DTC P0621: Gen Terminal L Circuit: Description

PCM controls generator charging by supplying generator a control voltage of 5 volts whenever ignition is on or engine is running. This control voltage is necessary for generator to charge once engine has started and generator begins to spin. Ignition on, engine off, generator will ground control voltage through pull-down resistor. Voltage on terminal "L" circuit with circuit intact will be 1.0-1.5 volts. When engine is started and generator begins to charge, generator will open circuit (still using 5 volt control voltage) signaling PCM that generator is charging. DTC sets when engine is running and voltage at PCM generator terminal "L" output is low, indicating generator is not charging or circuit is shorted to ground. If this condition occurs, PCM will send a message to instrument panel cluster over Class II link to turn on Charge (battery) telltale.