Powertrain Control Module
The Powertrain Control Module (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 PCM Outputs. The sensors and switches that provide inputs to the PCM are considered 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. The PCM is located under the passenger side front fender. See Fig 1 .
The following inputs may be used by the PCM.
- A/C Request (If Equipped With Factory A/C)
- A/C Select (If Equipped With Factory A/C)
- Auto Shutdown (ASD) Sense
- Battery Temperature
- Battery Voltage
- Brake Switch
- PCI Bus Circuits
- Camshaft Position Sensor Signal
- Crankshaft Position Sensor
- Data Link Connection For DRBIII(R) Scan Tool
- Engine Coolant Temperature Sensor
- Fuel Level
- Generator (Battery Voltage) Output
- Ignition Circuit Sense (Ignition Switch In On/Off/Crank/Run Position)
- Intake Manifold Air Temperature Sensor
- Leak Detection Pump (Switch) Sense (If Equipped)
- Manifold Absolute Pressure (MAP) Sensor
- Oil Pressure
- Output Shaft Speed Sensor
- Overdrive/Override Switch
- Oxygen Sensors
- Park/Neutral Switch
- Power Ground
- Sensor Return
- Signal Ground
- Speed Control Multiplexed Single Wire Input
- Throttle Position Sensor
- Transmission Governor Pressure Sensor
- Transmission Temperature Sensor
- Vehicle Speed Inputs From ABS Or RWAL System
The following outputs may be used by the PCM.
- A/C Clutch Relay
- Auto Shutdown (ASD) Relay
- PCI Bus Circuits For Speedometer, Voltmeter, Fuel Gauge, Oil Pressure Gauge/Lamp, Engine Temp. Gauge & Speed Control Warning Lamp
- Data Link Connection For DRBIII(R) Scan Tool
- EGR Valve Control Solenoid (If Equipped)
- EVAP Canister Purge Solenoid
- Five-Volt Sensor Supply (Primary)
- Five-Volt Sensor Supply (Secondary)
- Fuel Injectors
- Fuel Pump Relay
- Generator Field Driver (-)
- Generator Field Driver (+)
- Generator Lamp (If Equipped)
- Idle Air Control (IAC) Motor
- Ignition Coil
- Leak Detection Pump (If Equipped)
- Malfunction Indicator Lamp (Check Engine Light), Driven Through PCI Circuits
- Overdrive Indicator Lamp (If Equipped)
- Speed Control Vacuum Solenoid
- Speed Control Vent Solenoid
- Tachometer (If Equipped), Driven Through PCI Circuits
- Transmission Convertor Clutch Circuit
- Transmission 3-4 Shift Solenoid
- Transmission Relay
- Transmission Temperature Lamp (If Equipped)
- Transmission Variable Force Solenoid