Service Manual

Groundsmaster 7200/7210Page 5 - 26Electrical System
Dual Temperature Switch (Polar Trac
TM
Machines)
On machines equipped with Polar Trac
TM
, the dual tem-
perature switch includes two normally open circuits
used to monitor engine coolant temperature. These
switch circuits are the high temperature warning circuit
and t he high temperature shutdown circuit. The dual
temperature switch is attached to the engine water
pump housing (Fig. 34).
When engine coolant temperature rises to approximate-
ly 220
o
F (105
o
C), the high temperature warning circuit
closes. T his closed circuit causes the High Temperature
Warning Light on the console to illuminate and also pro-
vides an input to the Standard Control Module (SCM).
This input causes the SCM high temperature warning
LED to illuminate and the PTO implement to shut down.
If engine coolant temperature rises to approximately
240
o
F(115
o
C), the high temperature shutdown circuit
closes and provides an input to the Standard Control
Module (SCM). This input causes the SCM high temper-
ature shutdown LED to illuminate and the engine to shut
down.
The Standard Control Module (SCM) monitors the op-
eration of the dual temperature switch. If excessive cool-
ant temperature causes either switch circuit to close, the
appropriate LED on the SCM will be illuminated. The
switch and its circuit wiring should be tested using the
SCM before performing the following testing procedure.
Testing
1. Park machine on a level surface, lower implement,
stop engine, apply parking brake and remove key from
ignition switch. Open hood to gain a ccess to engine.
CAUTION
Make sure engine is cool before removing the
dual temperature switch from engine. Do not
open radiator cap or drain coolant if the radiator
or engine is hot. Pressurized, hot coolant can es-
cape and cause burns.
2. Lower the coolant level in the engine and remove the
dual temperature switch from the engine.
3. Put the end of the 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.
4. Check resistance of the switch with a multimeter
(ohms setting) as the oil temperature increases.
A. The high temperature warning circuit is normally
open and should close from 214
o
to 226
o
F(101
o
to
108
o
C).
B. The high temperature shutdown circuit is normal-
ly open and should close from 234
o
to 246
o
F(112
o
to
119
o
C).
5. Replace the switch if either of the specifications are
not met.
6. After testing is complete, install temperature switch
totheenginehousing.
A. Clean threads of housing and switch thoroughly.
Apply thread sealant to the threads of the switch.
B. Thread switch into the housing. Torque switch
from 22 to 28 ft- lb (29.4 to 39.2 N- m).
C. Reconnect harness wires to temperature switch.
7. Fill engine cooling system. Lower and secure hood.
1. Dual temp switch
2. Warning circuit
3. Shutdown circuit
Figure 34
1
2
3
1
Figure 35