Hello.

Do I have a PCM or VCM in my car?
I hava a 95 Blazer 4x4, 4,3l W, auto tans.
I`ve posted a picture of that I think is the control module.
The box have 4 big plug and a small one.

 

ECM: Engine Control Module
PCM: Powertrain Control Module
VCM: Vehicle Control Module
TCM: Transmission Control Module
ICM: Ignition Control Module
BCM: Body Control Module

Vehicle Control Module

General Description

The VCM is located on the right hand side fenderwell. The VCM is the control center for the fuel emissions automatic transmission control functions and the antilock brakes systems.
The VCM constantly monitors the information from the various sensors. The VCM controls the component systems which affect the engine, the transmission, and the antilock operation.
The VCM alerts the driver through the Malfunction Indicator Lamp (MIL) or the antilock indicator lamp. The VCM stores the DTCs which identify the problem areas for the technician making repairs. Refer to Vehicle Control Module (Serial Data Communication) , for further information on using the diagnostic function of the VCM for engine operation.
Refer to Transmission for the diagnosis of the automatic transmission. Refer to Section 5E3B in the appropriate service manual for further information on the antilock brakes.
The VCM in this vehicle is programmable. The only services allowed on the VCM is the control module replacement with the KS calibrator PROM transferred or the KS calibrator PROM only.
The KS calibrator contains the up integrated knock sensor calibration. The VCM stores the 4 calibrations in the Electronically Erasable Programmable Read Only Memory (EEPROM).
When replacing the VCM, programming the EEPROM and transferring the KS calibrator PROM to the new VCM is mandatory. Refer to the EEPROM Programming .
The 4 calibrations required for the VCM are the Powertrain, the ABS, the VSS buffer, and the A/C. Each calibration has its own part number. Determine the correct calibrations for a particular vehicle based on the VIN number of the vehicle.
Vehicle Control Module (VCM)

The VCM processes the various input information. The VCM sends the necessary electrical responses to the control fuel delivery, the spark timing, and the other emission control systems. The input information interrelates to more than one output; therefore, if the one input fails, the failure can affect more than one system.

 

Tanks for the answer.

The box on the picture i uploaded is placed on the right side of the engine, so that must be the VCM. What is the different from a car with PCM and VCM?

 

What your looking at is what they call your power control module basicly your main computer. Your OBD trouble and most diagnostic codes come from and are stored in that. Heres a good explaination.
Powertrain Control Module (PCM) Yours by the way should be what they refer to around here as an obd1.5