Grand Cherokee 2WD Limited V8-4.7L (2002)
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Ignition circuit sense (ignition switch in ON/OFF/crank/run position)
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Intake manifold air temperature sensor
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Leak detection pump (switch) sense (if equipped)
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Manifold Absolute Pressure (MAP) sensor
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Oil pressure
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Overdrive/override switch
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Oxygen sensors
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Park/neutral switch (auto. trans. only)
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Power ground
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Sensor return
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Signal ground
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Speed control multiplexed single wire input
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Throttle position sensor
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Transmission governor pressure sensor
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Transmission temperature sensor
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Vehicle speed (from ABS module)
NOTE: PCM Outputs:
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A/C clutch relay
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Auto shutdown (ASD) relay
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J1850 (+A) circuits for: speedometer, voltmeter, fuel gauge, oil pressure gauge/lamp, engine temp. gauge and speed control warn. lamp
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Data link connection for DRB III scan tool
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EGR valve control solenoid (if equipped)
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EVAP canister purge solenoid
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Fuel injectors
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Fuel pump relay
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Generator field driver (-)
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Generator field driver (+)
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Generator lamp (if equipped)
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Idle Air Control (IAC) motor
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Ignition coil
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Leak detection pump
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Malfunction indicator lamp (Check engine lamp). Driven through J1850 circuits.
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Overdrive indicator lamp (if equipped). Driven through J1850 circuits.
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Oxygen sensor heater relays (if equipped).
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Radiator cooling fan relay (pulse width modulated)
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Speed control source
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Speed control vacuum solenoid
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Speed control vent solenoid
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Tachometer (if equipped). Driven through J1850 circuits.
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Transmission convertor clutch circuit
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Transmission 3-4 shift solenoid
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Transmission relay
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Transmission temperature lamp (if equipped)
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Transmission variable force solenoid
MODES OF OPERATION
As input signals to the Powertrain Control Module (PCM) change, the PCM adjusts its response to the output devices. For example, the PCM must
calculate different injector pulse width and ignition timing for idle than it does for Wide Open Throttle (WOT).
The PCM will operate in two different modes: Open Loop and Closed Loop.
During Open Loop modes, the PCM receives input signals and responds only according to preset PCM programming. Input from the oxygen
(O(2)S) sensors is not monitored during Open Loop modes.
During Closed Loop modes, the PCM will monitor the oxygen (O(2)S) sensors input. This input indicates to the PCM whether or not the
calculated injector pulse width results in the ideal air-fuel ratio. This ratio is 14.7 parts air-to-i part fuel. By monitoring the exhaust oxygen content
through the O(2)S sensor, the PCM can fine tune the injector pulse width. This is done to achieve optimum fuel economy combined with low
emission engine performance.
The fuel injection system has the following modes of operation:
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Ignition switch ON
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Engine start-up (crank)
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Engine warm-up
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Idle
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Cruise
