Isuzu N 2008 Series Workshop Manual page 363

1A-360 Engine Control System (4JJ1)
The CMP sensor is installed on the timing chain
sprocket cover at the front of the camshaft idle gear.
The CMP sensor detects total of five projections per
one engine cycle (four projections arranged equally
every 90° and one reference projection on the timing
chain sprocket surface). The CMP sensor is a magnetic
resistance element
generates a square wave signal pulse.
Crankshaft Position (CKP) Sensor
Legend
1. Crankshaft position (CKP) sensor
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2
Legend
1. Crankshaft position (CKP) sensor
2. Sensor rotor
3. Rotating direction
(MRE) type sensor,
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The CKP sensor is located on the left-hand of the
cylinder block rear. The sensor rotor is fixed on the
crankshaft. There are 56 notches spaced 6° apart and
a 30° section that is open span. This open span portion
allows for the detection of top dead center (TDC). The
CKP sensor is a magnetic resistance element (MRE)
which type sensor, which generates a square wave signal
pulse. Detecting the open span portion from the CKP
sensor and one reference projection from the camshaft
position (CMP) sensor, the ECM determines cylinder
#1 compression TDC to ensure they correlate with
each other.
Engine Coolant Temperature (ECT) Sensor
Legend
1. Engine coolant temperature (ECT) sensor
The ECT sensor is installed to the thermostat housing.
The ECT sensor is a variable resistor and it measures
the temperature of the engine coolant. When the ECT
sensor is cold, the sensor resistance is high. When the
engine coolant temperature increases, the sensor
resistance decreases. With high sensor resistance, the
ECM detects a high voltage on the signal circuit. With
lower sensor resistance, the ECM detects a lower
voltage on the signal circuit.
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