Service Manual

Mid-Size Walk Behind Service Manual 8 - 7
ELECTRICAL
Testing
If the electric PTO clutch is not engaging or is
suspected as a cause of electrical problems, use the
following troubleshooting steps. The procedures will
help you determine if the clutch has failed or is the
cause of the electrical problem.
Coil Resistance Measurement
1. Disengage the PTO, set the parking, turn the
ignition key to OFF and remove the key.
2. Disconnect clutch wire connector.
3. Set the multimeter or volt/ohm meter to check
resistance (ohms).
4. Connect the meter lead wires to the wires in the
clutch connector (Figure 225).
Figure 225
mvc-887
5. The meter should read between 2.8 ohms and 3.2
ohms. If the reading is above or below these
readings, the field has failed and needs to be
replaced. If the reading is between these two
limits, proceed.
6. Measure the resistance between either of the
wires on the clutch connector to a ground on the
chassis. There should be no continuity. If there is,
the insulation in the coil has failed and the clutch
must be replaced (Figure 226).
Figure 226
mvc-891x
7. A final test is to connect a known good 12v battery
to the clutch. It should engage when the voltage is
applied and disengage when voltage is removed.
If the clutch passes the resistance test but does
not engage when a battery is applied there is
some type of mechanical failure.
Testing the Clutch Power Supply
Test the clutch as outlined above. If the clutch engages
using a jumper battery, you must look to the power
source.
Recoil Start Models
Begin by testing the alternator using the engine
manufacturers specifications. If your model uses a
bridge rectifier, obtain the DC voltage at the rectifier
terminals marked (+ and -); make a note of the
reading.