Cherokee 4WD LHD L6-4.0L VIN S (2001)
information.
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When engine has reached operating temperature, the PCM will begin monitoring O(2)S sensor input. The system will then leave the warm-up
mode and go into closed loop operation.
Idle Mode
When the engine is at operating temperature, this is a Closed Loop mode. At idle speed, the PCM receives inputs from:
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Air conditioning select signal (if equipped)
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Air conditioning request signal (if equipped)
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Battery voltage
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Crankshaft position sensor
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Engine coolant temperature sensor
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Extended idle switch (4.0L engine with police package only)
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Intake manifold air temperature sensor
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Manifold absolute pressure (MAP) sensor
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Throttle position sensor (TPS)
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Camshaft position sensor signal (in the distributor)
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Battery voltage
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Park/neutral switch (gear indicator signal-auto. trans. only)
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Oxygen sensors
Based on these inputs, the following occurs:
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Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control injection sequence and injector pulse
width by turning the ground circuit to each individual injector ON and OFF.
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The PCM monitors the O2S sensor input and adjusts air-fuel ratio by varying injector pulse width. It also adjusts engine idle speed through the
idle air control (IAC) motor.
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The PCM adjusts ignition timing by increasing and decreasing spark advance.
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The PCM operates the A/C compressor clutch through the A/C compressor clutch relay. This is done if A/C has been selected by the vehicle
operator and specified pressures are met at the high and low-pressure A/C switches. Refer to Heating and Air Conditioning for additional
information.
The optional Extended Idle Switch is used to raise and hold the engine idle speed to approximately 1000 rpm. This is when the shifter is in either
the Park or Neutral position and throttle pedal is not used. A rocker-type switch (extended idle switch) is mounted to the instrument panel. This
switch will supply a ground circuit (input) to the PCM. The switch is available only with 4.0L engine when supplied with optional police package.
Cruise Mode
When the engine is at operating temperature, this is a Closed Loop mode. At cruising speed, the PCM receives inputs from:
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Air conditioning select signal (if equipped)
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Air conditioning request signal (if equipped) Battery voltage
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Engine coolant temperature sensor
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Crankshaft position sensor
Intake manifold air temperature sensor Manifold absolute pressure (MAP) sensor
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Throttle position sensor (TPS)
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Camshaft position sensor signal (in the distributor)
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Park/neutral switch (gear indicator signal-auto. trans. only)
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Oxygen (O2S) sensors
Based on these inputs, the following occurs:
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Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then adjust the injector pulse width by turning the
ground circuit to each individual injector on and off
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The PCM monitors the O(2)S sensor input and adjusts air-fuel ratio. It also adjusts engine idle speed through the idle air control (IAC) motor.
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The PCM adjusts ignition timing by turning the ground path to the coil on and off.
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The PCM operates the A/C compressor clutch through the clutch relay. This happens if A/C has been selected by the vehicle operator and
requested by the A/C thermostat.
Acceleration Mode
This is an Open Loop mode. The PCM recognizes an abrupt increase in throttle position or MAP pressure as a demand for increased engine output
and vehicle acceleration. The PCM increases injector pulse width in response to increased throttle opening.
Deceleration Mode
When the engine is at operating temperature, this is an Open Loop mode. During hard deceleration, the PCM receives the following inputs.
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Air conditioning select signal (if equipped)
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Air conditioning request signal (if equipped)
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Battery voltage
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Engine coolant temperature sensor
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Crankshaft position sensor
