Voltage regulator test 1997 Harley Davidson FLHR Road King

To test your regulator, first charge your battery to full charge. You'll need a DVOM (digital volt ohm meter). Connect the DVOM "across" the battery by connecting the red meter lead to the positive post of the battery and the black meter lead to the negative post of the battery. Put the meter's function selector switch in DC VOLTS, 50 VOLT RANGE. Start the engine and bring it to a high idle. After about a minute or so, you're meter should read between 14.5 and 15.0 volts. If not, proceed to the next step.

If you are not getting the correct voltage to keep your battery charged, you need to check the output of the stator. Look on the front of the engine near the end of the oil filter and you'll see the plug from your voltage regulator plugged up there. Unplug the plug and look down into the engine side of the plug and you'll see two metal contacts. This is where we are going to test the output of you alternator. First, put your meter's function switch to AC VOLTAGE, 50 VOLT RANGE. Notice that we are testing for AC voltage as opposed to DC like we did last in the last test. This means it doesn't make any difference which meter lead goes to which contacts. Start the engine and put one of the meter's probes on each of the metal contacts. Make sure you do not touch the meter probe to each other or to the engine case. Bring the engine to a high idle and your meter should read at least 30 volts AC voltage.

If you do not have the 30 volts AC at the engine, your stator is bad. If you do have at least thirty volts at the alternator but less than 13.0 volts at the battery, your regulator is bad. Make sure your regulator is properly grounded where it bolts to the frame. I usually put one of those "star lockwashers" between the regulator and the frame on both bolts to make sure I've got a good ground. If the regulator is not grounded properly, it won't work.

Good Luck
Steve