Toro Groundsmaster 4300-D Service Manual page 294

Testing the Relays with 4 Terminals
Electrical System: Testing the Electrical Components
The main power and glow relay are attached to a frame bracket under the hood
next to the hydraulic pump driveshaft
1. Park the machine on a level surface, lower the cutting decks, shut off the
engine, set the parking brake, and remove the key from the key switch.
2. To ensure that the machine operation does not occur unexpectedly,
disconnect the negative (-) cable from the battery and then disconnect the
positive (+) cable from the battery; refer to
3. Locate the relay that is to be tested.
4. Disconnect the wire harness electrical connector from the relay. Remove the
relay from the mounting bracket for testing.
Note: Before taking the small resistance readings with a digital multimeter,
short the multimeter test leads together. The meter displays a small
resistance value (usually 0.5 ohms or less). This resistance is because of the
internal resistance of the multimeter and test leads. Subtract this value from
the measured value of the component that you are testing.
5. Check the coil resistance between the terminals 85 and 86 with a multimeter
(ohms setting). The resistance must be approximately 72 ohms
6. Connect the multimeter (ohms setting) leads to the relay terminals 30 and
87. Then ground terminal 85 and apply +12 VDC to terminal 86. The relay
should make and break the continuity between the terminals 30 and 87 as
+12 VDC is set and removed from terminal 86
7. Disconnect the voltage and leads from the relay terminals.
8. Replace the relay if testing determines that the relay is damaged.
9. If the relay testing is correct and a circuit problem still exists, check the
platform wire harness; refer to the Electrical Schematic and Wire Harness
Drawings/Diagrams in
10. Secure the relay to the mounting bracket and connect the wire harness
electrical connector to the relay.
11. Connect the positive (+) cable to the battery and then connect the negative
(-) cable to the battery; refer to
(Figure 176).
Servicing the Battery (page
Appendix A (page A–1).
Servicing the Battery (page
Page 5–70
(Figure
(Figure 177).
5–94).
Groundsmaster
16226SL Rev C
5–94).
177).
® 4300-D