Temperature Sender - Toro GroundsmasterR 4300-D Service Manual

Temperature Sender

The temperature sender is attached to the water pump
housing on the engine and has a gray wire attached to
it (Fig. 48). The resistance of the temperature sender re-
duces as the engine coolant temperature increases.
The changing resistance of the temperature sender sig-
nals the console temperature gauge to indicate engine
coolant temperature level during machine operation.
When coolant temperature rises to approximately
o o
221 F (105 C), temperature sender resistance causes
the temperature gauge to provide an input to the TEC
controller. This controller input causes the high temper-
ature warning light to illuminate and the cutting decks to
shut down. The temperature gauge, temperature send-
er and circuit wiring should be tested as a controller in-
put with the Diagnostic Display (see Special Tools and
Troubleshooting in this chapter).
If the excessive coolant temperature caused the control-
ler to shut down the cutting decks, the Diagnostic light
can be used to identify the fault (see Diagnostic Light in
the Troubleshooting section of this chapter).
Testing
1. Park machine on a level surface, lower cutting
decks, stop engine, apply parking brake and remove
key from ignition switch. Open and support hood.
CAUTION
Make sure engine is cool before removing the
temperature sender from engine.
2. Lower the coolant level in the engine, remove wire
harness connector from temperature sender and re-
move the sender from the engine.
3. Put the end of the sender in a container of oil with a
thermometer and slowly heat the oil (Fig. 49).
CAUTION
Handle the hot oil with extreme care to prevent
personal injury or fire.
NOTE: Prior to taking resistance readings with a digital
multimeter, short the meter test leads together. The me-
ter will display a small resistance value (usually 0.5
ohms or less). This resistance is due to the internal re-
sistance of the meter and test leads. Subtract this value
from from the measured value of the component you are
testing.
Groundsmaster 4300--D
4. Check resistance of the sender with a multimeter
(ohms setting) as the temperature increases. Replace
sender if specifications are not met.
COOLANT TEMP
o o
100 F (38 C)
o o
160 F (71 C)
o o
200 F (93 C)
o o
221 F (105 C)
5. After testing, install sender to the engine housing.
A. Clean threads of housing and sender thoroughly.
Apply a light coating of thread sealant to the threads
of the sender.
B. Thread sender into the housing. Torque sender
from 16 to 20 ft- -lb (22 to 27 N- -m).
C. Connect wire harness connector to sender.
6. Fill engine cooling system (see Radiator Installation
in the Service and Repairs section of Chapter 3 -- Kubota
Diesel Engine).
7. Lower and secure hood.
1
1. Temperature sender
Page 5 - - 39
TEMP SENDER RESISTANCE
460 ohms (approximate)
140 ohms (approximate)
54 to 78 ohms
50 ohms (approximate)
Figure 48
Figure 49
Electrical System