RAM 2500 Truck 2WD V8-5.2L VIN Y (2000)
Powertrain Control Module: Description and Operation
PCM Operating Modes
Fig. 1 PCM Location
POWERTRAIN CONTROL MODULE (PCM)
The Powertrain Control Module (PCM) is located in the engine compartment. The PCM is referred to as JTEC (Jeep/Truck Engine Controller).
The PCM operates the fuel system. The PCM is a pre-programmed, triple microprocessor digital computer. It regulates ignition timing, air-fuel
ratio, emission control devices, charging system, certain transmission features, speed control, air conditioning compressor clutch engagement and
idle speed. The PCM can adapt its programming to meet changing operating conditions.
The PCM receives input signals from various switches and sensors. Based on these inputs, the PCM regulates various engine and vehicle
operations through different system components. These components are referred to as Powertrain Control Module (PCM) Outputs. The sensors
and switches that provide inputs to the PCM are considered Powertrain Control Module (PCM) Inputs.
The PCM adjusts ignition timing based upon inputs it receives from sensors that react to: engine rpm, manifold absolute pressure, engine coolant
temperature, throttle position, transmission gear selection (automatic transmission), vehicle speed and the brake switch.
The PCM adjusts idle speed based on inputs it receives from sensors that react to: throttle position, vehicle speed, transmission gear selection,
engine coolant temperature and from inputs it receives from the air conditioning clutch switch and brake switch.
Based on inputs that it receives, the PCM adjusts ignition coil dwell. The PCM also adjusts the generator charge rate through control of the
generator field and provides speed control operation.
PCM Inputs
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A/C request (if equipped with factory A/C)
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A/C select (if equipped with factory A/C)
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Auto shutdown (ASD) sense
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Battery temperature
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Battery voltage
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Brake switch
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CCD bus (+) circuits
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CCD bus (-) circuits
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Camshaft position sensor signal
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Crankshaft position sensor
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Data link connection for DRB scan tool
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Engine coolant temperature sensor
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Fuel level
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Generator (battery voltage) output
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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
