Theory Of Operation

GENERAL OPERATION:  The Engine Stop/Start (ESS) system uses an In-Rush Current Relay (ICR) to reduce the voltage drop during an AutoStart event in order to maintain uninterrupted functionality of the consumer electronics and vehicle subsystems during engine cranking. The In-Rush Current Relay is connected in series with the main battery feed to the Starter Motor. The In-Rush Current Relay is normally closed  when de-energized allowing full battery voltage to the Starter Motor. When 12 volts is supplied to the In-Rush Current Relay coil from the ICR Control Relay, it energizes (opens)  diverting the battery voltage through the internal resistor.

• During a manual ignition crank event  when the relay is de-energized (closed) full battery current is allowed to pass through the In-Rush Current Relay, directly to the Starter Motor bypassing the resistor. When the In-Rush Current Relay is in this mode of operation, the voltage drop is approximately 3.5 volts during cranking.
• During an ESS AutoStart crank event  the In-Rush Current Relay is energized via the ICR Control Relay which opens the In-Rush Current Relay. When open, battery current to the Starter Motor is diverted through the resistor inside the In-Rush Current Relay to the Starter Motor. Once the Starter Motor has engaged the In-Rush Current Relay is turned off allowing full battery current to flow to the Starter Motor. This reduces the voltage drop during an AutoStart cranking event to approximately 2.0 volts.