General System

Computerized Engine Control System:

The computerized engine control system is the central control for electronic gasoline injection (EGI), electronic spark advance (ESA), and idle speed control (ISC). The control system does this by monitoring vehicle operating conditions like brake light switch position, vehicle speed, electrical load, power steering pressure, air conditioning operation, exhaust oxygen content (oxygen sensor), coolant temperature, barometric pressure, intake air temperature, throttle position, intake air volume, and engine speed.
The computer system has a built-in diagnostic system that detects system malfunctions. This system will alert the driver if a malfunction occurs by illuminating the Malfunction Indicator (CHECK) Light. The light can also be used to extract trouble codes from the computer system.
In addition to displaying computer system malfunction codes (codes only on California models), the Malfunction Indicator (CHECK) Light on Federal trucks acts as an emission maintenance warning. The Malfunction Indicator (CHECK) Light will come on at 60,000 miles for EGR and at 80,000 miles for Oxygen sensor.