The direction of rotation on a 12-volt motor will alternate with a change in polarity. Manually changing the polarity of a DC motor involves swapping the positive and negative cable positions on the battery. Removing installed wires connected between the motor and the battery to change rotation is cumbersome; you need another method of reversing the polarity of the motor. Installing a six-terminal toggle switch between the battery and the motor will allow you to reverse the direction of the 12-volt motor without manually disconnecting and moving wires.
Loosen the screws on the back of a six-terminal switch with a Phillips screwdriver.
Cut one piece of red wire and one piece of black wire long enough to reach between the motor and the location of the six-terminal switch with a pair of wire cutters. Strip 1/2 inch of protective sheathing from each end of the two wires.
Bend the exposed copper in a U shape with the gripping end of a pair of wire cutters. Slide one hooked end of the red copper wire to the lower right terminal of the switch. Tighten the switch screw with a Phillips screwdriver. Connect one hooked end of the black wire to the lower left terminal of the switch using the described method. Connect the other end of the red wire to the positive terminal of the 12-volt motor and the other end of the black wire to the 12-volt motor's negative terminal.
Cut and prepare another length of both red and black wires to reach the 12-volt motor. Secure one end of the red wire to the upper left terminal of the switch and one end of the black wire to the upper right switch terminal. Connect the loose end of the red wire to the positive motor terminal and the loose end of the black wire to the negative motor terminal.
Set the switch to the middle position.
Cut and prepare a piece of red and a piece of black wire to reach from the switch to the battery. Connect one end of the red wire to the middle left terminal. Connect the other end of red wire to the positive terminal of the 12-volt battery. Connect one end of the black wire to the middle right terminal of the switch. Hook the other end of the black wire to the negative battery terminal.
Flip the switch to the up position to start the motor. Move the switch to the middle position. Allow the motor to stop rotating. Push the switch to the down position to rotate the motor in the opposite direction.