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 DIM. The PMM receives 4 signals from the ignition switch.

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

• Accessory voltage
• Ignition 3 voltage
• Off/Run/Crank voltage
• Run/Crank voltage

Fig 1: 4-Wire Ignition Switch Table

Courtesy of GENERAL MOTORS CORP.