12
Test Procedures
TROUBLESHOOTING AND ELECTRICAL
SYSTEM: DIESEL VEHICLES
2113
Figure 12-15
Check Power To Fan Relay
2114
Figure 12-16
Fan Relay Contact Test
5.
If the fan runs constantly, even with the key switch OFF, remove the relay. If fan stops, the relay contacts
have failed closed and the relay must be replaced.
TEST PROCEDURE 10 – Thermostat Switch
See General Warnings, Section 1, Page 1-2.
The thermostat switch houses two independent switches. Each switch closes the circuit between the thermostat
housing (effectively frame ground) and the appropriate wire of the thermostat switch (white or black).
THERMOSTAT SWITCH
CONTACT OPERATION:
WIRE
COLOR
FUNCTION
CLOSE ON RISE
OPEN
White
Radiator Fan
187 °F to 198 °F (86 °C to 92 °C)
165 °F (74 °C)
Black
Temperature Warning Light
216 °F to 226 °F (102 °C to 108 °C)
185 °F (85 °C)
The fan relay activates the radiator fan when the engine coolant reaches a temperature range of 187 °F to 198 °F
(86 °C to 92 °C) and closes the fan thermostat switch.
The engine coolant thermostat switch provides a ground to the coolant temperature warning light when the engine
block reaches a temperature range of 216 °F to 226 °F (102 °C to 108 °C) and closes the thermostat switch.
See
following NOTE.
NOTE:
Keep the battery connected during this test procedure.
1.
Disable the vehicle.
See Disabling the Vehicle on page 1-3.
2.
Drain coolant from engine.
See Engine Coolant Change, Section 18, Page 18-1. See following WARNING.
WARNING
• Hot! Coolant system is pressurized. Do not remove thermostat switch while engine is hot.
3.
Disconnect the two-pin connector between the thermostat switch and the wire harness
4.
Test for failed switches in closed condition.
Page 12-20
2013 Carryall 295/XRT 1550 Maintenance and Service Manual
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