Principles of Operation
CHARGING SYSTEMThis vehicle is equipped with a powertrain control module (PCM) controlled charging system. The PCM controlled charging system is a system whereby the PCM determines the optimal voltage setpoint for the charging system and communicates this information to the voltage regulator. The PCM controlled charging system is unique in that it has two unidirectional communication lines between the PCM and the generator/regulator. Both of these communication lines are pulse-width modulated. The generator communication (Alternator Load Feed Forward, or ALFF) line communicates the desired setpoint from the PCM to the voltage regulator and the generator monitor (I-line) communicates the generator load and error conditions to the PCM. The third pin on the voltage regulator, the A-line, is a dedicated battery voltage sense line.
Circuit Description
B+ Output Terminal Circuit 38 (BK/OG)
Generator output voltage is supplied through the battery positive (B+) output terminal on the rear of the generator to the battery and the electrical system.
Circuit 35 (OG/LB)
This is the A-line battery voltage sense circuit and is used to sense battery voltage.
Circuit 1930 (TN/LG)
This is the ALFF (Alternator Load Feed Forward) circuit. The PCM determines the optimal voltage setpoint for the charging system and communicates the information to the voltage regulator via the ALFF circuit.
Circuit 1931 (BN/PK)
The I-line circuit communicates the generator load and error conditions to the PCM. The PCM will turn on the charging system warning indicator if there is an error condition.