¹ Requires vehicle speed above 8 mph.

This system uses 2 communication lines between the PCM and the generator/voltage regulator. Both of these communication lines use PWM . The generator communication (GENCOM) line communicates the desired setpoint from the PCM to the voltage regulator. The generator monitor (GENMON) line communicates the generator load and error conditions to the PCM. The GENCOM command is only sent by the PCM when it is necessary to adjust the voltage setpoint. If the setpoint does not need to be changed, several seconds may elapse between PCM GENCOM commands. This normal operation appears in the PID as occasional bursts of pulse-width commands. The third pin on the voltage regulator, the "A" circuit pin, is a circuit dedicated to monitor or sense battery voltage.

The PCM simultaneously controls and monitors the output of the generator. When the current consumption is high or the battery is discharged, the PCM raises engine speed as needed to increase generator output. The generator charges the battery and at the same time supplies power for all required electrical loads. The battery is more effectively charged with a higher voltage when the battery is cold and a lower voltage when the battery is warm. The PCM uses a signal from the IAT sensor to adjust the charging voltage according to the battery temperature. The PCM also uses other inputs to control the charging system voltage such as the VSS and engine coolant temperature. The voltage setpoint is calculated by the PCM and communicated to the voltage regulator by the GENCOM circuit based on the needs of the vehicle and the conditions.

The PCM turns off the generator during cranking to reduce the generator load and improve cranking speed. Once the engine starts, the PCM slowly increases generator output to the desired voltage.

The PCM reports any charging system faults and sends a message through the HS-CAN to the BCM . The BCM controls the charging system warning indicator by sending a message over the MS-CAN to the IPC . The IPC then controls charging system warning indication based on the message from the PCM through the BCM . The status of the PCM charging system warning indicator and/or message is confirmed by viewing PCM PID generator fault indicator lamp (GENFIL). Any charging system fault detected by the PCM results in 1 or more DTCs being set and the PID GENFIL having a status of On. If equipped with a charging system warning indicator, the IPC turns the indicator on or off. If equipped with a message center, the IPC displays a CHECK CHARGING SYSTEM message. In some instances, the CHECK CHARGING SYSTEM message may not display if the ignition is ON and the engine is off.

Under certain circumstances, the charging system may have a concern, but still keeps the battery charged and the vehicle running. GENCOM normally initiates charging, but the generator may charge with a fault in this circuit. If the engine operates at more than 2,000 RPM momentarily, the generator may self-excite or start charging on its own. The charging system warning indicator is illuminated and/or CHECK CHARGING SYSTEM message is displayed, and the generator operates in a default mode (approximately 13.5 volts) until the engine is turned off. When the engine is restarted and the engine operates at more than 2,000 RPM momentarily, the generator may again self-excite and again the charging system warning indicator is illuminated and/or CHECK CHARGING SYSTEM message is displayed.

The PIDs and their associated descriptions used in the charging system diagnosis are listed below:

PID	Description	Normal Display	Associated Circuit Name	Connector, Circuit
GENMON	Generator Monitor	Constant fluctuating percentage 3%-98%	Generator monitor (GENMON)	C102A-1, CDC15 (VT)
GENCMD	Generator Command	Fluctuating percentage or small intermittent bursts 3%-98%	Generator communication (GENCOM)	C102A-2, CDC10 (BU/OG)
GENVDSD	Generator Voltage Desired	Voltage varies by vehicle needs - May be controlled by an output state control	—	—
GENFIL	Generator Fault Indicator Lamp	OFF if charging system is OK	—	—
GENCMD_LF	Generator Command Line Fault	NO FAULT if GENCOM circuit (GENCMD PID) is OK	—	—
GENMON_HZ	Generator Monitor Frequency	Frequency value	—	—
VPWR	Module Supply Voltage	Within 0.5 volt of battery voltage	—	—
RPM	Engine Revolutions Per Minute	Engine RPM - May be controlled by an output state control	—	—

Battery Management System

NOTICE: When any vehicle module is being programmed, connect an external battery charger to make sure the module programming is completed without the interruption due to the load shedding feature becoming active. The external battery charger must maintain a system voltage above 13 volts. This may require a charger setting higher than the lowest charge setting. The external battery charger negative connection must be made to an engine or vehicle chassis ground and not the negative battery terminal. If the connection is to the negative battery terminal, load shedding cannot be prevented from being invoked and module programming may be corrupted. After charging has begun, start the engine to clear any load shed states and then turn the engine off and proceed with programming.

This vehicle is equipped with load shed strategy. The BCM monitors the battery state of charge using the battery current sensor attached to the negative battery cable and the system voltage supplied to the BCM during 8 continuous hours of vehicle sleep time (key off with doors closed).

To maintain correct operation of the load shed system, ground any electrical devices or equipment to the chassis ground and not the negative battery terminal. A connection to the negative battery terminal may cause an inaccurate measurement of the battery state of charge and may cause incorrect load shed system operation.

