RAM 3500 Truck 4WD L6-5.9L DSL Turbo VIN C (2002)
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Signal ground
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Speed control resume switch
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Speed control set switch
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Speed control ON/OFF switch
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Transmission governor pressure sensor
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Transmission temperature sensor
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Vehicle speed inputs from ABS or RWAL system
PCM Outputs
After inputs are received by the PCM, certain sensors, switches and components are controlled or regulated by the PCM. These are considered PCM
Outputs. These outputs are for:
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A/C clutch relay and A/C clutch Auto shutdown (ASD) relay
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CCD bus (+/-) 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 scan tool
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5 volt sensor supply
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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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Malfunction indicator lamp (Check engine lamp)
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Overdrive warning lamp (if equipped)
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Speed control vacuum solenoid
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Speed control vent solenoid
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Tachometer (if equipped)
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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 (governor solenoid)
Modes of Operation
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 (O2S)
sensors is not monitored during Open Loop modes.
During Closed Loop modes, the PCM will monitor the oxygen (O2S) 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-1 part fuel. By monitoring the exhaust oxygen content through the
O2S 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
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Acceleration
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Deceleration
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Wide open throttle (WOT)
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Ignition switch OFF
The Ignition Switch ON, Engine Start-Up (crank), Engine Warm-Up, Acceleration, Deceleration and Wide Open Throttle modes are Open Loop modes.
The Idle and Cruise Modes, (with the engine at operating temperature) are Closed Loop modes.
Ignition Switch (Key-ON) Mode
This is an Open Loop mode. When the fuel system is activated by the ignition switch, the following actions occur:
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The PCM pre-positions the idle air control (IAC) motor.
