With Vehicle Control Module (VCM-A)

Vehicle Control Module (VCM-A):

DESCRIPTION
The Vehicle Control Module (VCM-A) is located on the right hand side fenderwell, is the control center for the fuel emissions automatic transmission control functions and antilock brake systems. The VCM-A constantly monitors the information from various sensors and controls the component systems which affect engine, transmission and antilock brake operation. The VCM-A also performs the diagnostic function of the system. The VCM-A can alert the driver through the Malfunction Indicator Lamp (MIL) "Service Engine Soon" or antilock indicator lamp and store one or more Diagnostic Trouble Codes (DTCs) which can identify the problem areas to aid the technician in making repairs. Refer to System Diagnosis for further information on using the diagnostic function of the VCM-A, for engine operation. Refer to Transmission and Drivetrain for diagnosis of automatic transmission. Refer to Brakes and Traction Control/Brakes/Antilock Brake System for further information on antilock brakes.

The VCM-A in this vehicle is programmable. The only services allowed on the VCM-A is control module replacement with (KS calibrator) PROM transferred or (KS calibrator) PROM only. The (KS calibrator) PROM contains the integrated knock sensor calibration. The calibrations are stored in the VCM-A in the Electronically Erasable Programmable Read Only Memory (EEPROM).

When replacing the VCM-A, it will be mandatory to program the EEPROM and transfer the (KS calibrator) PROM to the new VCM-A. Refer to Service and Repair VCM-A Replacement.

The four calibrations required for the VCM-A are Powertrain, ABS, VSS buffer and A/C. Each calibration will have its own part number. Determination of the correct calibrations for a particular vehicle will be based on the VIN number of the vehicle.

OPERATION
The VCM-A is designed to process the various input information and then sends the necessary electrical responses to control fuel delivery, spark timing, and other emission control systems. The input information has an interrelation to more than one output, therefore, if the one input failed it can affect more than one systems operation.