Circuit/System Description

This system uses a dual battery configuration which includes the 12 V primary battery and 12 V auxiliary battery. The dual battery control module switches the 12 V primary battery and 12 V auxiliary battery in and out at appropriate times to support vehicle loads and battery charging. During engine crank, the auxiliary battery is switched in to supply voltage to the vehicle loads (except the starter motor which receives voltage from the primary battery), and the ECM monitors the auxiliary battery voltage through the IGN input.