Powertrain Management: Description and Operation

Powertrain Control Module (PCM):

CONTROL MODULE FUNCTION
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.

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.

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.

MAINTENANCE SCHEDULE
For Maintenance Information refer to Maintenance.

SYSTEM STATUS AND DRIVE CYCLE FOR INSPECTION/MAINTENANCE

IMPORTANT:
The System Status display indicates only whether or not the test has been completed. The System Status display does not necessarily mean that the test has passed. If a Failed Last Test indication is present for a DTC associated with one of the above systems, that test is failed; diagnosis and repair is necessary in order to meet the I/M 240 requirement. Verify that the vehicle passes all of the diagnostic tests associated with the displayed System Status prior to returning the vehicle to the customer.

Following a DTC info clear, a battery disconnect or a Control Module replacement, all System Status information will clear.

The System Status selection is included in the scan tool System Info menu.

Several states require that the I/M 240 (OBD II system) pass on-board tests for the major diagnostics prior to having a vehicle emission inspection. This is also a requirement to renew license plates in some areas.

Using a scan tool, the technician can observe the System Status (complete or not complete) in order to verify that the vehicle meets the criteria to comply with local area requirements. Using the System Status display, any of the following systems or combination of systems may be monitored for I/M Readiness:

^ The three-way catalytic converter.

^ The Heated Oxygen Sensors (HO2S).

^ The HO2S heaters.

^ The EGR system.

^ The Fuel Trim System.