JLG 450A_AJ Series II Service Manual - Manual (Page 166)

SECTION 3 - CHASSIS & TURNTABLE
3-126 – JLG Lift – 3121290
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 operating at a
speed greater than defined in the diagnostic calibration.
• Corrective Action(s)- Sound audible warning or illuminate
secondary warning lamp, disable adaptive learn fueling
correction during active fault. Recommend a power derate
2 and/or a forced idle or engine shutdown to protect
engine from possible damage.
• Non-emissions related fault
The Engine Coolant Temperature sensor is a thermistor (tem-
perature sensitive resistor) located in the engine coolant.
Some engines use a CHT sensor that is located in the coolant
in the cylinder head. Some engines use an ECT (Engine Cool-
ant 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 tem-
perature. 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 troubleshooting
procedures for that fault as it may have caused “ECT Higher
Than Expected 2.”
If cooling system uses an air-to-water heat exchanger (radia-
tor) 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 gly-
col/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.