Usually, the switch terminals are labelled ;-
G - Ground
B - Battery
S- Starter (Solenoid) (ON when switch turned to 'Start')
L - Load (Accessories - lights, blade clutch, etc)
M - Magneto (Grounded when switch 'Off', open otherwise)
If your's is not, email a decent picture of the switch and I'll try to identify the connections for you.
Phil Saunders, June 2008
