Computers and Control Systems: Description and Operation

The computerized engine control system is used to control fuel, ignition, emission control system and other components. The system monitors engine and vehicle operating conditions and adjust the engine and vehicle control systems to provide maximum operating efficiency, resulting in reduced exhaust emissions.
The systems are controlled by the Powertrain Control Module (PCM) which:

Detects the following:
1. A/C operation - Air conditioning switch.
2. Air/Fuel Ratio (Oxygen Concentration) - Heated oxygen sensor.
3. Barometric Pressure - EGR boost sensor.
4. Braking Signal - Brake switch.
5. Cranking Signal - Ignition switch (START position).
6. E/L Operation - Cooling fan relay - Fan switch.
7. Engine Coolant Temperature - Engine coolant temperature sensor.
8. Engine Speed - Camshaft position sensor.
9. In-Gear Condition - Neutral and clutch switches (MTX) - Transmission range switch (ATX).
10. Intake Air Amount - Mass air flow sensor.
11. Intake Air Temperature - Intake air temperature sensor.
12. No.1 Piston TDC - Camshaft position sensor.
13. P/S Operation - Power steering pressure switch.
14. Initial Set Signal - Data link connector.
15. Throttle Valve Opening Angle - Throttle position sensor.
16. OBDII System Function - EGR boost sensor - Crankshaft position sensor.

Controls the Operation of:
1. A/C (Cut-off) - A/C relay.
2. Fail-Safe Function - MIL.
3. Fuel Injection System - Fuel injector.
4. Idle Speed Control - IAC valve.
5. Ignition Timing Control System - Ignition control module.
6. On-Board Diagnostic System.
7. Purge Control System - Purge solenoid valve.
8. Lockup Control System - Transmission Controls (ATX).