: This page is about a different car, the 2005 Pontiac Aztek and 2005 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle the PMM is the body control module (BCM). The PMM receives 3 signals/circuits from the ignition switch. These are the Unlock (IGN 0), Run/Crank (IGN 1) and Accessory (ACC) ignition switch signals/circuits.

To determine the correct power mode the PMM uses:

The state of these signals/circuits, either switch closed (B+ = 1) or switch open (open = 0)
The sequence of switch closures received by the PMM
The status of the engine run flag

The chart below indicates the modes detected and transmitted by the PMM:

Power Mode Description and Operation

-	-	Sampled Ignition Signal State			Look Up Table Contents		-
Power Mode Selected/Expected	Engine Run Flag Serial Data	Accessory	Run/Crank (IGN1)	Unlock (IGN0)	DTC Set	Power Mode State	Key-In Sense
OFF	0	0	0	0	0	OFF-AWAKE	NA
OFF	1	0	0	0	0	OFF-AWAKE	NA
RAP	1	0	0	1 to 0	0	RAP	NA
RAP	0	0	0	1 to 0	0	RAP	NA
RAP-UNLOCK	0	1 to 0	0	1	0	RAP-UNLOCK	NA
RAP-UNLOCK	1	0	0	1	0	RAP-UNLOCK	NA
UNLOCK	0	0	0	0 to 1	0	UNLOCK	NA
UNLOCK	1	0	0	1	0	UNLOCK	NA
ACCESSORY	0	1	0	1	0	ACCESSORY	NA
RUN	1	1	1	1	0	RUN	NA
RUN	0	1	1	1	0	RUN	NA
CRANK	0	0	1	1	0	CRANK	NA
OFF	0	0	1	0	1	OFF-AWAKE	Key Not In
RAP	0	0	1	0	1	RAP	Key In
ACCESSORY	0	1	0	0	1	ACCESSORY	Key In
RUN	0	1	1	0	1	RUN	Key In
RUN	1	0	1	0	1	RUN	Key In
RUN	1	0	1	1	1 ¹	RUN	Key In
RUN	1	1	0	0	1	RUN	Key In
RUN	1	1	0	1	1	RUN	Key In
RUN	1	1	1	0	1	RUN	Key In
Bold text indicates a DTC setting situation. ¹ DTC sets after one minute in this situation.