NOTE: The following test assumes alternator is satisfactory.

Disconnect variable resistor and remove link bridging regulator negative and "F" terminals. With remainder of test circuit still connected, start engine and run up to 3200 RPM (6000 alternator RPM), until ammeter registers output current of less than 10 amps. Voltmeter should then read 13.6-14.4 volts. Any variation necessitates regulator replacement.
If regulator is still shown to be satisfactory, disconnect entire external test circuit and reconnect alternator harness connector. Attach a low-range voltmeter between either positive alternator terminal and positive battery terminal.
Turn on headlights, start engine and increase engine speed to 3200 RPM. Record voltmeter reading. Transfer voltmeter connection to alternator frame and negative battery terminal. Record reading. If reading exceeds 0.5 volt on positive side or 0.25 volt on negative side, there is a high resistance in charging circuit which must be traced and corrected. See further testing on Overhaul procedure.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Regulator Test