Flash Electrically Erasable Programmable Read Only Memory (EEPROM): Description

Flash EEPROM is contained in an integrated circuit internal to the PCM. The flash EEPROM contains the vehicle strategy, including calibration information specific to the vehicle, and is capable of being reprogrammed or reflashed repeatedly.

As part of the calibration there is an area referred to as the vehicle identification (VID) block in the PCM. The VID block must be programmed when installing a new PCM as described under Programming the VID Block for a New PCM. Not carrying out this procedure may generate DTCs P1635 Tire Axle Out of Acceptable Range or P1639 Vehicle ID Block Corrupted, Not Programmed. The VID block in an existing PCM can also be tailored to accommodate various hardware or parameter changes made to the vehicle since production. This is described under Making Changes to the VID Block, and also under Making Changes to the PCM Calibration. The VID block contains many items used by the strategy for a variety of functions. Some of these items include the vehicle identification number (VIN), octane adjust, fuel octane, fuel type, vehicle speed limit, tire size, axle ratio, the presence of speed control, and four wheel drive electronic shift on the fly (ESOF) versus manual shift on the fly (MSOF). Only items applicable to the vehicle hardware and supported by the VID block are displayed on the scan tool.

When changing items in the VID block, the strategy places range limits on certain items such as tire and axle ratio.

Each of the procedures described below use the scan tool. Reprogramming can be carried out by a local Ford dealer or any non-Ford facility. There are other enhanced scan tools that may have reprogramming capabilities available. Refer to the scan tool manufacturers manual for instructions.