Polarising a generator, at the regulator terminals, involves a simple procedure that ensures the generator and regulator read the same electrical polarity signal. In simple terms, the generator needs to remember how it was wired after it has been disconnected or replaced. If the regulator was recently replaced, the system still has to be polarised, since a disconnection has separated the system components. Failing to polarise can trip a generator or charging light in the system, and burn out the wiring circuit. Any repair person who has changed or disconnected the wires to the regulator, generator or alternator, needs to take a moment and polarise system.
- Skill level:
Things you need
- Engine Repair manual
- Battery charger (if applicable)
Make sure your tractor sits in park or neutral, with the emergency brake fully applied. Remove the ignition key. Make sure your battery has a full charge. Place the leads of a multimeter on the battery, hooking the positive, red lead of the meter to the positive terminal on the battery. Connect the negative, black lead of the meter to the negative terminal on the battery. Select the voltage scale with the knob. If the battery reads below 12 volts, charge the battery to at least 12.5 volts.
Open the bonnet cowl. Locate your regulator, by referring to your owner's engine manual. It will look like a small black box connected to the firewall or engine-side fender well. The regulator will have letters stamped on it, next to three wire locations. Note the "Arm", "Bat" and "Fld" wire designations, which stand for armature, battery and field. The wires lead to the generator, which should be similarly marked.
Read your repair manual to confirm that you must polarise the Bat and Fld terminals. This will be for the newer 12 volt engine models. Take a screwdriver and remove the small screws that hold down the field and battery eyelets on the regulator. Momentarily touch the two wires together until you see a small blue electric arc. Touch them for only a second or two. Reconnect the wire eyelets to the regulator terminals and tighten them with a screwdriver.
Read your repair manual to determine if you have an older 6-volt system. The markings on the regulator might read "Bat", "Fld" and "Gen." One other configuration will be "Bat", "Fld" and "Arm." In this case, you will use a screwdriver to disconnect the wire from the battery wire on the regulator, and the generator or armature wire on the regulator.
Momentarily touch the battery wire with the generator wire, or the armature wire, depending upon the letter designation. Look for the blue electrical arc. Refasten both wires to the regulator with the screwdriver.
Tips and warnings
- Instead of disconnecting the wires from the regulator, you can use a jumper wire to touch the poles on the regulator. Just make sure you do not touch any other wire while doing so, only prescribed wires.
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