Grand Cherokee 2WD L6-4.0L VIN S (1997)
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Output shaft speed sensor
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Module timer
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Engine rpm
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MAP sensor
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Brake switch
Transmission Relay
TRANSMISSION RELAY-PCM OUTPUT
The output to this relay provides battery voltage to the Overdrive (OD), Torque Converter Clutch (TCC) and governor pressure solenoids. Once
battery voltage is applied to the solenoids, they are individually activated by the Powertrain Control Module (PCM) through OD, TCC and
governor pressure outputs. The relay is located in the Power Distribution Center (PDC). Refer to label on PDC cover for relay location.
Overview
POWERTRAIN CONTROL MODULE
The Powertrain Control Module (PCM) operates the fuel system, ignition system, charging system, transmission controls, speed control system, and
several instrument panel lights/gauges. 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 Outputs. The sensors and switches that provide
inputs to the PCM are considered Powertrain Control Module 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.
NOTE: 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
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Oil pressure
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Output shaft speed sensor
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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
