JLG 460SJ Service Manual - Manual (Page 122)

SECTION 3 - CHASSIS & TURNTABLE
3-70 – JLG Lift – 3120895
ENGINE COOLANT TEMPERATURE (ECT)
SENSOR
The engine coolant temperature (ECT) sensor is a g
thermistor (a resistor which changes value based on tem-
perature) mounted in the engine coolant stream. Low cool-
ant temperature produces a high resistance of 100,000
ohms at -40°C (-40°F). High temperature causes a low
resistance of 70 ohms at 130°C (266°F). The ECM sup-
plies a 5-volt signal to the ECT sensor through resistors in
the ECM and measures the voltage. The signal voltage will
be high when the engine is cold and low when the engine
is hot. By measuring the voltage, the ECM calculates the
engine coolant temperature. Engine coolant temperature
affects most of the systems that the ECM controls.
After engine start-up, the temperature should rise steadily
to about 85°C (185°F). it then stabilizes when the thermo-
stat opens. If the engine has not been run for several
hours (overnight), the engine coolant temperature and
intake air temperature displays should be close to each
Table 3-9. ECM Diagnostic Trouble Codes
Diagnostic
Trouble
Code
Description
11 All Systems OK
12 Throttle Position (TP) Sensor Low Voltage
14 Manifold Absolute Pressure (MAP) Low Voltage
21 Overspeed
22 Throttle Position (TP) Sensor High Voltage
24 Manifold Absolute Pressure (MAP) High Voltage
31 Fuel Pump Low Voltage
32 Heated Oxygen Sensor (HO2S) Low Voltage
33 Engine Coolant Temperature (ECT) Sensor High Voltage
35 Intake Air Temperature (IAT) Sensor High Voltage
41 Fuel Pump High Voltage
42 Heated Oxygen Sensor (HO2S) High Voltage
43 Engine Coolant Temperature (ECT) Sensor Low Voltage
45 Intake Air Temperature (IAT) Sensor Low Voltage
51 Low Oil Pressure
52 Crankshaft Position (CKP) Sensor Extra/Missing Pulses
53 Camshaft Position Sensor (CMP) Sensor Illegal Pattern
54 Engine Control Module (ECM) Fault Illegal Operation
55 Engine Control Module (ECM) Fault Illegal Interruption
56 Engine Control Module (ECM) Fault COP (Computer Operating Properly) Failure
61 System Voltage Low
62 System Voltage High