Test Procedure

Check Voltage Drop In "A" Circuit

Turn ignition switch to RUN position. Measure voltage between test point "A" on voltage regulator and positive (+) battery post. See Figure. Is voltage drop less than 0.25 volts? If yes, then go to next step. If not, then check fuse "J" (10 amp), replace if overloaded. If fuse is okay, then check for excess voltage drop in Yellow/White wire between fuse "J" and voltage regulator terminal "A". See WIRING DIAGRAMS . Repair as necessary, then retest system for normal operation.

NOTE: Voltage regulator must be connected to wiring harness for this test.

Check Voltage Drop In "I" Circuit
Measure voltage at wiring harness "I" terminal. See Figure. Is voltage greater than 1 volt? If yes, then go to next step. If not, then service open in Light Green/Red wire between Instrument Panel connector C256 terminal No. 10. See Figure. See WIRING DIAGRAMS . When repair is complete, retest system for normal operation.

Check For Poor Grounds

Check for poor ground connections between voltage regulator and generator, battery and engine, or engine and battery. Are all ground connections clean and tight? If yes, then go to next step. If not, then service grounds as required. Retest system for normal operation.

Check For Grounded Slip Ring

Remove generator from vehicle. See GENERATOR under REMOVAL & INSTALLATION. Remove voltage regulator. See VOLTAGE REGULATOR under REMOVAL & INSTALLATION. Measure resistance from each generator slip ring to the generator housing. Is resistance from either slip ring to housing less than 200 ohms? If yes and grease or dirt has accumulated near the slip rings, clean and recheck. If resistance is still less than 200 ohms, replace generator. If resistance is more than 200 ohms, replace voltage regulator. Retest system for normal operation.