Toro Greensmaster 3120 Service Manual page 210

Identifying the Relays and their Functions (continued)
Testing the Relays
Electrical System: Testing the Electrical Components
Lower Relay (K5) When energized by the solid state timer, the lower relay
allows current flow to the hydraulic solenoid valve coils S2 and S4 causing the
cutting units to lower. The lower relay is located under the control panel on the
left side of the operator seat.
Raise Relay (K6) When energized by the joystick raise switch, the raise relay
allows current flow to hydraulic solenoid valve coils S2 and S3 causing the
cutting units to raise. The raise relay is located under the control panel on the
left side of the operator seat.
Backlap Relay (K7) (machines with backlap only) The backlap relay is only
installed on machines with the backlap feature. The relay is energized by the
backlap switch when the backlap lever is in the R position. The backlap relay
prevents the cutting units from engaging while the engine is cranking if the
backlap lever is in the R position. The backlap relay is located near the functional
control lever.
Charge Circuit Relay (K8) The charge circuit relay is energized when the key
switch is in the Run or Start position. The charge circuit relay allows output from
the engine alternator to reach the machine electrical circuits. The charge circuit
relay is located under the front of the operator seat.
1. Park the machine on a level surface and lower the cutting units. Make sure
the engine is off and the key switch is in the OFF position.
2. Remove the control panel shield.
Note: Since all of the relays used on the machine are identical, use the tag
on the wire harness at the relay connector to help locate the desired relay.
3. Locate the relay to be tested and disconnect wire harness connector from
the relay. If desired, remove the relay from the machine for testing.
4. Use a multimeter (ohms setting) to measure the resistance between the
following relay terminals; refer to
A. Continuity should exist between terminals 87a and 30.
B. There should not be continuity between terminals 87 and 30.
C. Resistance between terminals 86 and 85 (relay coil) should be from 80
to 90 ohms.
5. Connect a multimeter (ohms setting) to relay terminals 30 and 87. Ground
terminal 86 and apply +12 VDC to terminal 85. The relay should make and
break continuity between terminals 30 and 87 as 12 VDC is applied and
removed from terminal 85.
6. Connect a multimeter (ohms setting) to relay terminals 30 and 87a. Ground
terminal 86 and apply +12 VDC to terminal 85. The relay should make and
break continuity between terminals 30 and 87a as 12 VDC is applied and
removed from terminal 85.
7. Replace the relay if necessary.
8. If the relay tests correctly and a circuit problem still exists, check the wire
harnesses; refer to
9. If previously removed for testing, install the relay and connect the wire
harness to the relay.
10. Install the control panel shield before returning the machine to service.
Figure 92.
Appendix A (page A–1).
Page 5–24 Greensmaster 3120
17230SL Rev C