Principles Of Operation
Principles of Operation
The PCM-controlled charging system, 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 9 DTCs any time a charging system fault is present. All of the DTCs can set continuous faults, but not all DTCs set as on-demand faults.
This system uses a dedicated Local Interconnect Network (LIN) communication circuit. The generator uses this LIN (Local Interconnect Network) circuit to communicate the desired setpoint from the PCM to the voltage regulator. The generator also uses this LIN (Local Interconnect Network) circuit to communicate the generator load and error conditions to the PCM.
The PCM simultaneously controls and monitors the output of the generator. When the usage of current 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 of the electrical loads that are required. 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 the measurement from the Intake Air Temperature (IAT) sensor to adjust the charging voltage according to the battery temperature. The PCM also uses other inputs to control charging system voltage such as the Vehicle Speed Sensor (VSS) and Engine Coolant Temperature (ECT) sensor. The voltage setpoint is calculated by the PCM and communicated to the voltage regulator by the LIN (Local Interconnect Network) circuit based on the needs of the vehicle and the operating 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 desired voltage.
The PCM controls the charging system warning indicator by sending a message over the High Speed Controller Area Network (HS-CAN) to the Instrument Panel Cluster (IPC) module. The IPC (Instrument Panel Cluster) module controls the charging system warning indication based on the message from the PCM. The IPC (Instrument Panel Cluster) module controls the charging system indication based on the message from the PCM, turning it on or off. If equipped with a Front Control/Display Interface Module (FCDIM) (message center), the IPC (Instrument Panel Cluster) module displays a CHECK CHARGING SYSTEM message. When the ignition is on and the engine is off on vehicles equipped with a message center, the CHECK CHARGING SYSTEM message may not be displayed. For additional information regarding the IPC (Instrument Panel Cluster) module, refer to Instrument Panel, Gauges and Warning Indicators. For additional information regarding the FCDIM (Front Control/Display Interface Module), refer to Accessories and Optional Equipment.
Under certain circumstances the charging system may have a concern but still keep the battery charged and the vehicle running. The LIN (Local Interconnect Network) normally initiates charging from the PCM, but the generator may continue charging when a fault is present on this circuit. If the engine is operated at greater 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 is operated at greater 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 Chart
