Dtc 117- Ect/Cht Low Voltage - JLG 1200SJP Service Maintenance Manual

SECTION 3 - CHASSIS & TURNTABLE

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.
3-140
T A N /W H IT E
BLA C K /G R E E N
This fault will set if the signal voltage is less than the limit
defined in the diagnostic calibration anytime the 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.
– JLG Lift – 3121142