Okay guys to clear this up i,m taking all this info right out of the GM Light Duty Truck 10-30 Series Shop Manual...
COMPUTER COMMAND CONTROL SYSTEM
CALIFORNIA ONLY
The (SYSTEM) in California is an electronically emission system that controls:
Fuel delivery(E4ME electronic Qjet)
Air Injection Reactor(AIR)
Evaporative Emission Control(EEC)
Electronic Spark Timing(EST)
Torque Converter Clutch(TCC)
This system monitors various engine/vehicle operating conditions and using this information can control engine related systems thereby making constant adjustments to maintain good vehicle performance under all driving conditions while allowing the catalytic converter to effectively control exhaust emissions.
ELECTRONIC Control Module(ECM)
The ECM located in the passenger compartment, is the control center of the Computer Command Control System.
The ability of the ECM to recognize and adjust for vehicle variations(engine transmission,vehicle weight,axle ratio,etc) is provided by a removable Calibration Unit(PROM) that is programmed to tailor the ECM for the particular vehicle. There are specific ECM/PROM combinations for each specific vehicle and they are not interchangeable.
The ECM also performs the diagnostic function of the system, recognizing operational problems, alerting the driver through the "CHECK ENGINE" light and storing a code or codes which identify the problem areas to aid the technician in making repairs.
I have this system in my truck and it works, in my 22 years of ownership it hasn't failed a Smog check yet, granted it isn't built for performance but as my everyday driver she runs great but when that time comes, if ever, and she's past having to do smog tests you can bet a lot of this stuff will be gone
John
83 Silverado
KN
HYPERTECH
FLOWMASTER