JLG 510AJ Service Manual - Manual (Page 143)

SECTION 3 - CHASSIS AND TURNTABLE
3121181 – JLG Lift – 3-101
DTC 117- ECT/CHT Low Voltage
• Engine Coolant Temperature Sensor
• Check Condition-Engine Running
• Fault Condition-CHT/ECT sensor voltage less than the limit
defined in the diagnostic calibration
• Corrective Action(s)- Sound audible warning or illuminate
secondary warning lamp, disable adaptive learn fueling
correction during active fault, or any combination thereof
as defined in calibration. Recommend a power derate 1/2
to reduce the possibility of engine damage due to the
inability to sense temperature.
• Non-emissions related fault
The Engine Coolant Temperature sensor is a thermistor (tem-
perature sensitive resistor) located in the engine coolant.
Some engines use an ECT sensor that is located in the coolant
near the thermostat. Some engines use a CHT (Cylinder Head
Temperature) sensor that is located in the coolant in the cylin-
der head. If the engine is equipped with an ECT sensor then
the CHT value is estimated. If equipped with a CHT sensor then
the ECT value is estimated. The ECM provides a voltage divider
circuit so that when the coolant is cool, the signal reads higher
voltage, and lower when warm.
This fault will set if signal voltage is less than the limit defined
in the diagnostic calibration any time engine is running. The
limit is generally set to 0.10 VDC. The ECM will use a default
value for the CHT/ECT sensor in the event of this fault.