The Stovebolt Site Forums The Parking Lot Big Bolts 2 different polarizing instructions??

Got a new voltage regulator for a '48 GMC fc303 1.5 ton that still has the original 6 volt system.

The instructions in the box said to polarize by touching the jumper wire to ARM and BAT but not to touch the FLD.

Problem is, We have a reproduction owners manual that says (page 97) to remove wire from FLD at the generator and touch FLD terminator on generator and BAT termonal on egulator with a jumper wire.

Which way is right on a Positive ground system??

It depends on whether you've got an "A" circuit or a "B" circuit generator. Most Delco generators have an A circuit which means the regulator provides a ground for the field current. On the B circuit, which was used on Ford products mostly, the field coils are grounded inside the generator, and the regulator provides a voltage to excite the fields, not a ground.

The simplest way to tell the difference is to look inside the generator. If a small-diameter wire taps off of the Armature terminal and goes to the Field coils, you've got an A circuit. If one end of the Field coil winding goes to ground, it's a B circuit.

Polarize an A circuit generator by flashing the Battery to Armature terminal at the regulator with a jumper. Nothing needs to be disconnected. Polarize a B circuit generator by removing the Field wire at the regulator, and touching it to the Battery terminal.
Jerry