Fix Honda alternator that doesn’t charge on start up
Some Honda owners have had their vehicle’s charging system tested and discovered that their Honda alternator doesn’t charge on start up. So they’ve forked out the dough and replaced it only to find the new ones doesn’t charge either. If you don’t understand the system, you can be easily fooled by the alternators operation. The voltage regulator on many Honda’s is incorporated into the engine control unit (ECU). The ECU is smart enough to determine whether the battery needs charging or not. If there are no electrical demands present, the ECU TURNS off the field current to the alternator, which does NOT turn on the charge light. If you test the system during these low demand conditions, you can be fooled into thinking that the alternator is bad. Always turn on headlights or the blower motor to force the ECU into providing field current to energize the alternator and THEN perform your tests.
© 2012 Rick Muscoplat