Small Engines (Lawn Mowers, etc.): blades do not engage, pto

Question
I have a husqvarna riding lawn mower.  In order to engage the blades, I pull a knob out.  When I pull the knob out, it will not engage.  Are there fuses, or any type of safety devices that might be stopping the knob from engaging the blades?

Answer
The first thing to check is that the clutch is getting battery voltage.  To do this, first check that the wires that come from the clutch are plugged into the wires that come from the switch.  If they are, then unplug them and with someone sitting on the mower seat, and with the engine running, have them turn the pto on while you measure the voltage at the switch side of the wire with a voltmeter.  Be sure to disconnect the plug to the clutch when doing this test.  If the blades were to come on while trying this, then it would be extremely dangerous.

If you can check this and let me know what you get we can go from there.  Thanks, PK.