The PTO clutch on a John Deere lawnmower is responsible for engaging the mower blades. The clutch bolts to the bottom of the engine crankshaft and uses a 12-volt current to run the system. When the engine is running, and the PTO switch on the dashboard is pulled up to the ON position, a 12-volt current is sent to the clutch, engaging a brake causing the blades to turn. When the Clutch malfunctions, the blades will no longer turn. This procedure will take 15 minutes to complete.
Park the lawnmower on a hard level surface. Remove the key from the ignition and set the parking brake.
Push the mower deck lever all the way forward to the lowest position. Locate the bar that connects the front of the mower deck to the front of the tractor frame. Pull the spring pin out of the bar at the front of the tractor frame. Pull the bar out of the hole. Slide the mower belt off the electric PTO clutch by hand.
Place the jack under the front of the frame and raise the tractor off the ground. Place the jack stands under each side of the frame in front of the wheels. Lower the jack until the frame is resting on the jack stands.
Disconnect the connector plugged into the right side of the PTO clutch to expose the terminals. Turn on the voltmeter and set it to 1x ohms scale. Put the positive lead and negative lead into terminals into the PTO clutch. The reading on the voltmeter should be 3.7 ohms. If it is not within this specification, the PTO clutch needs replacing.
Measure the resistance from each of the terminals with the positive lead from the voltmeter. Place the negative lead from the voltmeter to a ground (bare metal). The resistance should read the same 3.7 ohms. If the readings differ, there is a short in the wiring harness.