Unplug harness connector from regulator at rear of alternator. Connect ohmmeter between regulator "A" and "F" terminal screws.
If resistance is not greater than 2.4 ohms, a short in the field circuit or a grounded rotor coil is indicated. Replace alternator. If resistance is greater than 2.4 ohms, go to next step.
Reconnect regulator wiring plug. Connect negative voltmeter lead to ground. Contact positive voltmeter lead to regulator "A" terminal screw. If voltmeter does not indicate battery voltage, repair open or high resistance in "A" circuit wiring. Perform load test after repairs.
If battery voltage is indicated at "A" terminal screw, ensure ignition switch is in OFF position. Connect positive voltmeter lead to regulator "F" terminal screw. If battery voltage is present, go to step 4). If battery voltage is not present, replace alternator.
Turn ignition switch to ON position (engine off). With voltmeter negative lead to ground, contact positive lead of voltmeter to regulator "F" terminal screw. If voltmeter indicates 2 volts or less, go to next step. If voltage is greater than 2 volts, check circuit between "I" terminal and ignition switch. Repair if necessary.
If "I" circuit is okay, replace regulator. Perform LOAD TEST after repair.
Start engine and run at 2000 RPM with headlights on. Measure voltage at "B+" terminal of alternator and at alternator feed wire at starter relay. If voltage readings differ by more than 0.5 volt, repair high resistance or open in wire between "B+" terminal and junction near starter relay.
If alternator still does not charge sufficiently, connect a jumper wire from regulator "F" terminal screw and ground it to rear housing. If output voltage increases to 13-15 volts, replace regulator. If output voltage does not increase to at least 13 volts replace alternator.
Sunday, August 23rd, 2009 AT 7:06 AM