Circuit/System Description

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The Accessory Power Module (APM) controls the energy flowing between the high voltage, 300-volt, direct current (DC) and low voltage, 14-volt, DC to support the vehicles accessories and charge the 12-volt battery. The APM receives a 14-volt enable command from the Hybrid Powertrain Control Module (HPCM) over the high speed hybrid GMLAN communication circuit. APM functions will run only when the APM Enable is active on the high speed hybrid GMLAN communication circuit.

Heat is generated in the 14 volt APM circuit based on the current demand for the 14 volt systems. The engine control module (ECM) measures the temperature of the power electronics cooling loop and commands the flow of 2 electrical coolant pumps and the radiator fan. The APM transfers heat in the 12 volt circuit to the APM heat plate which is then dissipated at the generator control module coolant radiator.