Serial Data Power Mode
On vehicles that have several control modules connected by serial data circuits, one module is Power Mode Master (PMM). On Aztek, PMM is Body Control Module (BCM). The PMM receives 3 signals/circuits from ignition switch. These are Unlock (IGN0), Run/Crank (IGN1) and Accessory (ACC) ignition switch signals/circuits. To determine correct power mode 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 engine run flag. Chart below indicates the mode detected and transmitted by PMM. See Fig 1.