How to Change Voltage Regulator on the Alternator

Once you’ve concluded (after measurement with a multimeter) that the alternator isn’t giving enough output, the first thing you should do is change the voltage regulator. When the regulator is faulty, the output can be under 13 V (a) or above 14.5 V (b) thus causing:

• lack of power output to the installation and no refill of the battery
• “overfilling” or too much output causing the alternator-stator to burn out or possible damage to the battery.

The first thing you should do is take off the alternator. You can see how to do that in the “Taking off the alternator” tutorial. In some rare cases, you can do the replacement while the alternator is on the engine, but I don’t recommend that. You can cause damage to the regulator brushes. Once you’ve taken off the alternator here’s what you do:

1. The voltage regulator is held by two screws. Take them off with a screwdriver.
2. Take out the old regulator.
3. Clean all the contacts with sandpaper. The contacts are :

• within the alternator, which makes the alternator-regulator contact
• regulator- alternator housing contact (makes the “-” connection)

1. Put the new regulator on. Be very careful with the brushes. They’re longer when they are new, so take your time and make sure that you have put it in properly.
2. Tighten the screws. Rotate the rotor, there should only be the sound of brush contact to the rotor.

Return the alternator back on the engine. Make a measurement with the multimeter to sure that you did a proper job.