Engine Off Load Shed

The BCM uses the battery current sensor to keep track of the battery state of charge. The battery current sensor is a Hall-effect sensor attached to the battery ground cable. When the engine is off and the BCM determines the battery state of charge is below 40%, or 10% of the charge has been drained, or 45 minutes have elapsed, a load shed message is sent over the CAN. This message turns off the audio/navigation system to save the remaining battery charge. Under this condition the FCDIM (without touchscreen controls) displays SYS OFF TO SAVE BATT or the FDIM (with touchscreen controls) displays BATTERY SAVER — SYSTEM OFF PLEASE START THE ENGINE to notify the driver that battery protection actions are active.

Engine off load shedding occurs when the engine is not running and the ignition is in the ACC, RUN or delayed accessory position. This load shed state clears once the vehicle has been started and the battery state of charge recovers. If the engine off load shed occurs, the audio/navigation system turns off.

When the ignition is in the RUN position and if load shed occurs, the IPC message center may display either TURN POWER OFF TO SAVE BATT (base message center) or TURN POWER OFF TO SAVE BATTERY (optional message center). The audio/navigation system shuts down after the message center displays the warning.

If a fault occurs with the battery current sensor or circuit(s), the only engine off load shed strategy that is active is a 45 minute timer. After 45 minutes have elapsed, the audio/navigation system turns off. To clear the load shed state, restart the engine.

For charging the vehicle battery, REFER to Section 414-01 .

If the vehicle battery is charged by connecting the battery charger to the battery negative terminal or the battery is replaced , carry out the BMS Reset using the scan tool. If the BMS Reset is not carried out, it takes approximately 8 hours for the BCM to learn the new battery state of charge. During this 8 hour period, the vehicle must be undisturbed, with no doors opened or keyless entry button presses. If the vehicle is used before the BCM is allowed to learn the new battery state of charge, engine off load shedding can still occur and a message may display.

If the vehicle battery is charged by connecting the battery charger to the engine or chassis ground , the BMS Reset using the scan tool is not necessary.

If the vehicle has been jump started , test the battery condition. REFER to Section 414-01 .

Engine Running Load Shed

When the BCM and/or PSCM voltage is low, with the engine running, the BCM sends a message to either minimize or shut down the climate controlled seats, rear defrost, heated mirrors and DATC blower motor to improve system voltage. Under this condition, the IPC message center displays either LOW BATTERY LESS FEATURES (base message center) or LOW BATTERY FEATURES TEMPORARILY TURNED OFF (optional message center) to notify the driver that battery protection actions are active.

There are 3 states of engine running load shed:

• Load shed 1
• Load shed 2 transient
• Load shed 2 continuous

Load Shed State	Entry Conditions	Impact to Features	Clear Conditions
Load shed 1	If vehicle speed is below 16 km/h (10 mph) Voltage to the PSCM is less than 11.5 volts. PSCM measures current draw greater than 0 amps. If vehicle speed is above 16 km/h (10 mph) Voltage to the BCM is less than 11.6 volts.	Climate controlled seats switch from HIGH to MED. If they are already at MED, the state does not change.	Voltage to the BCM is greater than 12.7 volts or the generator field duty cycle is less than 88%.
Load shed 2 transient	Voltage to the PSCM is less than 11.0 volts. PSCM measures current draw greater than 20 amps.	If equipped, climate controlled seats are disabled, but the indicators remain illuminated. If equipped, rear defrost and heated mirrors are disabled, but the indicator remains illuminated.	Voltage to the BCM is greater than 12.4 volts.
Load shed 2 continuous	Vehicle was in load shed 2 transient state for greater than 20 seconds.	If equipped, climate controlled seats are disabled and the indicators are off. If equipped, rear defrost and heated mirrors are disabled and the indicator is off. If equipped with DATC , the blower motor is reduced to 50% speed and the blower speed indicator reflects this. If equipped, DC/AC inverter (AC powerpoint) is disabled. The base message center displays LOW BATTERY LESS FEATURES. The optional message center displays LOW BATTERY FEATURES TEMPORARILY TURNED OFF.	Voltage to the BCM is greater than 12.4 volts for more than 60 seconds.

Component Description

Generator

The generator is equipped with an internal voltage regulator and if equipped, the radial arm is serviceable separately.

Battery Current Sensor

The battery current sensor is attached to the negative battery cable. It is supplied a 5–volt reference voltage and a ground from the BCM . The battery current sensor is a Hall-effect sensor that supplies a PWM feedback signal to the BCM .

Generator Current Sensor

The generator current sensor is attached to the generator B+ cable. It is supplied a 5–volt reference voltage and a ground from the PCM. The generator current sensor is a Hall-effect sensor that supplies a analog feedback signal to the PCM.

Powertrain Control Module (PCM)

The PCM receives input signals from sensors and other components (switches, relays). Based on this information, the PCM generates output signals to control various relays, solenoids and actuators.

---