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Home >> Ford Truck >> 2012 >> Explorer FWD L4-2.0L Turbo >> Repair and Diagnosis >> Starting and Charging >> Charging System >> Description and Operation >> System Operation

System Operation




Charging System

System Operation

System Diagram





Network Message Chart

Module Network Input Messages - BCM (Body Control Module)





Module Network Input Messages - IPC (Instrument Panel Cluster)





Module Network Input Messages - PCM (Powertrain Control Module)






Charging System

The PCM (Powertrain Control Module)-controlled, or Smart Charge charging system determines the optimal voltage setpoint for the charging system and communicates this information to the voltage regulator. The Smart Charge charging system is designed to set 1 of 6 DTCs (Diagnostic Trouble Codes) any time a charging system fault is present. All of the DTCs (Diagnostic Trouble Codes) can set continuous faults, but not all DTCs (Diagnostic Trouble Codes) set as on-demand faults.





a Requires vehicle speed above 8 mph

This system uses 2 communication lines between the PCM (Powertrain Control Module) and the generator/voltage regulator. Both of these communication lines use PWM (Pulse-Width Modulation). The generator communication (GENCOM) line communicates the desired setpoint from the PCM (Powertrain Control Module) to the voltage regulator. The generator monitor (GENMON) line communicates the generator load and error conditions to the PCM (Powertrain Control Module). The GENCOM command is only sent by the PCM (Powertrain Control Module) when it is necessary to adjust the voltage setpoint. If the setpoint does not need to be changed, several seconds may elapse between PCM (Powertrain Control Module) GENCOM commands. This normal operation appears in the PID (Parameter Identification) 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 (Powertrain Control Module) simultaneously controls and monitors the output of the generator. When the current consumption is high or the battery is discharged, the PCM (Powertrain Control Module) 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 (Powertrain Control Module) uses a signal from the IAT (Intake Air Temperature) sensor to adjust the charging voltage according to the battery temperature. The PCM (Powertrain Control Module) also uses other inputs to control the charging system voltage such as the VSS (Vehicle Speed Sensor) and engine coolant temperature. The voltage setpoint is calculated by the PCM (Powertrain Control Module) and communicated to the voltage regulator by the GENCOM circuit based on the needs of the vehicle and the conditions.

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

The PCM (Powertrain Control Module) reports any charging system faults and sends a message through the HS-CAN (High Speed Controller Area Network) to the BCM (Body Control Module). The BCM (Body Control Module) controls the charging system warning indicator by sending a message over the MS-CAN (Medium Speed Controller Area Network) to the IPC (Instrument Panel Cluster). The IPC (Instrument Panel Cluster) then controls charging system warning indication based on the message from the PCM (Powertrain Control Module) through the BCM (Body Control Module). The status of the PCM (Powertrain Control Module) charging system warning indicator and/or message is confirmed by viewing PCM (Powertrain Control Module) PID (Parameter Identification) generator fault indicator lamp (GENFIL). Any charging system fault detected by the PCM (Powertrain Control Module) results in 1 or more DTCs (Diagnostic Trouble Codes) being set and the PID (Parameter Identification) GENFIL having a status of On. If equipped with a charging system warning indicator, the IPC (Instrument Panel Cluster) turns the indicator on or off. If equipped with a message center, the IPC (Instrument Panel Cluster) 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 (Revolutions Per Minute) 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 (Revolutions Per Minute) 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 (Parameter Identifications) and their associated descriptions used in the charging system diagnosis are listed below:






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 (Body Control Module) 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 (Body Control Module) 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 (Body Control Module) 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 (Body Control Module) 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 (Controller Area Network). This message turns off the audio/navigation system to save the remaining battery charge. Under this condition the FCDIM (Front Control/Display Interface Module) (without touchscreen controls) displays SYS OFF TO SAVE BATT or the FDIM (Front Display Interface Module) (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 (Instrument Panel Cluster) 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 Battery Charging .

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 (Battery Monitoring System) Reset using the scan tool. If the BMS (Battery Monitoring System) Reset is not carried out, it takes approximately 8 hours for the BCM (Body Control Module) 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 (Body Control Module) 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 (Battery Monitoring System) Reset using the scan tool is not necessary.

If the vehicle has been jump started, TEST the battery condition. REFER to Diagnostic Routine A: Battery Condition Test Pinpoint Tests.

Engine Running Load Shed

When the BCM (Body Control Module) and/or PSCM (Power Steering Control Module) voltage is low, with the engine running, the BCM (Body Control Module) sends a message is to either minimize or shut down the climate controlled seats, rear defrost, heated mirrors and DATC (Dual Automatic Temperature Control) blower motor to improve system voltage. Under this condition, the IPC (Instrument Panel Cluster) message center will 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




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