Temperature Sender - Toro Workman HDX Auto Service Manual

Temperature Sender

The temperature sender is threaded into a fitting in the
top of the engine cylinder casting (Fig. 35). The resist-
ance of the temperature sender reduces as the engine
coolant temperature increases. This resistance change
is used by the instrument cluster to display engine oper-
ating temperature. There is a violet wire attached to the
sender.
Testing
1. Park machine on a level surface, raise bed, stop en-
gine, apply parking brake and remove key from ignition
switch.
2. Install bed support on bed lift cylinder to prevent bed
from lowering.
CAUTION
Make sure engine is cool before removing the
temperature switch.
3. Lower the coolant level in the engine, remove wire
harness connector from temperature sender and re-
move the sender from the engine.
4. Put switch in a container of oil with a thermometer
and slowly heat the oil (Fig. 36).
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 resis-
tance of the meter and test leads. Subtract this value
from from the measured value of the component you are
testing.
5. Check resistance of the sender with a multimeter
(ohms setting) as the oil temperature increases. Re-
place sender if specifications are not met.
COOLANT TEMP TEMP SENDER RESISTANCE
100F (38C)
160F (71C)
200F (93C)
220F (105C)
Electrical System
460 ohms (approximate)
140 ohms (approximate)
54 to 78 ohms
50 ohms (approximate)
6. Install temperature sender to the water pump hous-
ing.
A. Clean threads of water pump housing and switch
thoroughly. Apply thread sealant to the threads of the
switch.
B. Install sender into the water pump housing and
tighten. Torque from 16 to 20 ft−lb (22 to 27 N−m).
C. Connect harness violet wire to switch.
7. Fill engine cooling system.
8. Remove bed support from cargo bed lift cylinder and
lower bed.
FRONT
1. Engine flywheel
Page 6 − 26
2
Figure 35
2. Temp sender
Figure 36
Workman HDX Auto
1