Serial Data Power Mode

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 BCM. The PMM receives 3 discreet ignition switch signals to differentiate which power mode will be sent over the Class 2 Serial Data circuit.

To determine the correct power mode the PMM uses the following circuits:

• Ignition 0
• Ignition 1 voltage
• Ignition 3 voltage