Programming and Relearning

Flash Electrically Eraseable Programmable Read Only Memory-Flash EEPROM

Flash Electrically Eraseable Programmable Read Only Memory is contained in an Integrated Circuit (IC) internal to the PCM. The EEPROM contains the vehicle strategy including calibration information specific to the vehicle. The IC has the capability to be reprogrammed or reflashed. This is described below by the Flash EEPROM Procedure.

As part of the calibration there is an area referred to as the Vehicle Identification (VID) Block. The VID block must be programmed when replacing the PCM and is described under Programming the VID Block for a Replacement PCM. The VID block is an existing PCM can also be tailored to accommodate various hardware changes made to the vehicle since production. This is described under Making Changes to the VID Block and also under the FLASH EEPROM Procedure. The VID block contains many items used by the strategy for a variety of functions. Some of these items include the VID number, octane adjust, fuel octane. fuel type, vehicle speed limit, tire size, axle ratio, the presence of speed control, four wheel drive and manual versus non manual shift on the fly. Only items applicable to vehicle hardware and supported by the VID block will be displayed on the scan tool.

When changing items in the VID block, the strategy will place range limits on certain items such as tire and axle ratio. The VID block is also limited to the number of times to be reconfigured. When this limit is reached, the scan tool will display a message indicating the need to reflash the PCM to reset the VID block. This is accomplished by the Flash EEPROM Procedure.


Programming the VID Block for a Replacement PCM

A new PCM will contain the latest strategy and calibration level for a particular vehicle. However, the VID block will be blank and in need of programming. There are two procedures available. The first is an automatic data transfer from the old PCM to the new PCM and the second is manual data entry into the new PCM.

Automatic data transfer will be performed if the old PCM is capable of communicating. This is done by the use of the scan tool to retrieve data from the old PCM before removing from the vehicle. The stored data can now be downloaded to the new PCM after replacing. This same process can also be accomplished during the Flash EEPROM Procedure described below.

Manual data entry must be performed if the old module is damaged and not capable of communicating. Remove and replace the old PCM. Contact the "AS BUILT" data center by fax for the data needed to manually update the VID block with the scan tool. Contact the center ONLY if the old PCM cannot be used. The following information will need to be faxed in: dealer name, dealer P & A code, dealer phone number, dealer fax number, technician's name, VIN and module being programmed. The necessary VID block data will then be faxed back. Enter the vehicle data string provided by the "AS BUILT" data center. Refer to the Worldwide Diagnostic System users manual for details.