General System Description

The electronic control systems are controlled by a Power Train Control Module (PCM), formerly called a Single Board Engine Controller II (SBEC II). This controller controls the intake heater relays, speed control, and overdrive solenoid. 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. The PCM tests many of its own input and output circuits. If a Diagnostic Trouble Code (DTC) is found in any major system, this information is stored in the controllers memory. If a trouble code exists, the code information can be displayed to a technician through a suitable diagnostic scan tool.


PCM INPUTS

- Air Conditioning Control Switch
- Auto Shutdown (ASD) Sense circuit
- Battery Voltage
- Brake Light Switch
- Charge Air Temperature Sensor
- Coolant Temperature Sensor (Auto Trans only)
- Engine Speed Sensor
- Ignition Sense
- Neutral Safety Switch (Auto trans only)
- Overdrive/Override Switch
- Power Ground
- Sensor Return
- Serial Communications Interface (SCI) (Scan tool connection)
- Signal Ground
- Speed Control Switch
- Transmission Thermo-Switch (Auto trans only)
- Throttle Position Sensor (TPS) (Auto trans only)
- Vehicle Speed Sensor
- Water-In-Fuel Sensor



PCM OUTPUTS
- AC Clutch Relay
- Air Intake Heater Relays
- Generator Field Control
- Auto Shut-down Relay (ASD)
- Malfunction Indicator Lamp
- Overdrive Indicator Lamp
- Overdrive Solenoid
- Serial Communication Interface (SCI) Transmit
- Speed Control
- Tachometer
- Wait-To-Start Indicator Lamp
- Water-In-Fuel Indicator Lamp