Service Manual

Workman HD Series Page 8 − 25 Electrical System
Temperature Sender (Workman HDX and HDX−D)
Liquid cooled vehicles have a temperature sender
threaded into the water pump housing on the engine
(Fig. 34). The resistance of the temperature sender re-
duces as the engine coolant temperature increases.
This resistance change is used by the instrument cluster
to display engine operating temperature. There is a yel-
low 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. 35).
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 temperature increases. Replace
sender if specifications are not met.
COOLANT TEMP
TEMP SENDER RESISTANCE
100F (38C) 405 to 495 ohms
160F (71C) 120 to 140 ohms
220F (105C) 44 to 48 ohms
1. Water pump housing
2. Temp sender
3. Thermal fan switch
(HDX−D only)
Figure 34
2
1
3
Figure 35
6. Replace temperature sender if necessary.
7. Install switch to the water pump.
A. Clean threads of water pump housing and switch
thoroughly. Apply thread sealant to the threads of the
switch.
B. Install switch into the water pump housing and
tighten.
C. Connect yellow wire harness wire to switch.
8. Fill engine cooling system.
9. Remove bed support from lift cylinder and lower bed.
Electrical
System