General System Description

System Components 8.0 Truck:

PCM SYSTEM
This vehicle uses a Powertrain Control Module (PCM) to control the sequential multi-port fuel injection.

The engine systems in this vehicle are controlled by the PCM. These components provide precise air/fuel mixture control for all driving conditions, and regulates ignition timing, emission control devices, cooling fan, charging system, and idle speed. The PCM is a digital pre-programmed computer that has the ability to update and revise its programming to meet changing operating conditions.

Various sensors provide necessary input for the PCM to function correctly (See list of PCM inputs and outputs below). In addition to these sensors, various switches and relays are used to carry out commands or outputs from the PCM.

The PCM tests many of its own input and output circuits. If a fault is found in any major system, this information is either stored in memory or displayed as a light on the instrument panel. If a fault exists, the fault information can be displayed to a technician through the instrument panel Malfunction Indicator Lamp or a suitable diagnostic scan tool.


PCM INPUTS
- A/C Request - A/C Select
- Automatic Shut Down (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.