General System Description

DESCRIPTION
The Control Module refers to the VCM. The control module is designed to maintain exhaust emission levels to Federal or California standards while providing excellent driveability and fuel efficiency. Review the components and wiring diagrams in order to determine which systems are controlled by each specific control module. The control module monitors numerous engine and vehicle functions. The control module controls the following operations:

^ Fuel control
^ Ignition Control (IC).
^ Knock Sensor (KS) system.
^ Automatic transmission shift functions.
^ Cruise Control Enable.
^ Generator.
^ Evaporative Emission ([1][2]EVAP) Purge.
^ A/C Clutch Control
^ Cooling Fan Control

OPERATION
The Control Module supplies a buffered voltage to various sensors and switches. The input and output devices in the control module include an analog to digital converters, signal buffers, counters, and special drivers. The Control Module controls most components with electronic switches which complete a ground circuit when turned ON. These switches are arranged in groups of 4 and 7 called one of the following:

^ Quad Driver Module
^ Output Driver Modules

The surface mounted Quad Driver Module can independently control up to 4 outputs (Control Module) terminals. The Output Driver Modules can independently control up to 7 outputs. Not all outputs are always used.

ENGINE CONTROLS INFORMATION
The driveability and emissions information describes the function and operation of the control module, The emphasis is placed on the diagnosis and repair of problems related to the system.

Engine Components, Wiring Diagrams, and Diagnostic Tables (DTCs):

^ Component Locations.
^ Wiring Diagrams.
^ Control Module Terminal End View and Terminal Definitions.
^ On-board Diagnostic (OBD) System Check.
^ Diagnostic Trouble Code Tables (DTCs).

The Component System includes the following items:

^ Component and circuit description.
^ On-vehicle service for each sub-system.
^ Functional checks and Diagnostic Tables.
^ How To Use Electrical Systems Diagnostic Information.

The DTCs also contain diagnostic support information containing circuit diagrams, circuit or system information, and helpful diagnostic information.

Control Module Service Precautions

The control module is designed to withstand normal current draws associated with vehicle operations.

Avoid overloading any circuit. When testing for opens or shorts, do not ground any of the control module circuits unless instructed. When testing for opens or shorts, do not apply voltage to any of the control module circuits unless instructed. Only test these circuits with a digital voltmeter J 39200, while the control module connectors remain connected to the control module.