General System Description

System Components Typical:

PCM SYSTEM
The computerized engine control system is built around a Powertrain Control Module (PCM). The PCM monitors up to 22 inputs and responds with appropriate outputs to manage fuel delivery, ignition timing, and emission control devices, charging system, speed control and idle speed. The PCM is a pre-programmed, dual microprocessor digital computer. As operating conditions change.

The PCM adjusts injector pulse width and ignition timing for optimum performance and fuel economy.

The PCM controls fuel delivery. Fuel is injected into the intake manifold before the intake valve in precise amounts through electrically operated injectors. The injectors are fired in a specific sequence by the PCM. The PCM constantly adjusts the amount of fuel injected to meet changing operating conditions by controlling injector pulse width (the length of time the injector is energized).

The PCM also adjusts the ignition timing by controlling the ignition coil dwell.


PCM INPUTS
- A/C Request - A/C Select
- ASD Sense - Battery Voltage
- Brake Switch - Camshaft Position Sensor
- Crankshaft Position Sensor - Data Link Receive
- Engine Coolant Temp Sensor - Generator Output
- Ignition Circuit Sense - Intake Air Temp Sensor
- MAP Sensor - Overdrive/Override Switch
- Oxygen Sensor - Park/Neutral Switch
- Power Ground - Sensor Return
- Signal Ground - Speed Control Resume Switch
- Speed Control Set Switch - Speed Control Set Switch
- Throttle Position Sensor - Vehicle Speed Sensor


PCM OUTPUTS
- A/C clutch - Generator Field
- ASD Relay - Data Link Transmit
- Electronic EGR Transducer - EVAP Purge Solenoid
- Fuel Injectors - Fuel Pump Relay
- Ignition Coil - Idle Air Control Motor
- Malfunction Indicator Lamp - Shift Indicator Lamp
- Speed Control Solenoids - Tachometer

NOTE: Not all models use all inputs and outputs.