ELECTRONIC FUEL INJECTION
5-113
Coolant passes through the cylinder and by the sensor probe,
varying a resistance reading, which is relayed to the ECU. This
signal is processed by the ECU and compared to its
programming for determining the fuel and ignition
requirements during operation. The ECU also uses this signal
to determine when to activate the fan during operation. If for
any reason the engine temperature sensor circuit is interrupted,
the fan will default to “ON”.
ECT SENSOR TEST
To quickly rule out other components and wiring related to the
ETS, disconnect the harness from the ETS. The fan should turn
on and ‘HOT’ should indicate on the instrument cluster. This
indicates all other components are working properly.
ECT Resistance Specification:
10000±
±±
±439Ω(25℃
℃℃
℃ / 77℉
℉℉
℉)
ECT SENSOR REPLACEMENT
1. Drain coolant to level below sensor.
2. Disconnect sensor from engine harness.
3. Using a wrench, remove and replace the sensor, applying a
light coating of thread sealant to aid installation.
4. Torque the sensor to 20 Nm (15 ft. lbs.).
ECT Retaining Bolt Torque:
20 Nm (15 ft. lbs.)
IGNITION OPERATION OVERVIEW
The ignition coil is used to provide high voltage to fire the
spark
plugs. When the ignition key is on, DC voltage is present
in primary side of the ignition coil windings. During engine
rotation, an AC pulse is created within the crankshaft position
sensor for each passing tooth on the flywheel. The two-tooth
gap creates an “interrupt” input signal, corresponding to
specific crankshaft position for PTO cylinder. This signal
serves as a reference for the control of ignition timing. The
ECU then calculates the time interval between the consecutive
pulses, and determines when to trigger the voltage spike that
induces the voltage from the primary to the secondary coil
windings to fire the spark plugs.
GENERAL TROUBLESHOOTING
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General