For 1990-2009 cars

### Electrical Power Management

The electrical power management (EPM) is used to monitor and control the charging system and alert the driver of possible problems within the charging system. The EPM system makes the most efficient use of the generator output, improves the battery state-of-charge (SOC), extends battery life, and manages system electrical loads.

The load shed operation is a means of reducing electrical loads during a low voltage or low battery SOC condition.

The idle boost operation is a means of improving generator performance during a low voltage or low battery SOC condition.

Each EPM function, either idle boost or load-shed, is discrete. No 2 functions are active at the same time. Idle boost is activated in incremental steps, idle boost 1 must be active before idle boost 2 can be active. The criteria used by the body control module (BCM) to regulate EPM are outlined below:

Function | Battery Temperature Calculation | Battery Voltage Calculation | Amp-hour Calculation | Action Taken
--- | --- | --- | --- | ---
Idle Boost 1 Start | Less Than -15°C (+5°F) | Less Than 13 V | -- | First level idle boost requested
Idle Boost 1 Start | -- | -- | Battery has a net loss greater than 0.6 AH | First level idle boost requested
Idle Boost 1 Start | -- | Less Than 10.9 V | -- | First level idle boost requested
Idle Boost 1 End | Greater Than -15°C (+5°F) | Greater Than 12 V | Battery has a net loss less than 0.2 AH | First level idle boost request cancelled
Load Shed 1 Start | -- | -- | Battery has a net loss of 4 AH | Rear defrost, heated mirrors, heated seats cycled OFF for 20% of their cycle
Load Shed 1 Start | -- | Less Than 10.9 V | -- | Rear defrost, heated mirrors, heated seats cycled OFF for 20% of their cycle
Load Shed 1 End | -- | Greater Than 12 V | Battery has a net loss of less than 2 AH | Clear Load Shed 1
Idle Boost 2 Start | -- | -- | Battery has a net loss greater than 1.6 AH | Second level idle boost requested
Idle Boost 2 Start | -- | Less Than 10.9 V | -- | Second level idle boost requested
Idle Boost 2 End | -- | Greater Than 12 V | Battery has a net loss less than 0.8 AH | Second level idle boost request cancelled
Idle Boost 3 Start | -- | -- | Battery has a net loss of 10 AH | Third level idle boost requested
Idle Boost 3 Start | -- | Less Than 10.9 V | -- | Third level idle boost requested
Idle Boost 3 End | -- | Greater Than 12 V | Battery has a net loss of less than 6 AH | Third level idle boost request cancelled
Load Shed 2 Start | -- | Less Than 10.9 V | Battery has a net loss greater than 12 AH | Rear defrost, heated mirrors, heated seats cycled OFF for 50% of their cycle. The BATTERY SAVER ACTIVE message will be displayed on the DIC.
Load Shed 2 Start | -- | Less Than 10.9 V | -- | Rear defrost, heated mirrors, heated seats cycled OFF for 50% of their cycle. The BATTERY SAVER ACTIVE message will be displayed on the DIC.
Load Shed 2 End | -- | Greater Than 12.6 V | Battery has a net loss of less than 10.5 AH | Clear Load Shed 2
Load Shed 3 Start | -- | Less Than 11.9 V | Battery has a net loss greater than 20 AH | Rear defrost, heated mirrors, heated seats cycled OFF for 100% of their cycle. The BATTERY SAVER ACTIVE message will be displayed on the DIC.
Load Shed 3 End | -- | Greater Than 12.6 V | Battery has a net loss of less than 15 AH | Clear Load Shed 3