Circuit/System Description

The 12 volt start/stop system is used to reduced fuel consumption and emissions by automatically turning off the engine when coming to a stop and restarting when moving again. When coming to a stop, assuming no disable conditions exist, the engine will automatically turn off at 5 km/h. The engine will automatically restart when the driver presses the clutch pedal (manual transmission) or when the driver releases the brake pedal (automatic transmission).

The 12 volt start/stop system can be enabled or disabled by the driver using the ECO switch. The body control module applies voltage to the switch signal and monitors the voltage. When the ECO switch is pressed, the signal circuit is pulled to ground and voltage at the body control module is low, indicating the switch has been pressed. The body control module also controls the ECO switch indicator. When the 12 volt start/stop system is enabled by the driver, the body control module will illuminate the indicator by providing voltage to the indicator control circuit.

To eliminate unwanted infotainment system effects during engine cranking, the 12 volt start/stop system utilizes a power supply transformer that provides a steady B+ to the infotainment system though the battery saver relay. During engine cranking, system voltage may momentarily drop below 10 volts. This momentary drop in voltage may cause the vehicle infotainment to turn off and restart during a start/stop event. The power supply transformer maintains steady B+ to the infotainment system to prevent an infotainment restart during cranking.