JLG 450A_AJ Series II Service Manual - Manual (Page 221)

SECTION 3 - CHASSIS & TURNTABLE
3121180 – JLG Lift – 3-171
DTC 217- ECT Higher Than Expected 2
• Engine Coolant Temperature Sensor.
• Check Condition-Engine Running.
• Fault Condition-Engine Coolant Temperature reading
or estimate greater than the stage 2 limit when operat-
ing at a speed greater than defined in the diagnostic
calibration.
• Corrective Action(s)- Sound audible warning or illumi-
nate secondary warning lamp, disable adaptive learn
fueling correction during active fault. Recommend a
power derate 2 and/or a forced idle or engine shut-
down to protect engine from possible damage.
• Non-emissions related fault
The Engine Coolant Temperature sensor is a thermistor
(temperature sensitive resistor) located in the engine cool-
ant. Some engines use a CHT sensor that is located in the
coolant in the cylinder head. Some engines use an ECT
(Engine Coolant Temperature) sensor that is located in the
coolant near the thermostat. If the engine is equipped with
a CHT sensor then the ECT value is estimated. If equipped
with an ECT sensor then the CHT value is estimated. The
ECM provides a voltage divider circuit so when the sensor
reading is cool the sensor reads higher voltage, and lower
when warm.
This fault helps protect the engine in the event of over
temperature. When coolant exceeds x deg. F and engine
RPM exceeds y RPM for the latch time this fault will set.
Diagnostic Aids
If “ECT High Voltage” fault is present, follow troubleshoot-
ing procedures for that fault as it may have caused “ECT
Higher Than Expected 2.”
If cooling system uses an air-to-water heat exchanger
(radiator) and fan:
• Check radiator has a proper amount of ethylene glycol/
water and is not leaking.
• Make sure there is no trapped air in the cooling path.
• Inspect cooling system (radiator and hoses) for cracks
and ensure connections are leak free.
• Check fan is operating properly.
• Check thermostat is not stuck closed.
If cooling system uses a water-to-water heat exchanger:
• Check heat exchanger has proper amount of ethylene
glycol/water and heat exchanger is not leaking.
• Make sure there is no trapped air in the cooling path.
• Inspect cooling system (radiator and hoses) for cracks
and connections are leak free.
• Check raw water pickup is not blocked/restricted by
debris and hose is tightly connected.
• Check thermostat is not stuck closed.
• Check raw water pump/impeller is intact and not
restricted.