System Description

Computerized Engine Controls:

The engine systems of this vehicle are controlled by a digital, pre-programmed, computer referred to as the "engine controller", (formerly known as the Single Board Engine Controller or SBEC), which has the ability to update and revise its programming to meet changing operating conditions. The engine controller provides precise control of, air/fuel mixture, ignition timing, emission control devices, cooling fan, charging system, and idle speed.

The engine controller uses the input from various sensors and switches to determine engine operating conditions. After determining operating conditions the engine controller actuates various output devices to optimize [1] engine performance. Input and output devices are listed below.

The engine controller monitors many of its input and output circuits for faults. If a fault is detected in any monitored system, this information is stored in memory as a fault code and the CHECK ENGINE lamp in the instrument panel is illuminated. Fault code information can be read using the CHECK ENGINE lamp or a scan tool. If the CHECK ENGINE lamp is illuminated and/or there is a fault code other than code 55 set in memory this problem should be corrected before proceeding with other diagnosis.

[1] Optimum performance: best compromise between power, fuel consumption, and emissions.

INPUTS

Air Conditioning Switch/Air Conditioning Low Pressure Switch
Battery Voltage
Brake Switch
Coolant Temperature Sensor
Engine Speed (Distributor Pick-up)
Heated Oxygen Sensor
Manifold Absolute Pressure (MAP) Sensor
Throttle Body Temperature Sensor
Throttle Position Sensor (TPS)
Vehicle Distance (Speed) Sensor

OUTPUTS

Air Conditioner Clutch Relay
Alternator Field
Automatic Idle Speed (AIS) Motor
Automatic Shutdown (ASD) Relay
Canister Purge Solenoid
Check Engine Lamp (CEL)
EGR Control Solenoid Valve
Emission Maintenance Reminder (EMR) Lamp
Fuel Injector Pulse Width
Ignition Coil
Radiator Fan Relay
Self-Diagnosis Output